REPORT READING & RESEARCH
Contents
1. be done Firstly there is no synchronization mechanism between the four display servers It could be possible that some of the display servers go a little ahead of the others if we want to render a relatively large model Currently because we are using the same graphics cards and same processors in each of the display server the rendering speed doesn t differ too much The user can hardly notice the lag between the servers However it will be more noticeable if using larger model One of the possible ways to handle synchronization problem is to set up a barrier in the rendering loop We can use socket to develop the inner mechanism by ourselves or use existed library like Open MPI However this cannot make a perfect synchronization because the time of outputting pixels onto the screen may still differ To make a perfect synchronization we have to develop hardware synchronization protocol on the graphics card 2 Remotely loading a 3D model So far all of the test 3D models are stored locally in each of the clients which means if you want to use the system properly you have to not only have all of the executable files but also the 3D models This is cumbersome because the user should only need to install the app and download the model from the air Also it will be hard to manage because once you have new models you have to let all of the clients update as well The possible solution is to download the model when the client is conn2. cameras position is made on both the display servers and the secondary clients GOAL OF THE PROJECT The goal of the project is to develop a mesh viewer using the 16 monitors to display in a high resolution way and multiple clients can connect to the system They are free to move the camera locally to have a different view of the currently displayed mesh They are also free to grab the global control over the system to do something globally which will be synchronized to each of the clients This application will be useful for a conference If somebody wants to make a lecture using this system to display some large meshes the audiences can just connect to this system move its camera to look at the mesh freely and locally or just look at the big screen to have a global view So it will be ideal if this application can be ported to tablet or mobile devices because it would be cumbersome to always use laptop MAIN CHALLENGES 1 The protocol of the communication between the master node and the display servers and the protocol between the master node and each of the clients 2 Each of the display servers should be able to pick up one region to display Some matrix calculations are included 3 The changes from the clients should be synchronized to the master node display servers and other clients IV DESIGN OF THE SYSTEM The structure of the system can be decomposed into two parts The first part is the communication betwe
3. Brown University Department of Computer Science Laboratory for Engineering Man Machine System LEMS REPORT OF THE READING amp RESEARCH Supervisor Gabriel Taubin Author Yan Li February 2013 December 2013 INTRODUCTION have worked under the supervision of Prof Gabriel Taubin since February on a project about videowall The project involves the knowledge of computer graphics computer network and synchronization We thought that we could use the videowall in LEMS to develop some innovative applications and started from there The videowall is basically a 4x4 monitor matrix of 16 monitors Since we have 16 monitors it means that we have much more pixels to display Therefore we came up with an idea using the videowall to display something high resolution like very large image or very fine mesh The 4x4 monitors are driven by 4 computers and we treat the 4 computers as display servers In addition to the 4 servers we also have a master node machine which is just in front of the 4 servers We use that master node to control the behavior of the 4 servers So in this structure the master node is like a client Here is a snapshot of the above structure need to firstly develop a robust communication protocol between the master node machine and the 4 display servers Also need to take care of the rendering region for each of the servers because the servers are separate firstly ported a very simple 2D image vie
4. ected to the system The client should have a kind of progressive downloading mechanism because some of the models have super big size and it will be miserable to just keep waiting We can pre compute the models of different resolution and store them in the master node Once a client is connected to the master node it will firstly download a small size model to display on the client s screen After that the client progressively download the full size model from the master node without disturbing the rendering loop When it s done the client just destroys all of the small size models and use the final version to render 3 Other Platform It will be compelling if the client can support other platforms such as cell phone or tablets Since the system is developed using Java it shouldn t be hard to port the code to other platforms as long as they have Java runtime environment The only thing we need to learn is how to develop an app on mobile devices 4 More features More features are expected to add to the system such as model editing and other more complicated operations like modifying the light in the scene More feature means more synchronization between the client and the server which also means more complicated protocol Vil POTENTIAL BUGS One minor bug is about the normal Sometimes the normal status Per vertex or Per face is not synchronized to the other clients and master node haven t figured out the reason for t
5. en the master node and display servers The second part is the structure between the master node and multiple secondary clients use Java s sockets to implement the network communication 1 Structure of the master node and the display servers The structure is like the following diagram Screens Screens Screens Screens Render loop Render loop Render loop Render loop Server1 Server2 Server3 Server4 YT mmmn Bh Sockets for servers Master Node Here the network protocol is simple L Transformation of the all the cameras 2D float array Transferred whenever the transformation of any camera is changed Frustum information of the camera 2D float array Transferred whenever the frustum of any camera is changed Other settings The gap size of the video wall topology position of each screen etc Transferred when the connection is built Mesh name String Transferred whenever a new model is loaded Normal settings String Transferred whenever the normal setting is changed The ids of the used threads Integer array Transferred whenever a new client is connected Number of max clients Integer Transferred when the connection is built Structure of master node and secondary clients Sockets for clients aster Node Client 1 Client2 Client3 The network protocol is exactly the same with the protocol between the
6. his VIIIL RESULTS Snapshots of the system Mesh Viewer Mesh Viewer with multiple clients
7. ompile_windows bat on Windows or running compile bash on Mac To run it on the laptop in a test mode either click run_local_ windows_server1 bat run_local_ windows_server2 bat run_local_ windows_server3 bat and run_local_windows_server4 bat on Windows or run run_local_ machome bash on Mac If you want more details or complicated start open the source code OGLVW3DServer java to see the argument lists 2 Launch the master node and connect to display servers have created a shortcut on the master node machine in LEMS so just click run_videowall_ client bat on the desktop of that machine then the program will start If you want to test it on your laptop locally firstly copy the project OGL3DVWClient from the repository and compile it by clicking compile _windows bat on Windows or running compile bash on Mac If you want this program to connect to the video wall click run_videowall bat on windows or run run_videowall bash on Mac If you want this program to connect your test servers on your laptop click run_local bat on windows or run run_local bash on Mac After the program has launched you will see the user interface which looks like the following r SI IfsViewer IFS VIEWER DATA FILE UI components Open start the connection to the display servers Close close the connection Shutdown shut do
8. servers and master node except that it also includes the information of whether the global control is grabbed by one of the clients USER MANUAL All of the system display servers and master node is located at LEMS at BARUS amp HOLLEY building The project is in the directory VideoWalls 3DIFSViewer finalversion of the repository The display servers have already been configured so probably you don t need to do anything trivial on it Since the display servers are separated use synergy to simplify the mouse and keyboard control over the display servers Synergy will be started once you boot the system and enter the login page recommend you boot the master node firstly and after you have logged in the master node boot the 4 display servers They will be connected to the master node automatically You can use the mouse and the keyboard of master node to control the display servers All of the source code is located in the repository Before you start firstly make sure that JOGL is installed in your machine and the path is included in the environment variable CLASSPATH 1 Launch the display servers have created a shortcut for each of the server on the desktop Just click run_videowall bat and it will launch You have to do the same thing for each of the 4 servers If you want to test it on your laptop copy the project OGL3DVWServer from the repository and then compile it by clicking c
9. wer into my system used Java programming language and JOGL to handle the rendering part Basically each of the servers has a local copy of the image and so is the master node When the connection is built each the 4 servers loads image locally but each of them picks a different area to render JOGL has the property of clipping the unnecessary rendering region so that part is done in hardware with high efficiency The program running on the master node is just used for manipulating the whole application globally then used this idea and developed a 3D mesh viewer using my system It was more complicated because in a 3D scene a camera is used to capture the image However the idea was just similar and just needed apply the idea on the near plane of the camera s frustum Finally developed a secondary client which can connect to the master node Here the master node is more like a global server There could be many secondary clients connecting to the master node Once a secondary client connects to the master node a new camera view will be assigned to it and it can move the camera freely to have a different view other than the global view The client can also grab the global camera to manipulate the global view Once one client grabs the global control all of the other clients will be locked out The information of all of the cameras will by synchronized to each of the clients and the master node In addition a visualization of the
10. wn the servers if connected Grid show the frame of the display servers that is marked as red 3 Launch the client Firstly copy the project OGLVW3DSubClient from the repository and compile it by clicking compile bat on Windows or running compile bash on Mac If you want this client to connect to the master node machine in LEMS click run_videowall_ client bat on Windows or run run_videowall_ client bash on Mac If you want the client to connect to the local master node click run_local_client bat on Windows or run run_videowall_client bash on Mac After you have successfully launched the program you will see the user interface that looks like this Video Wall 3D Viewe UI Components Open Open the connection to the master node Close Close the connection to the master node SHUT Shut down the connection to the master node GRID Show the frame of display servers SHOW CAM Visualize other cameras locally LOCK Grab the lock over the global control of camera LOAD Load a mesh Only available if you have grabbed the global control NORM PER FACE Change the norm to be per face Only available if you have grabbed the global control NORM PER VERT Change the norm to be per vertex Only available if you have grabbed the global control VI FUTURE WORKS 1 Synchronization mechanism between display servers There are a lot of future works and optimization that can
Download Pdf Manuals
Related Search