CeX3D Inverse: User`s Manual Command Line Version
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1. export0Obj false If specified as true a 3D model is exported in OBJ format otherwise it is not Whenever an OBJ file is generated a corresponding mtl file is also generated for specifying the texture of the object CeX3D Inverse NCU has the limitation that a reconstructed 3D model may only be exported into one format each time a 3D reconstruction is performed The Wavefront OBJ format is one such format To export into multiple different formats with CeX3D Inverse NCU it is necessary to run the reconstruction mul tiple times With CeX3D Inverse Pro any number of formats may be exported for the same 3D reconstruction 1 3 2 Option exportRib The option exportRib specifies whether or not to export a reconstructed 3D model in RenderMan RIB format It may be specified as either true or false i e by writing exportRib true or exportRib false If specified as true a 3D model is exported in RIB format otherwise it is not RenderMan is a registered trademark of Pixar Animation Studios Whenever a RIB file is generated a corresponding sl file currently always named simpleUvTexture sl is also generated for specifying the texture of the object CeX3D Inverse NCU has the limitation that a reconstructed 3D model may only be exported into one format each time a 3D reconstruction is performed The RenderMan RIB format is one such format To export into multiple differ ent formats with CeX3D Inverse NCU it is necessary to run the rec2. bend inwards similar to the edges of a pillow or a cushion The value 0 0 is default and corresponds to no distortion The values 0 25 and 0 25 are quite extreme distortion values and they are not likely to occur in practice for ordinary cameras and lenses Fisheye lenses may come close to 0 25 or even lower but such extremes of lenses are currently not supported Cameras typically have a distortion that corresponds to a radial distortion hint of between 0 03 and 0 03 Hence e g 0 02 could be a good hint value This is specifed by radialDistortionHint 0 02 The radial distortion however depend on which camera is used particularly its lens on how its zoom settings are as well as slightly on focus settings using autofocus makes this somewhat uncontrollable Typically when the camera is zoomed out the distortion is more negative e g 0 02 or lower When zooming in the distortion gets closer to zero or even becomes positive depending on the lens and camera Currently the most frequent point of failure in the reconstruction is the radial distortion estimation and for this reason you may want to try the reconstruction with several different values for radialDistortionHint By default the actual estimated radial distortions are shown during reconstruction see the option showDistortion which may give you an idea of how the actual radial distortion is by comparing the estimated distortion values with the quality of the recon
3. than 1000x1000 pixels it may be desirable to use a higher resolution i e a lower value The option pixelsPerPoint specifies roughly how many pixels in both height and width of a small square area are used in the final reconstruction for each point on the 3D model Thus when using a value of 4 an area of 4x4 pixels is used for roughly each point on the reconstructed 3D model Hence the resolu tion of the high resolution model depends on both the option pixelsPerPoint as well as the resolution of the input images The default value for the option pixelsPerPoint is 4 Supported values are currently 1 2 4 8 and 16 An example is thus to specify pixelsPerPoint 8 1 3 6 Option radialDistortionHint Photographs taking with an ordinary camera normally have radial distortion due to the camera lens CeX3D Inverse has to estimate this radial distortion To help it in this estimation you may provide a hint of the expected typical radial distortion in the images which is done by specifying a value for the radialDistortionHint option Supported values are in the range 0 25 to 0 25 Negative values correspond to a barrel distortion so named because when straight lines in the real world occur near the edges of the image with this distortion those lines bend outwards similar to the silhouette of a barrel Positive values correspond to a pincushion distortion where straight lines occurring near the edges of the image
4. to either true or false the default being false If this option is specified as showLicense true the End User License Agreement is shown When this option is false the license is not shown 1 3 10 Option showLicensee The option showLicensee may be specified to either true or false the default being false If this option is specified as showLicensee true the user s license information for the software is shown which includes information like name affiliation address and the type and number of licenses When this option is false the user s license information is not shown Notice though that a short summary of the license information is normally always shown when starting a reconstruction 1 3 11 Option showProgress The option showProgress may be specified to either true or false the default being true If this option is specified as false a progress bar consisting of dots is shown during reconstruction The reconstruction is complete when a line of 80 dots is shown which normally corresponds to the length of one line in a terminal or command prompt window If this option is specified as showProgress false the progress is not shown during reconstruction 1 3 12 Option stdErrProgress The option stdErrProgress may be specified to either true or false the default being false If this option is specified as stdErrProgress true progress values will be sent to the standard error stream notice that al
5. CeX3D Inverse User s Manual Command Line Version Hardcore Processing April 12 2015 1 CeX3D Inverse User s Manual Command Line Version The following are online links for manuals and tutorials for CeX3D Inverse e http www cex3d net inverse documentation manuals installation html Installation Guides e http www cex3d net inverse documentation manuals usergui html User s Manual GUI Version e http www cex3d net inverse documentation manuals usercmd html User s Manual Command Line Version e http www cex3d net inverse documentation dosanddonts index html DOs and DONTs Tutorial This document is also available in PDF format e http www cex3d net inverse documentation manuals usercmd pdf The following sections constitute the user s manual for the command line version of CeX3D Inverse This manual covers both CeX3D Inverse NCU and CeX3D Inverse Pro 1 1 Introduction CeX3D Inverse is a computer program for automatically turning ordinary pho tographs into digital 3D models This is possible for many everyday photos provided that enough photos are taken from suitable angles of the same scene or object The scene or object must be static i e not moving At least two though preferably three or more pictures are necessary for this The pictures must also be sharp i e not too blurry for this to work properly Certain kinds of objects are however not suitable for automatic reconstruc tion Su
6. ch objects include fluffy objects like clouds hair and grass transparent 2012 2014 Hardcore Processing objects and mirrors as well as objects that are too shiny very small or thin ob jects such as wires antennas grids and lattices objects with a smooth surface that are of the same colour all over and has no texture at all If such objects occur in the photos they will likely not be reconstructed very well and if there are too many of such objects it may completely prevent successful 3D recon struction The DOs and DONTs Tutorial is strongly recommended for examples on how to take suitable photographs for 3D reconstruction The quality of the reconstruction will gradually improve over time with new versions of CeX3D Inverse and it will become possible to handle more and more challenging photographs Hence what is not possible to reconstruct today may become possible to reconstruct in a later version of CeX3D Inverse using the same photographs 1 2 General Operation of CeX3D Inverse Performing 3D reconstruction from photos with CeX3D Inverse is done by call ing CeX3D Inverse with a set of pictures given as parameters for input Some options for specifying how the reconstruction is done and how CeX3D Inverse operates can also be specified This is done in a command line shell e g a terminal on Linux systems or a DOS prompt on Windows systems 1 2 1 Examples of Operation As an example reconstructing a 3D model from thre
7. e pictures in files named imageO bmp image1 bmp and image2 bmp can be done by this command c3di imageO bmp image1 bmp image2 bmp The following image formats are supported for input on Linux via the SDL_image library BMP GIF JPEG LBM PCX PNG PNM TGA TIFF WEBP XCF XPM and XV On Windows however only BMP format is cur rently supported we expect this to improve one way or another in coming versions The reconstructed models are generated in the same directory that the com mand is executed from It is possible to specify a hint of the typical radial distortion in the images This was strongly recommended in versions 0 7 0 0 and 0 7 1 0 but has become less important starting from version 0 7 2 0 of CeX3D Inverse This is described in more detail for the command line option radialDistortionHint Cameras typically have a distortion that corresponds to a radial distortion hint of between 0 03 and 0 03 Hence e g 0 02 could be a good hint value Specifying this for the above example gives the command c3di radialDistortionHint 0 02 imageO bmp imagel bmp image2 bmp The radial distortion however depend on which camera is used particularly its lens on how its zoom settings are as well as slightly on focus settings using autofocus makes this somewhat uncontrollable Typically when the camera is zoomed out the distortion is more negative e g 0 02 or lower When zooming in the distortion gets closer to zero or even bec
8. ince this is a command line option and will not have effect until all command line options are correctly understood by CeX3D Inverse Also certain types of error messages that make the 3D reconstruction fail completely most notably if CeX3D Inverse runs out of memory cannot be guaranteed to be written to the specified file This option may be useful when starting the CeX3D Inverse command line program from another program such as a script or a graphical user interface where it is desirable to see output messages This could be used for e g showing output messages in a graphical user interface If this option is not specified no output messages are sent to any file 1 3 5 Option pixelsPerPoint CeX3D Inverse currently generates two different kinds of 3D model files a low resolution model whose file name normally starts with output_secondviewsheet_ and a high resolution model whose file name normally starts with output_volume_ Generating the high resolution model is currently very resource intensive tak ing time and using lots of memory and it may fail The resolution of the high resolution model can be controlled by the option pixelsPerPoint Higher values give a lower resolution and generally requires fewer resources is faster and more likely to succeed Lower values give a higher resolution and requires more resources especially if the input images have a high resolution If your input images have a fairly low resolution e g less
9. l other displayed output is sent to the standard output stream and possibly also to a file if specified by fileOutMessages The progress values are real values in the range 0 0 just started to 1 0 complete Each progress value is written on a separate line This option is useful when starting the CeX3D Inverse command line program from another program such as a script or a graphical user interface where it is desirable to get feedback about the progress This could be used for e g showing a progress bar in a graphical user interface Notice however that if e g the standard error stream is redirected to a file the data is written only rarely and in large chunks on Windows so we recommend using the option fileProgress instead in such cases If this option is specified as false no progress values are sent to the standard error stream
10. omes positive depending on the lens and camera Currently the most frequent point of failure in the reconstruc tion is the radial distortion estimation and for this reason you may want to try the reconstruction with several different values for radialDistortionHint By default the estimated radial distortions are shown during reconstruction see the option showDistortion which may give you an idea of how the actual radial distortion is by comparing the estimated distortion values with the quality of the reconstructed 3D model when you get a good 3D model the estimated radial distortions are likely closer to the truth than when you get a bad model CeX3D Inverse currently generates two different kinds of 3D model files a low resolution model whose file name normally starts with output_secondviewsheet_ and a high resolution model whose file name normally starts with output_volume_ Generating the high resolution model is currently very resource intensive tak ing time and using lots of memory and it may fail The resolution of the high resolution model can be controlled by the option pixelsPerPoint and also depends on the resolution of the input images The default value is 4 and higher values give a lower resolution model To get a model at a lower resolution for the above example try c3di radialDistortionHint 0 02 pixelsPerPoint 8 imageO bmp imagel bmp image2 bmp If your input images have a fairly low resolution e g less
11. onstruction multiple times With CeX3D Inverse Pro any number of formats may be ex ported for the same 3D reconstruction 1 3 3 Option fileProgress The option fileProgress was introduced in version 0 7 2 0 of CeX3D In verse and may be specified to be some file name If this option is specified as e g fileProgress myprogress txt progress values will be sent to the file myprogress txt notice that all other displayed output is sent to the standard output stream and possibly also to a file if specified by fileOutMessages The progress values are real values in the range 0 0 just started to 1 0 com plete Each progress value is written on a separate line This option is useful when starting the CeX3D Inverse command line program from another pro gram such as a script or a graphical user interface where it is desirable to get feedback about the progress This could be used for e g showing a progress bar in a graphical user interface If this option is not specified no progress values are sent to any file 1 3 4 Option fileOut Messages The option fileOutMessages was introduced in version 0 7 2 0 of CeX3D Inverse and may be specified to be some file name If this option is specified as e g fileQutMessages mymessages txt almost all output messages will be sent to the file mymessages txt Output messages relating to errors in the way that command line options are specified will however not be sent to the file s
12. structed 3D model when you get a good 3D model the estimated radial distortions are likely closer to the truth than when you get a bad model 1 3 7 Option randomSeed Some of the algorithms in CeX3D Inverse are based on statistics and random ness If the 3D reconstruction fails it is likely that you have just been unlucky You can change the randomness and try the reconstruction again by specifying a value for the randomSeed option The default value is 2 so specifying a different value than the default e g 3 is done by randomSeed 3 This option is also useful for scientific evaluation of the reconstructions To make such an evaluation multiple reconstructions from the same images and with the same parameters are typically made each reconstruction should then be done with a different value of randomSeed in order to evaluate the average reconstruction quality and the robustness of this quality 1 3 8 Option showDistortion The option showDistortion may be specified to either true or false the default being showDistortion true When set to true the estimated radial distortion for all images will be shown when the camera calibration is complete This is useful for figuring out what a good value for the radial distortion hint may be see the option radialDistortionHint If this option is set to false the estimated radial distortion is not shown 1 3 9 Option showLicense The option showLicense may be specified
13. than 1000x1000 pixels it may instead be desirable to get a higher resolution model c3di radialDistortionHint 0 02 pixelsPerPoint 2 imageO bmp imagel bmp image2 bmp If the 3D reconstruction fails it is likely that you have just been unlucky since some of the algorithms are based on statistics and randomness You can change the randomness and try the reconstruction again by specifying a value for the randomSeed option The default value is 2 so you can try again with a different value c3di radialDistortionHint 0 02 randomSeed 3 imageO bmp imagel bmp image2 bmp The 3D models are by default generated in Wavefront OBJ format RIB format is also supported See the options exportObj and exportRib CeX3D Inverse NCU has the limitation that a reconstructed 3D model may only be exported into one format each time a 3D reconstruction is performed To export into multiple different formats with CeX3D Inverse NCU it is necessary to run the reconstruction multiple times With CeX3D Inverse Pro any number of formats may be exported for the same 3D reconstruction 1 3 Command Line Options The following sections list each of the options for CeX3D Inverse The options are ordered alphabetically according to their names 1 3 1 Option exportObj The option exportObj specifies whether or not to export a reconstructed 3D model in Wavefront OBJ format It may be specified as either true or false i e by writing export0bj true or
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