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SR4000 User Manual

1. luca l bes f ibusbSR 1 0 10 550 Setup a diii am apum el ic beri qn baso 1 010550SetUP tt ace ics icio m Choose Components M E S A Choose Install Location M E S A Choose which Features cf libusbSR 1 0 10 550 you wart to Choose the folder in which to instal libusb5R 1 0 10 550 install IMAGING IMAGING Check the components you want to install and uncheck the componerts you don t want to Setup will install libusbSR 1 0 10 550 in the Following folder To install in a different folder install Click Next to continuo dick Browse and select another Folder Click Install to start the installation Select the type of inszall Custom x d Or select the optional driver requirec speed P i C samples with d Geile you wish to E Y Interfaces ES pin E use E E Destination Folder v l fp Browse v matlab n Space required 1 0MB A El Space required 1 0MB m gt Space avaiable 3 8GB UNES TR Se ax I 1205058 1010350 Setup il al lt Sala qr its 1 010550 ep te d Installation Complete gt E Setup was completed successfully M ESA M E SA Completing the libusbSR 1 0 10 550 IMAGING Setup Wizard IMAGING Completed libusbSR 1 0 10 550 has been installed on your computer Click Finish to close this wizard Extract sr setreg m 100 c Extract sr settimeout m 100 Extract sr smplegu m 100 d Extract sr streamtcfile m 100 Extract sr unloadlib
2. 40 12 4 2 Setting a static IP address 1 40 12 4 3 Reverting to DHCP 2l sss 41 12 5 Silent Install in Windows 41 13 Software applications 42 o 42 A ee eve ae po Gee a a O A ee 43 13 1 2 Grayscale image 2 ll ss sss 44 13 1 3 Scaling of display color 2 2 ln 44 13 1 4 Important adjustments a 44 lr e ad id 44 errr 45 edie a Bia ee eo oe oe Soe E E T 46 13 22 Fiters ce ook ee Se ee ee ee eG a Ae a eS 47 13 2 3 Streaming lll ss s s soon 47 13 2 4 Further controls as e a s ae pan ls ses 47 13 3 Sample Code e 44 42 88 eee eee E a a A ee 48 MESA Imaging AG Technoparkstrasse 1 3 8005 Zurich MESA IMAGING 13 4 Matlab Interface 13 5 C Interface e so noa roy oa a ea 4 Help and Support 5 Electrical power and trigger connection b Ratings and conformance MESA Imaging AG Technoparkstrasse 1 8005 Zurich SR4000 User Manual M ESA SR4000 User Manual IMAGING 1 About this document This Manual allows you to operate with the SR4000 Time of Flight TOF camera in an efficient way In this document the following designations e SR4000 e Camera e Sensor will all be used and will always refer to the SR4000 TOF camera 1 1 Goal of this document This manual is designed to e instruct customers about basic functions of the SR4000 e help customers to use the SR4000 in an optimal way e and to address aspects of the safe elect
3. 11 2 Parameters affecting measurement quality The measures per pixel are distance in terms of the 14 bit phase shift angle amplitude x y z coordinate vectors and the confidence value The following parameters and operations modes can affect at least one of these MESA Imaging AG Technoparkstrasse 1 34 8005 Zurich M ESA SR4000 User Manual IMAGING 11 2 1 Integration Time The integration time is the length of time that the pixels are allowed to collect light see chapter 6 Four samples are taken to produce the phase measurement requiring four separate integration periods Therefore the total time required to capture a depth image is four times the Integration Time plus four times the readout time This is reflected in the achievable frame rate for a given integration time The integration time can be set with int SR_SetIntegrationTime SRCAM srCam unsigned char intTime where the second argument intTime is a value from 0 to 255 that sets the integration time T in ms according to the following formula IT 0 300 ms intTime 0 100 ms 11 1 The frame rate here denoted as FR depends on integration time 1 BSEC SERO 11 2 where RO 4 6 ms is the read out time By default the parameter intTime is set to 30 Ox1E in hexadecimal This leads to an integration time of T 3 3 ms and to an effective frame rate of FR 31 5 fps The fastest frame rate is limited by the transferration of the image to the
4. C Program FilesMMesalmagingNSwissrangerNSwissranger chm and can be easily opened by following Start Programs Mesalmaging SwissRanger SwissRanger API from the Windows start panel Linux user s can download the documentation from http www mesa imaging ch dlm php fname customer driver Swissranger HTML doci 0 12 x zip The functions that are provided can be divided into three main groups e Functions that are related to the interfacing with an application e Functions that have impact on the image contents and measurement accuracy e Filters and auxiliary function In this chapter the first three sections are addressing the three groups as described above The fourth section is devoted to some sample codes Here the C C functions are described However the same functionality is offered with the interfaces to Matlab and Python 11 1 Interfacing functions 11 1 1 Opening and closing The camera is an instantiated object of SRCAM and API functions take a variable of this type as argument In order to retrieve the camera s data it needs to be opened first i e the communication via Ethernet or USB has to be initialized The main opening functions are int SR OpenDIg SRCAM srCam int mode HWND parent int SR OpenUSB SRCAM srCam unsigned int serialNumber int SR OpenETH SRCAM srCam const char addr int SR OpenFile SRCAM srCam const char filename All these functions open a camera object and are to be followed by SR_Close
5. to close the camera object In the case of int SR OpenFile the camera object does not refer to a real camera but to a file stream that was recorded before This enables for offline development and testing The opening functions are described in the following paragraphs MESA Imaging AG Technoparkstrasse 1 31 8005 Zurich M ESA SR4000 User Manual IMAGING Opening with a dialog The function SR_OpenDlg opens a camera that can be selected by the user in the selection menu The following options are available and can be selected with the parameter mode 1 try to open previous camera if it failed error is returned no selection dialog opened 2 always open selection dialog 3 try to open previous camera if it failed open selection dialog In Windows the open dialog shows up as a selection window see figure 13 2 on page 43 Ethernet and USB cameras are listed in this window The Ethernet cameras must be in the same network as the host PC You have to select a camera or a camera file stream as described below from the list with a left mouse click followed by a click on the Connect button The opening dialog can be accessed also with the SwissRangerSampleGUI exe delivered with the Windows driver and with the demo program SR 3D View exe that can be dowloaded from www mesa imaging ch drivers php If the IP address of the camera is known then this address can be entered for direct opening Under Linux the selection dialog is cons
6. IMAGING 12 Driver installation and setup It is recommended to install the software first and then to plug in the camera The installation procedure is different depending on Operating System and version The different procedures are outlined below The following figure figure 12 1 shows the installation sequence for Windows Vista 32 bit ala Ey 1558 1010550 SetuP y dpi af Baina fo litusbSR 10 10 550 Setup di ap cafum Ms E License Agreement M E S A Welcome to the libusbSR 1 010 550 Please review the license terms before instaling libusbSA MESA c oc weEB Setup Wizard 1 0 10 650 IMAGING IMAGING This wizard will guide you through the installation of Ibusb5 1 0 10 550 Press Page Down to see the rest of the agreement This is the latest driver package for the Swissranger camera It recommended that you dose al other applicatiore before starting Setup This will make it possible to update relevant system files without having to reboot your computer m it contains the driver based on libusb for the Swissranger SR 2A SR 2B SR 3000 SR 3100 SR4k camera the application dll libusbSR dll wth header and source files a helpfile Swiscranger chm sample code fragments libusbSRTasier and SwissrangerSampleGui with source Click Next to continue If you accept the terms of the agreement dick I Agree to cortinue You must accept the agreement to nstall libusb5R 1 0 10 550
7. This is a combination of the flags specified in the enumeration AcquireMode see the HTML API documentation of the SR4000 Many mode flags can be combined with a bitwise OR operation Each possible setting has the form AM_ where the is a placeholder MESA Imaging AG Technoparkstrasse 1 36 8005 Zurich M ESA SR4000 User Manual IMAGING Note that the function overwrites the modes set previously So to set the mode safely a function like the C function srSetMode shown here int srSetMode int currentMode int flag bool onOff int mode currentMode amp flag if on0ff mode flag return mode must be used in order to not overwrite previously set values or default values For instance to set the Median filter on one can write int SR SetMode cam srSetMode SR_GetMode cam AM_MEDIAN true and to disable it int SR SetMode cam srSetMode SR GetMode cam AM MEDIAN false On board image processing The functions SR Set ImgProcBlk and SR SetImgProcBlkVA provide for some image processing blocks that can be enabled on board i e these are executed on the camera s FPGA Functions include histogram computation and variable kernel convolution Please refer to the HTML API description for further information on the usage of this function There the available functions are described in the documentation of the IPBArg enumeration MESA Imaging AG Technoparkstrasse 1 37 8005 Zurich M ESA SR4000 User Manual
8. see section are freezed after recording a stream Y Important When you use the streaming utility be aware that some parameters and settings as described in section 11 2 cannot be changed reverted anymore Thus a file stream is not a full logical replacement for a real camera 11 1 2 Image capture The distance image and amplitude image see chapter 9 are delivered by the functions void SR GetImage SRCAM srCam unsigned char idx int SR GetImagelist SRCAM srCam ImgEntry imgEntryArray in terms of pointers to unsigned short arrays Note that the applications program does not own the data and thus it does not have to release them The functions int SR CoordTrfUinti16 SRCAM srCam short x short y unsigned short z int pitchX int pitchY int pitchZ int SR CoordTrfFlt SRCAM srCam float x float y float z int pitchX int pitchY int pitchZ int SR CoordTrfDbl SRCAM srCam double x double y double z int pitchX int pitchY int pitchZ give pointers to the x y z coordinate vectors per pixel as described in chapter 9 These pointers refer to user allocated arrays Y Important Be aware that the x y and z array pointers refer to user allocated memory When these data are dynamically allocated then the user also has to release free them The functions offer the output in different data types The function SR CoordTrfUinti6 retrieves the original values short for x and y unsigned short
9. 3 m for a 10 m camera Similarly for a camera with a range of 10 m all detectable objects situated at 12m will be folded back at 2 m etc o 2mm Values greater than 5m are folded back into 0 5m range 5m Range Om t 5m 10m 15m Values are folded back into 0 10m range 10m Range In o Om 10m 20m B O Measuring range O O Ambiguous range values are folded back into Non ambiguity range the measuring range At 20 Frames sec 10096 object reflectivity Figure 8 3 Illustration of the Non ambiguity range In the field some applications are limited in range by the geometry of the environment e g a wall in the background at less than 5 m In that case a 5 m camera will deliver reliable results with no artifacts due to objects folded back into the measurement range the same holds for scene with a limited range of 10 m using a 10 m camera When the background is not limited the folding back of far and bright objects will cause problems The solution is to filter those values out by setting an amplitude threshold This filtering works best using a 10 m camera as practice has shown that most objects situated further than 10 m meters have low intensities 8 4 Multiple cameras It is possible to connect multiple USB or Ethernet cameras to the same host computer However in any situation where more than one camera is operating in the same area the illumination of the camera may interfere with other cameras There are
10. The hex value 0x0000 upper 14 bits corresponds to the origin of an intrinsic coordinate system and Ox3FFF corresponds to the full phase radial distance Y Important The last two values Ox3FFE and Ox3FFF do not represent distances but instead indicate saturation MESA Imaging AG Technoparkstrasse 1 23 8005 Zurich M ESA SR4000 User Manual IMAGING 9 2 XYZ Cartesian coordinates The software driver provides a coordinate transform function which converts the raw 14 bit radial distances as explained in the previous section to Cartesian coordinates expressed in meters The calculations are performed by the driver on the host CPU This transformation includes a correction which compensates for the radial distortion of the optics The coordinate system used here is Right Handed with z coordinate increasing along the optical axis away from the camera y coordinate increasing vertically upwards and x coordinate increasing horizontally to the left all from the point of view of the camera or someone standing behind it Figure 9 1 shows the camera s output coordinate system Absolute coordinates MESA Imaging Figure 9 1 x y z as delivered by the camera is given in this coordinate system The origin of the coordinate system 0 0 0 is at the intersection of the optical axis with the front face of the camera Saturated pixels transform to the value 0 0 0 saturation is explained below in section 9 3 More i
11. and Point List different display 3D point display options e Color or Amplitude selection of the 3D overlay source e Cross Section draws a line through a single row and column of the data The position of the line corresponding to Point A may be selected by clicking on the distance O or grays scale image 6 with a left mouse button click The position of point B may be selected on the same images by using the right button The coordinates of the points and the distance are shown on the top left of the 3D area e Background and Load lmage background selection of the 3D area 0 On the right hand side of the screen there is a column marked with 9 with a button Home that resets the perspective changes that were done in the 3D area Furthermore there are the following three pull down menus Display Options Filters and Streaming Only one of these can be opened at a time The three pull down menus and further control keys are described in the following subsections 13 2 1 Display options In the display options the check buttons Grid and Bounding Box draw a gound plane and an indication of a smallest enclosing box with fix orientation The check button Reverse flips the image in terms of the x values mirror effect The radio buttons Orthogonal and Perspective switch between the 3D mode perspective and a mode in which the z values are shown as an orthographic projection of the pixel array orthogonal In the orthogonal model
12. and sunlight 2222s 19 8 2 Avoiding multiple reflections 2 ses 19 bora ds a e deu hot 21 8 4 Multiple cameras lll sss sss 21 MESA Imaging AG Technoparkstrasse 1 2 8005 Zurich M ESA SR4000 User Manual IMAGING 23 9 1 Distance data s s saei s 028i a ewe be we a ew ep hd Red 23 9 2 XYZ Cartesian coordinates 2 llle 24 9 3 Amplitude data la sns 24 9 4 Confidence mara 25 26 10 1 Continuous acquisition Model ss 28 PITT Ux 29 10 2 1 Software trigger model 22s 29 CP TITLE LEM 29 31 11 1 Interfacing functiOnS ss sss 31 11 1 1 Openingandclosing 2222s 31 TET 33 11 1 3 Control parameters for image Capture a e 34 11 2 Parameters affecting measurement quality 2n 34 11 2 1 Integration Time lll sss 35 11 22 Amplitude threshold 2l 35 11 2 3 Modulation frequency ooa 35 Fai Sel nae Ges Arete ie a Se ge ads PEL 36 11 3 Filters and auxiliary functions 2222s 36 12 Driver installation and setup 38 a os Bete eee Gee a ee 39 121 1 Windows i o n doc bcc ae Rok ee OX x1 Pe a do OR Ws 39 Duden d nu wu xpo d Kur II o eR rut ud 39 pda ciedad 39 12 3 Connecting a USB camera lt lt s aln oe xo a PS 40 12 3 1 W hdoWs os ea a wee woke moon Eo xe orc OR e eon WU Hodie ROADS sei 40 12 4 Connecting an Ethernet camera using DHCP or static IP address 2 2 40 12 4 1 Connecting to an SR4000 using DHCP
13. for z in milimeters Furthermore the function SR CoordTrfFlt delivers 32 bit float and SR CoordTrfFlt provides 64 bit double values in meters The pitchX pitchY and pitchZ arguments can be used for different arrangements of the data This is best explained by example The following code MESA Imaging AG Technoparkstrasse 1 33 8005 Zurich M ESA SR4000 User Manual IMAGING int pitch sizeof short short X shortx malloc rows cols pitch short Y short malloc rows cols pitch short Z short malloc rows cols pitch SR CoordTrfUinti6 cam X Y unsigned short Z pitch pitch pitch will give you three separate arrays where the rows of the x y and z data are stored one after another in a long rows times cols time size of one element array Thus the three arrays have the form Xo 0 X0 1 1 Xrows 1 cols 1 Y0 0 YO 1 Yrows 1 cols 1 and 20 0 20 1 Zrows 1 cols 1 Another example is int pitch 3x sizeof short short XYZ short malloc rows cols pitch SR CoordTrfUinti6 cam amp XYZ 0 amp XYZ 1 unsigned short amp XYZ 2 pitch pitch pitch Here the output is one interleaved array of x y and z data x0 0 yo o 20 0 Zrows 1 cols 1 11 1 3 Control parameters for image capture All API functions that can affect the cameras behavior have the form SR Set where is a wildcard The wrappers in the other interfaces Ma
14. host PC This time depends on the camera used For Ethernet cameras it is about 20 ms and for USB cameras around 6 ms Too high integration times lead to saturation while to low integration times lead to noise Higher integration times also cause higher temperature of the sensor and therefore the heat sink requirements in section become even more important See chapter 7 for a more detailed explanation of these interdependencies The function SR GetIntegrationTime retrieves the current integration time 11 2 2 Amplitude threshold The parameter amplitude defines a minimum amplitude that needs to be exceeded in order to accept a measurement This parameter can be used to suppress values with low amplitude that might be unstable The amplitude threshold can be set with int SR SetAmplitudeThreshold SRCAM srCam unsigned short val where the value val ranges from 0 to 216 1 The effect is that the distances and the x y z values of a pixel with a lower amplitude than val are all set to zero For static scenes the reflected signal amplitude can be used as a measure of the quality of corresponding distance measurements alternatively to the confidence value In contrast to the confidence map the amplitude image needs no extra processing resources The function SR_GetAmplitudeThreshold retrieves the current amplitude threshold The default value is zero 11 2 3 Modulation frequency The parameter modulation frequency can be set w
15. m 100 Extract sr_sinplegu fig 100 Extract helptoc xml 100 Created uninstaller C Program Files Mesalmagina Swissranaer Uninstall exe Create shortcut C ProgramData Microsort windows Start Menu Programs Mesalma a a SRAK SR3K SR2 E Show SwissrangerMainDoc html pad Cancel Figure 12 1 The sequence of steps from left to right in each row from top to bottom over the rows that installs the software on windows MESA Imaging AG Technoparkstrasse 1 38 8005 Zurich M ESA SR4000 User Manual IMAGING 12 1 Installing driver demo and sample software Supported operating systems are the Windows 32 bit platforms XP Vista 7 A beta version of a Linux driver is also available but driver updates will be done on a less regular basis compared to the Windows driver 12 1 1 Windows The Setup program may run automatically when the CD is inserted If not run the Installer e g SwissrangerSetup1 0 10 550 exe from the root menu of the CD Alternatively run an updated version of the Setup file downloaded from the Mesa website http www mesa imaging ch drivers php On Windows Vista 7 some security confirmations must be given by the user during the installation process After successful start of the installer the sequence shown in figure previous page can be followed To enable support for Ethernet cameras the Interfaces node must be expanded and the Ethernet check box c
16. the camera parameters dialog box which also allows adjustment of integration time and amplitude threshold Ctrl R performs a left right flip of the displayed images 13 3 Sample Code Example code is provided in C with a simple GUI for Windows in the SwissrangerSampleGUI sample and without GUI for Windows and Linux in the LibusbSRTester cpp console application Some changes may be needed for the code to compile on different development platforms Project files are included for Microsoft Visual Studio 2005 and Makefiles are included for Linux 13 4 Matlab Interface A Matlab interface to the Swissranger is provided for Windows This is installed by default during driver installation to C Program FilesMMesalmagingNSwissrangerMnatlabNswissranger To make the Swissranger interface available within Matlab this path must be added to the end of the Matlab serach path using the Matlab Set Path command The section of the Help file Matlab Interface to Swissranger Cameras contains more information For an overview of the SwissRanger m functions use the command help SwissRanger within Matlab 13 5 C Interface A code example for a C interface is available from www mesa imaging ch temp SwissRanger zip MESA Imaging AG Technoparkstrasse 1 48 8005 Zurich M ESA SR4000 User Manual IMAGING 14 Help and Support For aspects of the setup and operation of the camera refer also to the Knowledge Base and FAQ on the MESA website ww
17. 000 as well as the most important adjustments are explained 13 1 1 Distance image The distance image contains distance values for each pixel Depending on whether the Coord Transf checkbox is checked this is either radial distance from the camera set by default or the z values as described in chapter 9 In the SampleGUI application the distance values are scaled along the color spectrum that is shown in the top of the display area right to the OK button MESA Imaging AG Technoparkstrasse 1 43 8005 Zurich M ESA SR4000 User Manual IMAGING 13 1 2 Grayscale image The illumination striking an object decreases with the square of the distance from the camera to the object Therefore the signal amplitude is much lower for more distant objects The check box Convert Gray activates a mode that compensates for this effect to produce a gray scale image similar to that of conventional gray level cameras When this mode is off this image is simply the amplitude signal see chapter 9 13 1 3 Scaling of display color Below the frame rate textbox is a dropdown control which allows selection of image0 and imagel corresponding to the distance or gray scale image The two edit boxes below this dropdown can be used to set the display s color range The top edit box is the minimum range value Any value at or below the value entered is displayed dark blue The lower edit box is the maximum range value Any value at or above the value entered is d
18. Flight works The distance measurement capability of the SR4000 is based on the Time of Flight TOF principle See e g http en wikipedia org wiki Time of flight for a description of this principle In Time of Flight systems the time taken for light to travel from an active illumination source to IR light reflective objects in the field of view and back to the sensor is measured Given the speed of light c the distance can be determined directly from this round trip time To achieve the time of flight measurement the SR4000 modulates its illumination LEDs and the CCD CMOS imaging sensor measures the phase of the returned modulated signal at each pixel The distance at each pixel is determined as a fraction of the one full cycle of the modulated signal where the distance corresponding to one full cycle is given by c D 7 6 1 where c is the speed of light and f is the modulation frequency At a modulation frequency of 30 MHz this distance is 4 997 m at a speed of light 299792458 m s Therefore 30 MHz cameras are those with the 5 m range in the product specifications and 15 MHz cameras are those with the 10 m range The analog electrical signals are converted into digital values in an Analog to Digital conversion process from which a 14 bit value is calculated This raw output of the camera refers to the spherical distance measure between the pixel on the camera chip and the corresponding region in the environment From the single pixel val
19. I of the driver or one of the interfaces to Matlab or Python On application level sample and viewer programs are available on the software and documentation CD or via download from http www mesa imaging ch drivers php These programs are described in chapter 13 software and can be used to vizualize the camera s data outputs 9 1 Distance data The distance data is given by the phase angle as described previously in chapter 6 This angle is directly proportional to the distance that light travels from the LEDs to the object and back The phase angles for all pixels are available with the API function SR GetImage as a pointer to a 176 144 25344 long array of unsigned short values The data is arranged in this array as a 144 sequence of rows of size 176 The phase angles are output from the SR4000 as 16 bit values where only the upper 14 bits D13 DO see table below are used In table 9 1 the format of the pixel data is shown D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 DO ID1 IDO Table 9 1 Arrangement of the bits composing the distance values The two least significant bits ID1 and IDO in table 9 1 are reserved The distance value d of a pixel is given by o dmax d 214 9 1 where is the 14 bit pixel value encoded by D13 to DO and dmax the maximal full phase distance of the camera on the camera type see chapter 6
20. R4000 is installed are responsible for obtaining and observing all applicable safety regulations and rules e The operating instructions must be made available to the operator of the system where the SR4000 is integrated The operator of the system is to be instructed in the use of the device by specialist personnel and must be instructed to read the operating instructions e The SR4000 is not a device that is certified for safety applications 2 4 1 Electrical installation of the camera Please observe the following items e Only adequately qualified personnel is allowed to install the camera e Only the standard power supply provided by MESA may be used with the camera e Another power supply might only be installed by an adequately qualified personnel In this case following applies The power supply isolation from the ground voltage must be redundant i e double isolated power supply The power supply must be conform to chapter 2 5 of EN60950 1 2006 to ensure fire safety Wire cross sections and their correct fuse protection as per the applicable standards must be implemented All notices from chapter 15 of this document have to be observed MESA cannot be made responsible for any injuries resulting from a faulty power supply design e User must ensure that no significant electrical grounding potential difference might appear between the camera and the network power supply This is particular true for cameras con
21. SR4000 User Manual M ESA SR4000 User Manual IMAGING Contents 1 About this document 5 1 1 Goal of this document 5 1 2 Target group beer eei a A eR a a Red ons 5 1 3 Symbols used in this document 2 0 1 eh 5 6 2 1 Authorized personnel o 6 2 2 Correct use of the camera o a ss 6 2 3 Camera hardware integrity 2 6 2 4 Safety notes and protective measures oao a a 6 2 4 1 Electrical installation of the camera e o 7 2 42 Eye satety s Ras ee a pem Gr Seek ye RAE GR VOS GM ue AD Rus 8 9 4 General recommendations 10 A cr Lx 10 4 2 Power requirements 10 ede eee ty ye Bs eee ee Ee ee et es 10 5 Package contents 11 5 1 Shipped components 2 2 sss 11 hapa fe Ba eed a Genre ee eee cee Gees eo ee Aye 11 13 6 1 Distance estimation and 3D measurement a a a a a 13 15 7 1 Definition of absolute accuracy and repeatability o a a a 15 7 2 Factors that influence absolute accuracy and repeatability 15 7 2 1 Absolute accuracy ooa a ss 15 1 3 Specified absolute Accuracy and repeatability oa oaa a o 15 7 3 1 About the reflectivity of different materials 15 VPN ME 16 1 4 Movement Artifacts 22s 16 1 5 Setting the optimal integration time 2e 17 19 8 1 Environmental conditions o o a a 19 8 1 1 Temperature aa sss 19 8 1 2 Ambient light
22. a s housing temperature does not exceed 50 C Heat may be drawn away by following measures e Mount the camera to a larger thermal mass provided that the mounting is thermally conductive e Use forced airflow especially if there is any form of enclosure e Use a heat sink with fins e Using longer integration times causes the camera to generate more heat than using short in tegration times In the case that continuous measurement is not needed heat generation may be minimized by using triggered acquisition in chapter 10 the different acquisition modes are explained 8 1 2 Ambient light and sunlight Y Important Direct sunlight will affect the performance The camera should not be used in direct sunlight Indirect sunlight that shines through doors and windows in indoor environments is usually not a problem 8 2 Avoiding multiple reflections Y Important Avoid setups with multiple light paths The total distance traveled by the light is about twice the distance from the camera to the object However it is possible that objects may be arranged in the scene such that light takes a less direct path than this For example the light may be reflected by a first object before being reflected by the measured object and finally return to the camera sensor In this situation the light travels by the direct and also indirect paths hence the term multipath The apparent distance is then a weighted average of the pa
23. acteristics of the scene and objects that are measured To describe the reflectivity of objects two aspects of the reflected light must be considered MESA Imaging AG Technoparkstrasse 1 15 8005 Zurich M ESA SR4000 User Manual IMAGING 1 The proportion of the back scattered light energy compared to the incoming light energy 2 The angular distribution of the back scattered intensities directed reflection versus diffuse reflec tion For diffusely reflecting materials mat and dull surfaces the reflectivity coefficient has values between 0 all incoming light is absorbed or transmitted and 100 such as for a white sheet of paper The reference of 100 is given by the case of a perfect Lambertian reflector where 100 of the light is back scattered with an intensity distribution that is independent of the observation angle For directed reflecting materials such as glossy surfaces Retro reflectors or in the extreme case mirrors the reflection coefficient might be gt 100 for specific angles at which the light is directly reflected Camera measurements are not optimal for such directed reflections as the image might saturate at the angles where all the light is reflected directly into the sensor Another problem is when the reflected beam points away from the camera preventing the sensor from capturing enough signal intensity to deliver stable measurements See table 7 1 for examples of different materials and their reflecti
24. as a separate exposure This means that in order to obtain a phase distance measurement four consecutive exposures must be performed lf an object in the scene moves during these exposures errors may be introduced into MESA Imaging AG Technoparkstrasse 1 16 8005 Zurich M ESA SR4000 User Manual IMAGING the measurements The noise introduced due to movement is random noise at the edges of the object moved 7 5 Setting the optimal integration time In order to set the optimal integration time one has to compromise between 3 aspects 1 The needed acquisition speed 2 The needed measurement quality 3 The type of measured objects The diagram in figure 7 1 shows the interdependencies of these aspects 1 Acquisition Speed 2 Measurement quality A Frame Rate D Measurement stability B Mooving objects C Time budget for measurement Integration time 3 Measured objects E Object reflectivity F Distance object camera Figure 7 1 Diagram showing interdependencies of different parameters In the following enumeration the diagram is explained in more detail 1 Acquisition speed The frame rate at which the images are acquired is inversely proportional to the integration time Setting a smaller integration time will result in A Higher frame rate B Less movement artifacts from moving objects C Minimizing the time budget needed for the overall measurement e g measurements that involve image processing on a se
25. ate heat sinking The requirements for heat sinking depend on the environment and application The essential requirement is that sufficient heat is drawn away from the camera to ensure that the temperature of the camera housing does not exceed 50 C Heat may be drawn away by mounting the camera to a larger thermal mass provided that the mounting is thermally conductive by using forced airflow especially if there is any form of enclosure or by using a heat sink with fins if a static system is required Longer Integration Times see chapter I1 for an explanation of the integration time parameter cause the LEDs to be active for longer periods resulting in more heat To reduce the amount of heat generated and power consumed it may help to use Triggered rather than the Continuous mode see chapter 10 4 2 Power requirements Y Important For the camera to operate with the precision as described in the specifications it must be powered with 12 V DC Min 2 Max 10 If the minimal voltage is not supplied the camera will have less precise measurements If the camera is supplied with a higher voltage the exceeding energy will be dissipated through heating of the camera which will also influence the camera s precision On demand MESA delivers a closed housing power supply that complies with those requirements but that is not of industrial grade especially in respect to lifetime under demanding conditions For applications
26. bled by default The third filter activated with the FIFO check button is a simple time averaging filter that can be used to improve the measurements in static scenes An editing window right to the FIFO button allows to set the number of past frames that get averaged 13 2 3 Streaming The streaming section of the interface enables the capture of a number of frames of data There are three formats supported e ASCII output of the frames in separated text files see box ASCII format below e AVI Video an AVI video that can be watched with conventional video playing software e g VLC or Windows Media Player e SRS SwissRanger stream as described in chapter 11 This can be opened as a camera in the opening dialog ASCII format The SR_3D_View application can export a data stream from a SwissRanger camera containing 3D point coordinates and amplitude data Each captured range image in the sequence is saved in a separate file with the filenames being numbered name_0001 dat name_0002 dat etc Within each file z x and y coordinates are arranged as arrays of 144 rows of 176 tab delimited floats Coordinates are in meters The coordinate system is Right Handed with z being the distance along the optical axis from the front face of the camera and from the camera s viewpoint x increasing to the left and y increasing upwards with zero x and y lying on the optical axis This is followed by 144 rows of 176 tab delimited ints for the amp
27. d by dividing the full phase lengths by 214 The real spherical distance in mm can in be obtained by multiplying the 14 bit phase measure with the factor of 0 305 mm or 0 61 mm respectively From this distance together with the intrinsic parameters of the camera x y and z coordinates per pixel are computed This is done inside the camera so that it delivers full 3D coordinate vectors for each of the 176 times 144 pixels MESA Imaging AG Technoparkstrasse 1 14 8005 Zurich M ESA SR4000 User Manual IMAGING 7 Measurement performance 7 1 Definition of absolute accuracy and repeatability To characterize the precision of a camera a statistical approach is used For an object at a given known distance repeating the distance measurement with the camera will result in a distribution of measured values centered on a mean value Absolute accuracy is the difference between the mean measured value of the distribution and the real value and represents the maximum systematic error on the distance measurement This value is particularly relevant for the precision on absolute distance measurement Repeatability is characterized by the spread 10 of the measurement around the mean value and is relevant to characterize the precision on a single measurement This value gives an indication on the noise of a given measurement 7 2 Factors that influence absolute accuracy and repeatability Repeatability Repeatability noise of distance measureme
28. done Camera File Stream Y Vibusb0 0001 0x1ad2 0x0075 3D SR4000_ Serial 400001d1 Figure 13 2 Open dialog select a camera or a file stream with a mouse click The camera text must be blue backgrounded in order to proceed A dialog will appear showing the available Swissranger cameras see figure above In this example there is one USB camera listed and selected An already connected Ethernet camera is marked with a Note that Camera File Stream is used to replay camera data files previously recorded using another application To proceed select a camera from this list and click Connect or simply double click Y Important If the camera has already been connected the camera selection dialog box will not appear The application will automatically connect to the same camera as the previous time if this camera is available In order to force the dialog box to open one must select the Open force dialog in the File Menu of the GUI To start acquisition click the acquire button Acquire The camera will now start continuous acquisition with the acquired images being displayed in the application window The images are displayed in false color with a color bar above them which indicates the color scale from blue zero or minimum to red fullscale or maximum Below the buttons Acquire and Close the frame rate is displayed In the next section the different types of image data produced by the SR4
29. e unit without connecting the Ethernet cable e Wait 20 seconds before plugging in the network cable The camera now has a fixed IP address of 192 168 1 42 The camera cannot function normally using this address the only purpose is to set another static IP address In the following the tool Telnet wil be used This is not enabled by default on Windows platforms Here are the instructions to do this 1 Start Control Panel Programs and Features 2 On left side select Turn Windows features on or off 3 Check Telnet wait until it has been installed Start now a command prompt or equivalent console Windows Vista users see note on Telnet below 1 Telnet to the camera telnet 192 168 1 42 MESA Imaging AG Technoparkstrasse 1 40 8005 Zurich M ESA SR4000 User Manual IMAGING 2 set the static address e g fw setenv staticip 192 168 1 33 Exit telnet and repower the camera with the network cable connected The camera will always use the static address on power on when attached to a host PC or network 12 4 3 Reverting to DHCP To set the camera to use DHCP again the static IP address must simply be cleared as follows 1 Telnet to the camera e g using the fallback address mode as described above telnet 192 168 1 42 2 clear the static address fw setenv staticip no argument clears any existent IP Exit telnet and repower the camera with the network cable connected The camera will always use DHCP to get an address on power on w
30. echnoparkstrasse 1 8005 Zurich 11 M ESA SR4000 User Manual IMAGING Illumination cover Optical filter Figure 5 2 Front view of SR4000 The following components are shown in figure 5 2 e Illumination LED cover This protects the LEDs while allowing their light to be transmitted e Optical Filter This allows only light of wavelengths near that of the illumination LEDs to pass into the camera lens Views of the SR4000 from the back and below are shown in figure Power connector Status indicator LED Mounting hole as Trigger connector USB connector Figure 5 3 Back view showing connectors and view from below showing mounting holes The following components are shown in figure 5 3 e Power connector For supply of 12 V DC at up to 1A to the camera e Trigger connector For external hardware triggering of image acquisition e Data Connector USB in this case For connection to PC e Status LED Flashing slow power on Flashing fast acquiring images e Focus adjustment The focus is pre set at the manufacturer s place to 1 6 m Objects from 0 5 m to 4 4 m will be in focus e Mounting holes Precise and robust mounting of the camera can be made through four M4 holes and two additional 4H7 holes In addition it is possible to screw the camera onto standard tripods usually used for photo cameras MESA Imaging AG Technoparkstrasse 1 12 8005 Zurich M ESA SR4000 User Manual IMAGING 6 How Time Of
31. ew application is installed by default when installing the driver from the CD Alternatively it may be downloaded from the Mesa Imaging website at http www mesa imaging ch demosoftware php This software depends on DirectX being installed on the host PC version 9c minimum To connect to a SwissRanger camera click the Start button Start In order to enter the opening to select a camera manually dialog hold the Ctrl key and press the button Start The button Start will change to Stop as can be seen in figure 9 B SwissRanger 3D Viewer Application 112120 Mesa Imaging AG Debug Build libMesaS amp dll 10141 Display Options 2 Denda Bounding Box Reverse OPerspective Dosallate 50 Point Size Orthogonal Gray Level Is Jampl Corr Cursors Clcross secton Cisp center exe Min 0 00 Figure 13 3 The SR_3D_View Interface showing distance gray scale and confidence map images on the left hand side and 3D projection in the main window There are a few control items below The integration time can be adjusted with an edit window below Camera Settings to avoid saturation and to achieve the desired balance between low noise and high frame rate The check button Auto activates the auto exposure function see also chapter 11 that adapts the integration time on line Further controls on the left side of the window include a confidence threshold and fre
32. g described above Also the API function SR ReadSerial can be used to read the serial number Opening from a file stream Another option for opening is to open a SwissRanger stream SRS The function int SR OpenFile SRCAM srCam const char filename can be used to open a previously recorded stream This stream behaves similar as a camera to serve for the following purposes e Development of recognition or general application programs without the availability af the actual camera MESA Imaging AG Technoparkstrasse 1 32 8005 Zurich M ESA SR4000 User Manual IMAGING e Reproducible camera tests on reference streams The user can store golden data e g detection results in terms of image coordinates into a separate file The SwissRanger file stream and the golden data file can be used for benchmarking in the development cycle e Simulation mode e g for unit tests The difference to a real camera is that all settings that affect the raw pixel data running on the camera cannot be reverted see also section 11 2 The API function int SR_StreamToFile SRCAM srCam const char filename int mode can be used to record a stream Also the sample and demo programs see chapter 13 can be used for recording SRS streams The function opens a file and streams received data from the camera to that file on each image acquisition Again it should be noted that those settings which affect the pixel data and that are run on the camera
33. has been completed The hardware trigger output is in active state for the duration of the acquisition and readout and the falling transition of the hardware trigger output indicates that this phase is complete Hardware trigger output a acquisition and readout calculation T ooo Figure 10 4 Schematic view of the software triggered mode SR_Acquire SR Acquire output 10 2 2 Hardware trigger mode When hardware trigger mode is enabled the camera waits for an external hardware trigger When the trigger signal is received the image acquisition starts The Acquire command is then used to initiate transfer of the image to the host computer When the command completes the image is available The hardware trigger output is in active state for the duration of the acquisition and readout and the falling transition of the hardware trigger output indicates that this phase is complete MESA Imaging AG Technoparkstrasse 1 29 8005 Zurich M ESA SR4000 User Manual IMAGING Hardware trigger output acquisition and readout calculation Y hardware trigger re E o g f 2 a G SR Acquire SR Acquire Figure 10 5 Schematic view of the hardware triggered mode Hardware triggered image capture may be parallelized subject to the fol
34. hecked 12 1 2 Linux The installation packages may be found on the CD under Linux Alternatively please go to the Mesa Imaging Website for the latest installation packages and instructions on how to install the Swissranger software on your system http www mesa imaging ch drivers php 12 2 Uninstalling and reinstalling the driver software Sometimes issues with the driver software can be solved by reinstalling the driver or installing an updated driver version Before doing either it is important to unplug the camera and uninstall the driver software This is done as follows 1 Select Start Programs Mesalmaging SwissRanger Uninstall and follow the uninstall wizard see figure below 2 The driver may then be reinstalled as described above Tft libusbSR 1 0 10 506 Uninstall lee M ESA Welcome to the libusbSR 1 0 10 506 s lt Lave Y Uninstall Wizard IMAGING This wizard will guide you through the uninstallation of libusbSR 1 0 10 506 Before starting the uninstallation make sure libusbSR 1 0 10 506 is not running Click Next to continue SR4K SR3k SR2 Gon Figure 12 2 Uninstall wizard MESA Imaging AG Technoparkstrasse 1 39 8005 Zurich M ESA SR4000 User Manual IMAGING 12 3 Connecting a USB camera The power and USB may be connected in either order Once power is connected the green Indicator LED will start flashing slowly which indicates that the camera has successfull
35. hen attached to a network with a DHCP server When using DHCP or static IP the addresses of the connected cameras are visible in the Camera Selection Dialog Box of the software applications as described in the next section Windows Vista Setting a static IP address on the host PC 1 Start Control Panel Network and Sharing Center 2 Right Click on your Local PC Name This Computer Properties 3 Select Internet Protocol Version 4 TCP IPv4 Click Properties 4 Select radio button Use the following IP address 5 Set IP Address e g 192 168 1 xx where xx is any other than 42 to communicate with a camera using the fall back address 6 Click on Subnet mask to apply default of 255 255 255 0 7 Click OK 8 Click Close 12 5 Silent Install in Windows Sometimes one wants to install the driver in Windows silently i e without the user feedback required A so called silent install can be done by the command SwissrangerSetup1 0 14 653 exe S The number 653 might be different when the latest driver is used the S indicates the silence However newer Windows versions require for the confirmation that you trust Mesa Imaging as software provider Then the installer needs to be invoked as administrator and a further OK mouse click is required In this case automated silent install can be done with a script Please contact our customer support mailto supportOmesa imaging ch to receive an example of a VBS script Windows MESA Imag
36. ided are cameras close to walls or mounted on top of tables see figure 8 2 Correct Wrong Camera support ra O e gt O Sy w Correct Camera support Figure 8 2 Positioning the camera to avoid reflections The FOV of the camera in light red should not include any objects that has not to be measured and that could result in multiple path reflections MESA Imaging AG Technoparkstrasse 1 20 8005 Zurich M ESA SR4000 User Manual IMAGING 8 3 Non ambiguity range Measurements are subject to a so called ambiguity or a back folding phenomenon that is due to the periodicity of the signal that is used for the distance measurement If objects could be present in the scene at distances which differ by more than the distance corresponding to a full modulation period D see figure 6 1 on page 13 the measurement of their position is ambiguous it could be at x or at X D or even x 2D etc x 4 nD n 1 2 For this reason the full phase distance is referred to as the non ambiguity range that is either 0 5 m or 0 10 m depending on the camera type It follows that in the case of a camera with a measurement range of 5 m any object that is situated further than 5 m and whose intensity is still high enough to be detected by the camera will be folded back into the non ambiguity range e g an object at 7 m will be measured at 2 m one at 9 m at 4 m for a 5 m camera and one at 13 m at
37. ing AG Technoparkstrasse 1 41 8005 Zurich M ESA SR4000 User Manual IMAGING 13 Software applications Once the driver software has been installed and the camera is connected a software application may be used to access the camera In this Quick start section the use of the applications SwissRangerSampleGUI and SR 3D View will be explained 13 1 Using the SwissRangerSampleGUI Application This section applies to the SwissRangerSampleGui application which is available only on Windows However the information is relevant to Linux users also since it describes the types of image produced by the camera and the most important adjustments available to the user SwissRangerSampleGui can be launched from Start Programs Mesalmaging Swissranger Sample SwissRangerSampleGui A notification may appear at this stage advising of a new driver dll version available on the Mesa website This may be downloaded by clicking on the link that appears The SwissRangerSampleGUI Interface is shown in figure File Settings Help Cancel Open IV continuous ome o 50 00 fps Image0 0 00 30000 00 IV Coord Transf Median Filter Auto Exposure Conv Gray Figure 13 1 SwissRangerSampleGui interface prior to opening a camera To connect to a SwissRanger camera click the Open button Open MESA Imaging AG Technoparkstrasse 1 42 8005 Zurich M ESA SR4000 User Manual IMAGING Scan Connect Scanning
38. isplayed dark red All values in between are displayed with the proportional value on the color scale 13 1 4 Important adjustments From the Settings menu select Settings dll dialog This causes a dialog to be displayed which contains two sliders These can be used to control integration time and the confidence threshold Integration time This is the most important camera control available in the demo application The integration time can be adjusted using a slider control in the Settings Settings dll dialog dialog box Adjusting this value controls how long each sensor pixel collects light see chapters 6 and 7 Amplitude threshold Amplitude by itself can be used as a measure of the quality of corresponding distance measurements It can be adjusted using a slider control in the Settings Settings dll dialog dialog box 13 1 5 Acquisition options Below the edit boxes used for the image color scaling are a set of four tick boxes e Coord Transf switches between radial distance and distance along the optical axis z value e Median applies a 3 by 3 median filter to the distance data e Auto Exposure adjusts the integration time depending on the maximum amplitudes present in the image e Conv Gray produces a distance adjusted grayscale image MESA Imaging AG Technoparkstrasse 1 44 8005 Zurich M ESA SR4000 User Manual IMAGING 13 2 Visualizing and capturing 3D data using the SR_3D View Application The SR 3D Vi
39. ith the function int SR SetModulationFrequency SRCAM srCam enum ModulationFrq modFrq where the enumeration type has the following assignment as shown in table MESA Imaging AG Technoparkstrasse 1 35 8005 Zurich M ESA SR4000 User Manual IMAGING modFrg 1 6 8 9 10 11 MHz 30 15 29 31 14 5 15 5 Table 11 1 Type assignment for the modulation frequency selection The modulation frequency can be changed by the user mainly to enable for multi camera operation see section 8 4 on page 21 This may be important in applications where more than camera is used e g to capture a larger scene with the sensors These frequency settings are chosen such that the neighboring frequencies are different enough to avoid mutual interferences but close enough that the camera calibration is still valid However generally the following should be noted Y Important If a camera is used outside it s specified frequency then the specifications given in the product data sheet do not apply anymore as the measures are affected by the modulation frequency 11 2 4 Auto exposure The SR4000 API provides a controller that adapts the IT on line by ensuring that no more than a preset maximum fraction of pixels is saturated This leads to the highest frame rate possible given the saturation constraint The function SR_SetAutoExposure enables for this mode Please refer to the HTML API description for further i
40. litude image Amplitude full scale is Ox7FFF Each array is preceded by a description e g Calibrated Distance indicates the Z coordinate array Calibrated xVector indicates the X coordinate array Calibrated yVector indicates the Y coordinate array Amplitude indicates the amplitude array Confidence map indicates the Confidence Map array If a threshold on amplitude has been applied all 3D coordinates and amplitudes will be zero where the amplitude is below the threshold for the corresponding pixel All formats are recorded with setting a file name by pressing Set Filename followed by Start Streaming and Stop Streaming If an existing file is about to be overwritten there is no warning An SRS stream can be re played by opening the camera file stream option in the opening dialog hold Ctrl and click on Start to enter this dialog 13 2 4 Further controls Capturing single frames The menu option File above O offers a few export functions for single frames A frame may be captured and exported in STL DXF or point cloud format in the following way MESA Imaging AG Technoparkstrasse 1 47 8005 Zurich M ESA SR4000 User Manual IMAGING When the camera is streaming live data the Start button at the top left becomes a Stop button Clicking on this will freeze the data for the most recent frame This may then be exported by clicking on the File menu and selecting the desired format Control keys Ctrl F12 shows
41. lowing timing limitations e A second hardware trigger signal will trigger a new acquisition if it is received after the first image has completed acquisition and readout The hardware trigger output may be used by an external system to detect when the integration is complete e If an Acquire command is not received before the next image has completed integration then the first image is lost e If the previous image transfer has not completed before a second integration completes the second image is lost It is possible to sychronize mutliple SR4000 cameras such that they all capture images at the same point in time Information on how this can be done is available with a support request to mailto support mesa imaging ch MESA Imaging AG Technoparkstrasse 1 30 8005 Zurich M ESA SR4000 User Manual IMAGING 11 Application Programming Interface API overview The camera comes with a C C application programming interface API with interfaces to Matlab and Python available The required data are on the CD shipped with the sensor or via download from http www mesa imaging ch drivers php An example of how to interface from C is available on request contact the customer s support mailto support mesa imaging ch In chapter 12 the installation of the software drivers documentation and samples is described The API is described with a comprehensive HTML documentation Under Windows this is installed by default to
42. n and readout acquisition and readout calculation Y md D o lt a n SR_Acquire SR Acquire Figure 10 3 Schematic view of the continuous acquisition mode Y Important In Continuous Mode because of the 1 frame latency any changes in mode integration time or modulation frequency setting do not affect the first acquired frame after the setting change since this frame would have been acquired before the setting change Y Important For very small integration times the data transfer may not start until the beginning of the second subsequent N 2 frame MESA Imaging AG Technoparkstrasse 1 28 8005 Zurich M ESA SR4000 User Manual IMAGING 10 2 Triggered acquisition modes When software trigger mode is enabled the camera does not capture an image until a trigger is received The following two cases are possible 1 Software trigger mode 2 Hardware trigger mode These modes are described in the following subsections 10 2 1 Software trigger mode When hardware trigger mode is disabled the camera waits for an Acquire command When the command is received the image capture starts Once acquisition is complete the image is processed in the FPGA and then transferred to the host computer On completion of the transfer the command completes The acquired image is then available A new acquisition will only start when the data transfer
43. nected to Ethernet networks that span over different physical buildings e Observe the current safety regulations when working on electrical systems e Do not open the housing MESA Imaging AG Technoparkstrasse 1 7 8005 Zurich M ESA SR4000 User Manual IMAGING 2 4 2 Eye safety The sensor emits light actively Therefore rules and laws related to active light emitting technical devices apply The following statements hold for the SR4000 e TheSR4000 operates with 24 LED emitting in the 850 nm range e The SR4000 is certified LED Class 1 according to EN 60825 1 2002 eye safe MESA Imaging AG Technoparkstrasse 1 8 8005 Zurich M ESA SR4000 User Manual IMAGING 3 Environmental protection The camera contains electronic components When you dispose it pay attention to the following recom mentations e Always dispose unserviceable or irreparable devices in compliance with local national rules and regulations on waste disposal e Dispose of all electronic assemblies as hazardous waste The electronic assemblies are straightfor ward to dismantle MESA Imaging AG Technoparkstrasse 1 9 8005 Zurich M ESA SR4000 User Manual IMAGING 4 General recommendations 4 1 Heat sink requirements Y Important Provide for suitable heat sinking as explained in this section When the SR4000 is in use especially when it will be operating for long periods it is important to ensure that there is always adequ
44. nformation about the visualization of the camera outputs are given in chapter software and the software interfacing is described chapter 11 API description Y Important The coordinate system used by the camera is not the same as usually used in the literature on perspective camera projection models These systems lie in the center of lens about 11 mm from the front plate into the housing and the x and y are rotated around z positively about 1 2 If you want to retrieve the exact system for your camera including all projective camera parameters then contact mailto supportOmesa imaging ch A program that outputs these parameters for a specific camera is available 9 3 Amplitude data Amplitude data quantity A in figure 6 1 on page 13 is output as an array of 16 bit words arranged like the distance values described in section Again only the 14 most significant bits are used The largest 14 bit value of Ox3FFF indicates saturation Values from 0x000 to Ox3FFE are proportional to the received amplitudes Bits ID1 and IDO are reserved This arrangement is shown in table 9 2 on the next page MESA Imaging AG Technoparkstrasse 1 24 8005 Zurich M ESA SR4000 User Manual IMAGING A13 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 AO ID1 IDO Table 9 2 Arrangement of the bits composing the amplitude values By default the amplitude is con
45. nformation on the usage of this function 11 3 Filters and auxiliary functions Filter modes Some filters and auxiliary functions are provided e Median filter AM MEDIAN This turns on a 3x3 Median filter see e g http en wikipedia org wiki Median filter to understand a Median filter Note this algorithm is run on the host PC and not on the camera By default this mode is disabled e Convert gray mode AM CONV GRAY This mode compensates for the light intensity send out by the sensor itself The resulting image is more looking like a conventional passive gray level camera image This mode is processed on the host PC and requires for some processing power The mode is set to active by default e Confidence map AM CONF MAP This flag has to be enabled to compute the Confidence Map see section 9 4 on page 9 4 for a description of this map Only when this mode is set then the confidence image is available with a call to SR_GetImage By default this mode is disabled e Adaptive Neighborhood Filter AM_DENOISE_ANF This value turns on a hardware implemented noise filter This filter combines amplitude and distance information in a 5x5 neighborhood It reduces noise while preserving detail such as edges or small structures with no computational cost to the host CPU The filter is active by default All these modes are set with the function int SR_SetMode SRCAM srCam int mode that takes the argument mode of type int
46. nts depends mainly on signal amplitude and background illu mination Signal amplitude in turn depends on object distance and object reflectivity see section 7 3 1 The optimal repeatability is achieved when the integration time is set to give the greatest Amplitude without reaching saturation The repeatability noise of distance measurements is often improved using some form of temporal or spatial averaging 7 2 1 Absolute accuracy Absolute accuracy on the other hand is independent of distance and reflectivity The absolute accuracy is achieved internally in the SR4000 through a combination of elements including pixel and electronics architectures an optical feedback loop and temperature compensations In nominal operation an absolute accuracy of lt 1 cm is achievable see specification or data sheet for more information 7 3 Specified absolute Accuracy and repeatability Every camera type has a data sheet that gives more details about the guarantied absolute accuracy and repeatability Please refer to this document for the specifications of your camera As described before the reflectivity of the measured object has a large influence on the repeatability of the measurement This is the reason why it is important to understand how the reflectivity of an object is defined and how it can be measured 7 3 1 About the reflectivity of different materials The measurement characteristics of the camera highly depend on the reflection char
47. ole based Direct opening The camera can be started directly without any user feedback required using SR OpenETH or SR OpenUSB Which of these you have to use is depending on the actual product If you have an Ethernet type SR4000 then SR OpenETH needs to be called with the IP address as parameter const char addr There are three ways an IP address can be provided to the camera e By default the IP address is requested from a DHCP server In the upcoming selection dialog on SR_OpenD1g described above the IP address is shown in the camera list When there are more than one cameras found then you can identify the camera of interest by comparing the serial number SN printed on the backside of the housing to the MAC addresses in the selection dialog These are equivalent e If the camera is booted up without any Ethernet cable plugged in it enters a special mode where the so called fall back IP is used after about 20 seconds In order to connect to the camera with this IP address you have to follow the recommendations given in section on page 40 The fall back IP can be used to set a static IP address In the case that a static IP address is set on the camera this address must be used to open the camera In case you have an USB type camera you can open with the function SR OpenUSB It takes as argument the serial number of the camera This number is printed on the back of the housing or it can be retrieved by the opening dialo
48. quency selection The confidence threshold can be changed to suppress lower confident pixel values The frequency can be changed to change the full phase distance However note that the camera is not calibrated for frequencies other than its nominal frequency As shown in figure 13 3 the distance 9 gray scale 8 and confidence map O images will appear on the left hand side of the main window Those images are unadjusted raw pixel arrays whereas the 3D projection of the central image O has been adjusted by the coordinate transformation function in the driver to compensate for radial distortion in the optics removing the pin cushion effect Here the full x y z coordinate vectors are displayed The coloring of the points can be selected as a color MESA Imaging AG arkstrasse 1 45 8005 Zurich Technop M ESA SR4000 User Manual IMAGING proportional to the z value of a pixel see the color bar O that shows the color spectrum from zero to full phase distance or as amplitude values The 3D representation in the large center screen 6 may be oriented by holding the left mouse button while moving horizontally or vertically or by using the cursor control keys Zoom is controlled by the mouse scroll wheel or Page Up Page Down keys For a summary of the main controls press the F1 key Elements of the main window may be configured from a menu which is activated by a right mouse button click These are e Solid Wire Frame
49. r In 45V 55V 15mA Start acquisition external voltage level 3 Trigger Out 45V 55V Frame ready to fetch 4 External GND In reference to External Voltage For more details on the trigger logic please refer to chapter 10 section 10 2 1 on page MESA Imaging AG Technoparkstrasse 1 50 8005 Zurich M ESA SR4000 User Manual IMAGING TRIGGER SIGNALS External Signals Internal Signals External Supply VCC VCC 5VDC 10 max 10mA Trigger In lt IN 4 5 5 5VDC max 15mA referenced to external supply GND Trigger Out OUT 4 5 5 5VDC level defined by external supply g External Supply GND GND Figure 15 2 Schematic view of the hardware trigger logic MESA Imaging AG Technoparkstrasse 1 51 8005 Zurich M ESA SR4000 User Manual IMAGING 16 Ratings and conformance Please refer to the official data sheet or specification sheet of your product MESA Imaging AG Technoparkstrasse 1 52 8005 Zurich
50. rical installation configuration maintenance and usage of the SR4000 TOF cameras 1 2 Target group This Manual is addressed to technicians engineers with sufficient skills to understand it and to apply all relevant measures steps to ensure safe usage of the SR4000 according to the manual instructions and according to the safety regulation in place in the specific country where the camera is used 1 3 Symbols used in this document Y Important A note important indicates important information that the reader must understand follow Such a note is in most of the cases related to optimizing the measurement performance of the camera MESA Imaging AG Technoparkstrasse 1 5 8005 Zurich M ESA SR4000 User Manual IMAGING 2 Safe usage of the camera This chapter addresses topics related to the safety of the operation of the camera Every camera user must read this chapter carefully before working with the SR4000 2 1 Authorized personnel Y Important The SR4000 must be installed and used by adequately qualified personnel only Personnel is only considered as qualified if it has sufficient skills to understand and to apply all relevant measures steps to ensure safe usage of the SR4000 according to the manual instructions and according to the safety regulation in place in the specific country where the camera is used 2 2 Correct use of the camera The SR4000 is a measurement device that allows capturing 3D da
51. ries of images 2 Measurement quality MESA Imaging AG Technoparkstrasse 1 17 8005 Zurich M ESA SR4000 User Manual IMAGING D The noise on the measurement 1 0 is inversely proportional to the integration time longer integration times allow to capture a larger amount of reflected light which results in lower noise also described as higher repeatability 3 Type of measured objects E The amount of light that is reflected from the measured objects is proportional to their reflec tivity in the infrared domain Thus to reach the same measurement quality repeatability a higher integration time needs to be set for low reflective objects than for high reflective objects F The light intensity decreases with the scare of the traveled distance Thus to reach the same measurement quality repeatability objects located further away need a higher integration time than objects located closer to the camera MESA Imaging AG Technoparkstrasse 1 18 8005 Zurich M ESA SR4000 User Manual IMAGING 8 Physical setup 8 1 Environmental conditions The camera should be mounted securely in free airflow for cooling free from vibration with care taken to ensure the conditions as specified in this chapter in order to ensure precise and stable measurements 8 1 1 Temperature Y Important The camera must always be mounted to allow sufficient heat to be drawn away from the camera The requirement is to ensure that the camer
52. s of the reflected light are acquired and read out by the sensor The recombination of the information from the four samples is done in the calculation phase The output of the calculation are range values per pixel This data is finally transferred to an external device computer Figure 10 1 Schematic view of the image acquisition process Two modes of image acquisition are supported 1 Continuous acquisition mode 2 Triggered acquisition mode also called single shot mode In that mode the acquisition may be triggered by either a software or a hardware trigger Two types of hardware trigger modes are available on the camera e Trigger In triggers the start of the acquisition and the data output e Trigger Out signal that is emitted in order to synchronize external devices The setting of the trigger modes is described in the API documentation or in chapter 11 In figure 10 2 on the next page an overview of the different trigger modes that the SR4000 supports is shown MESA Imaging AG Technoparkstrasse 1 26 8005 Zurich M ESA SR4000 User Manual IMAGING SR4k Trigger Map OUT from camera Image acquisition readout and calculation triggering acquisition and readout of sensor as well as following calculation Triggered continuous single shot readout sensor as soon as previous readout stopped is TE ih trigger hardware trigger by trigger by SR Acquire Transition hardware signal Fig
53. ta of IR light reflective objects in the surrounding scene The camera can be used by itself or can be integrated into a larger system that uses the 3D Data delivered by the camera Y Important In case of any other camera usage other than stated above any claims against MESA Imaging AG will be rendered void The camera must be used in environments that are adapted to the camera enclosure rating 2 3 Camera hardware integrity By opening the camera or by modifying the camera hardware the declaration of CE conformity the safety as well as the warranty of the camera will be rendered void MESA Imaging AG cannot be made faulty responsible of any financial loss or injuries to users from cameras that have been opened or modified Y Important Under no circumstances is it allowed to open the camera or to make any changes to the camera hardware 2 4 Safety notes and protective measures Please observe the following items in order to ensure the correct and safe use of the SR4000 e The notices in this document must be observed e When operating the SR4000 the national local and statutory rules and regulations must be observed In particular following regulations must be observed MESA Imaging AG Technoparkstrasse 1 6 8005 Zurich M ESA SR4000 User Manual IMAGING the work safety regulations safety rules other relevant health and safety regulations e Manufacturers and operators of the system on which the S
54. th MESA Imaging AG Technoparkstrasse 1 19 8005 Zurich M ESA SR4000 User Manual IMAGING Camera Overestimation due Direct path to multiple path Multiple reflections path Figure 8 1 Multiple path reflections on a concave scene in that case a corner between two walls distances weighted by the strength of signal returned via each path The end result is that distance measurements are over estimated A common situation of multipath appears when measuring objects that have concave structures A good example is when measuring a scene with a corner between two walls In that case the region of the wall right next to the corner will be seen further away than it is in reality see figure 8 1 orange line This is due to the fact that a large portion of the IR light is reflected on the neighbor wall first wall B then on the measured wall wall A into the camera Maximum overestimation is in the region where multiple reflection path are both maximum in number and in intensity This explains the shape of the measured values as shown in orange on figure 8 1 right hand side In order to avoid as much as possible multipath problems the camera should be placed at the greatest distance possible form other interfering objects form which light might be reflected Ideally the Field of View of the camera should not include any objects that have not to be measured Two frequent setups that might cause problems and that have to be avo
55. the z values can be stretched and shifted by holding the Shift key stretching or the Ctrl key shifting together with the left mouse and horizontal mouse movements The check button Oscillate makes the scene moving automatically and periodically left and right for demo purposes The slider Point Size adjusts the size of the 3D points drawn in the 3D area 0 Two sliders below Gray Level control an amplitude offset and scaling that affects the grays scale image on the left of the screen The check button Ampl Corr automates this adjustment There are two 3D cursor control items The Cross Section enables for the same functionality as is available in the right mouse click context menu The Disp Center offers to change the 3D center of rotation Color scaling for color coded distance is selected using left mouse button and a drag and drop mechanism applied to the top and the bottom of the vertical color bar O right to the 3D display HOME on the keyboard brings the 3D scene back to the default view MESA Imaging AG Technoparkstrasse 1 46 8005 Zurich M ESA SR4000 User Manual IMAGING 13 2 2 Filters The filter options allow for three kind of filters First the Median check button applies a median filter with a 5x5 neighborhood Second the ANF activates an adaptive neighborhood filter This filter takes into account a stability measure computed on the local neighborhood of a pixel The median and the AMF filter are both ena
56. tlab Python etc have similar naming conventions This subsection describes the parameters that set different control modes There are different functions related to the control and software embedding With the function SR SetMode described in the previous subsection see subsection 11 3 the flags AM HW TRIGGER and AM SW TRIGGER these are part of the enumeration AcquireMode can be used to switch between one of the triggered capture modes that are described in chapter 10 The functions SR SetCallback and SR GetDefaultCallback are related to a callback mecha nism that gives the user s process control in case of any exceptions This means that possible occurrences of error message boxes are suppressed So if you want to program an application which under no cir cumstances gets interrupted by requesting user input then you have to use callbacks to make the boxes disappear Y Important If you want to suppress any user feedback requests e g due to Ethernet problems then use the callback mechanism to suppress the message windows There can be cases where the program flow is blocked For instance when the hardware trigger is used but the actual trigger did not appear prior to a call to SR Acquire In order to cope with such cases the function SR SetTimeout can be used This timeout is used at reading and writing on USB or Ethernet port Any function which communicates with the camera will fail if it exceeds the timeout
57. ues a 176 by 144 pixel depth map is computed 6 1 Distance estimation and 3D measurement Figure 6 1 Time of Flight sampling of returned modulated signal The LEDs in the front of the sensor emit modulated light pulses The modulation signal can be thought of a sinusoidal signal as shown in figure 6 1 As shown in figure 6 1 by the vertical lines the reflected signal is sampled four times in each cycle at 4 period phase shifts i e 90 phase angle Signal B is the mean of the total light incident on the sensor background plus modulated signal and A is the Amplitude of just the modulate signal The phase phi is calculated from the four samples MESA Imaging AG Technoparkstrasse 1 13 8005 Zurich M ESA SR4000 User Manual IMAGING to produce the distance measurement The amplitude A may be used as a measure of quality of the distance measurement or to generate a gray scale image One burst of the modulated signal is sent out for each image and multiple phase shifts are integrated during this time The lengths of the integration process can be adjusted by the user by means of a parameter called Integration Time IT see also section 7 5 and chapter 11 The raw 14 bit values of the spherical distances range from 0 to 16382 0 to Ox3FFE in hex Higher values indicate saturation A single bit increment corresponds to 0 305 mm rounded if 21 for a 5m camera and 0 61 mm rounded for a 10 m camera These values can be obtaine
58. ure 10 2 Trigger map of the SR4000 Trigger IN blue are a group of modes that are used to initiate an image capture Trigger OUT red is an output signal from the camera that activates on the end of an acquisition cycle See the related sections in the text for more details on the trigger signals MESA Imaging AG Technoparkstrasse 1 27 8005 Zurich M ESA SR4000 User Manual IMAGING 10 1 Continuous acquisition mode When software trigger mode is disabled the camera continuously captures images so called continuous acquisition mode While acquisition and readout occurs for one image the previous image is simulta neously processed in the internal FPGA When an Acquire command is received by the driver the most recent image whose processing has been completed by the FPGA is transferred to the host computer In this way a high frame rate is achieved but there is a latency in the output after completion of the acquisition of at least one frame The continuous acquisition mode is not suited for synchronization with external devices as the exact timing of the output of the image is not known externally The hardware trigger output consists of a pulse that starts at the beginning of each new acquisition Every 4 pulse is 1 5 ms long all others are 1ms long The voltage range is 4 5 V to 5 0 V see also chapter 15 Hardware trigger output Pa acquisition and readout acquisition and readout acquisition and readout acquisitio
59. various approaches which can be used to avoid this interference e Sequence the exposures of each camera using triggered acquisition mode A custom software application is required to sequence the cameras The disadvantages of this approach are that MESA Imaging AG Technoparkstrasse 1 21 8005 Zurich M ESA SR4000 User Manual IMAGING the frame rate is significantly diminished for each camera included in the system and that the acquisitions from each camera are not simultaneous The latter may be important when movement is present in the scene e Different modulation frequencies may be used in each camera to enable them to work together with no interference The SR4000 supports several different modulation frequencies For the 5 m range cameras 29 MHz 5 17 m range 30 MHz 5 00 m range x 31 MHz 4 84 m range For the 10 m range cameras 14 5 MHz 10 34 m range 15 MHz 10 00 m range 15 5 MHz 9 68 m range MESA Imaging AG Technoparkstrasse 1 22 8005 Zurich M ESA SR4000 User Manual IMAGING 9 Data output of the camera This section describes the data output of the camera The camera outputs the following data per pixel e distance data phase measure e x y Z coordinate data e amplitudes similar to gray level data e and a confidence map an estimate of reliability All these data are described in the following sections On programming level the data may be accessed using the C C software AP
60. verted into a value which is independent of distance and position in the image array using the following factors 1 A factor proportional to the square of the measured distance scaled to equal 1 at distance of half of the full phase distance 2 A factor which corrects for the drop in strength of the illumination away from the center of the field of view This factor equals 1 at the center and increases with radial distance from the center 9 4 Confidence map The confidence map is generated in the driver of the host PC using a combination of distance and amplitude measurements and their temporal variations lt represents a measure of probability or con fidence of how correct the distance measurement is expected to be Low confidence is typically due to low reflected signal or movement in the scene The Confidence Map can be used to e select regions containing measurements of high quality e reject measurements of low quality e obtain a confidence measure for a measurement derived from a combination of many pixels e estimate an output reliability in recognition algorithms Confidence map data is output from the SR4000 as an array of 16 bit words There is one confidence value per pixel The Confidence Map has a range of 0 0xFFFF with greater values representing higher confidence MESA Imaging AG Technoparkstrasse 1 25 8005 Zurich M ESA SR4000 User Manual IMAGING 10 Image acquisition modes For each image four sample
61. vity Material Reflectivity Material Reflectivity Kodak gray card bright 107 Rough clean wood palette 25 White paper 80 100 Smooth concrete 25 White masonry 85 Kodak gray card dark 33 Newspaper 70 Black rubber tire 2 PVC grey 40 Table 7 1 typical reflectivity values for diffusely reflecting materials at a wavelength of 850 nm and at 90 incidence 7 3 2 Method to determine the reflectivity of targets In order to determine the reflectivity of a surface an object or a target a simple method consists in placing a target of known reflectivity directly next to this surface and to measure under the same angle the relative intensity of the surface compared to the reflectivity of the reference target As reference target one can use Kodak gray cards as they are quasi Lambertian reflectors for the visible light are of constant quality and are worldwide available Kodak R27 Ref 1527795 Nevertheless note that the Kodak gray cards are optimized for visible light and not for the 850 nm wave length at which we are operating Table 7 2 gives a comparison between reflectivity coefficient of Kodak paper for the visible and the infrared 850 nm domain For visible light as indicated by Kodak For infrared light Bright 90 107 1 Dark 18 32 9 Table 7 2 Reflectivity coefficient of Kodak gray cards at 90 incidence 7 4 Movement Artifacts Each of the 4 phase measurement samples see figure 6 1 on page 13 are taken
62. w mesa imaging ch Alternatively you can send a question to the Mesa support team mailto supportOmesa imaging ch MESA Imaging AG Technoparkstrasse 1 49 8005 Zurich M ESA SR4000 User Manual IMAGING 15 Electrical power and trigger connection In case that another power supply is used observe following rules e power supply isolation from the ground voltage must be redundant i e double isolated power supply e select and implement wire cross sections and their correct fuse protection as per the applicable standards e Design a power supply that is conform to chapter 2 5 of EN 60950 1 2006 risk of fire due to electrical dysfunction All cameras include two Lumberg M8 connectors One connects the power supply and another connects to trigger in and output signals The pin assignments are shown in Figure 15 The camera also includes a status LED Regular pulsing of the status LED indicates that the camera is powered fast pulsing of the status LED indicates data transfer between camera and computer STATUS LED POWER TRIGGER IO Figure 15 1 Schematic view of the connectors on the backplane of the camera including numbering of pins Table 15 1 Power Connections 1 12 VDC Min 2 Max 10 Typ 0 8 A 12 V Min 0 6 A Max 1 0 A 2 SHIELD Connect to protective earth 3 GND Ground Table 15 2 Trigger 1 O Connections 1 External Voltage 4 5 V 55V 10 mA defines the logic level of the trigger output 2 Trigge
63. where reliability over time is a key requirement an industrial grade power supply must be used to power the camera MESA does not supply those devices but can suggest some suited devices suppliers if needed send a request to mailto supportOmesa imaging ch 4 3 Cleaning the camera Together the optical filter and the LED cover see chapter 5 form a flat front face which may be cleaned by wiping with a lint free cloth dampened with isopropyl alcohol if necessary or with optical wipes If the front face is dirty with particles that may be abrasive care must be taken not to scratch the surface Y Important Clean the front end with appropriate utilities e g as explained above MESA Imaging AG Technoparkstrasse 1 10 8005 Zurich MESA IMAGING 5 Package contents 5 1 Shipped components A standard SR4000 package contains 1 SR4000 camera USB or Ethernet 2 Software and documentation Installation CD Optionally it may also contain the following items 3 Communications cable USB or Ethernet 4 Power supply unit 5 Power cable 6 Trigger cable The regular and optional items are shown in figure 5 1 SR4000 User Manual O SR4000 camera O Software and documentation CD Communications cable O Power supply unit O Power cable O Trigger cable Figure 5 1 SR4000 package contents 5 2 SR4000 Description The front view of the SR4000 is shown in figure 5 2 next page MESA Imaging AG T
64. y initialized 12 3 1 Windows A toolbar notification see figure below is displayed indicating that the device driver software is installing and then another indicates that the device driver installation has completed successfully Swissranger SR 4000 Device driver software installed successfully Installing device driver software Click here for status Figure 12 3 This note appears after successful installation in Windows If the device driver has installed successfully any connected cameras will appear in the device manager under the category LIbUSB Devices Note that this applies to USB cameras only 12 4 Connecting an Ethernet camera using DHCP or static IP address The order in which power and network cables are connected is important for Ethernet SR4000 since this determines whether a fall back IP address is used or the normal DHCP or static address 12 4 1 Connecting to an SR4000 using DHCP SR4000 Ethernet cameras are shipped with DHCP enabled by default Simply connect the camera to a network which has a DHCP server and then apply power to the camera The camera obtains its address via DHCP 12 4 2 Setting a static IP address Instead of using DHCP it is possible to set a static IP address In order to do so it is necessary to set the static IP address of the host PC first In order to set the static IP address of the camera it is necessary to use a fixed fall back address e Apply power to th

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