Multi-Projector Based Display Code ---- FAQ

Frequently Asked Question

1. How do I know that my camera has a proper lens?
   Answer: If you can see exactly the whole display area while connecting the camera to the master PC, then it's a proper lens. In fact, what we mean proper here is that the lens comes with suitable focal length and field of view (FOV). In our configuration, when putting the camera behind the projectors about 3 meters away from the display wall, we use a 8mm lens. You can find plenty of information from the web about how to caculate the focal length you need in your working scenario and how to choose camera lens.
2. How do I know that my camera is OpenCV-compatible?
   Answer: Please download the test program from here. You can run it on the PC with camera connnected, if you see a camera viewer smoothly, then the camera is OpenCV-compatible. Otherwise, the camera is not OpenCV-compatible and can not be used in this project.
3. I met the following error: "xx features detected! Please check camera image" ?
   Answer: Please open the debug image located at the same directory. The possible reason might be: unexpected obstacle objects seens by the camera; ambient light too bright or too dark that white blobs and black background can not be distinguished.
4. What if the program crashed during running ?
   Answer: Please close all the running programs (include other render server programs and/or control client programs) and re-run the system according to the step-by-step guide. If the same problem still exists, please check the error message and look into the source code yourself.
5. What if the render server have no response ?
   Answer: The most possible reason is that the network traffic is banned by the firewall. All the programs use UDP socket to communicate with each other and might not be successful if your firewall is turned on. Please turn off the firewall or allow the traffic by these programs in the firewall configuration. Another reason might be wrong configuration file is given in the control client, please check the ip address, port etc in the configuration file.
6. Is there any difference between the calbration result generated from Mulit-Prjector Multi-PC configuration and Multi-Projector Single-PC configuration?
   Answer: As long as the physical projector arrangement is the same (for example, both are for 2x2 or 2x1) the calibration result is exactly the same.
7. What if I found bugs in the codes?
   Answer: We would be very thankful if you could help us improving the codes by email a detailed description of the bug to the following address: brown at comp.nus.edu.sg .
8. What if I still have questions regarding the codes?
   Answer: Please email to brown at comp.nus.edu.sg.