OpenCV Stereo Calibration of IR-Cameras

asked 2015-05-20 15:17:42 -0500

I have 2 webcams with removed IR blocking filters and applied visible light blocking filters. Thus, both cameras can only see IR light. So I can not calibrate the stereo cameras by oberserving points on a chessboard (because I don't see the chessboard). Instead of this I had the idea to use some amount of IR-LEDs as a tracking pattern. I could attach the LEDs on some chessboard, for instance. AFAIK, the OpenCV stereoCalibrate function awaits the objectPoints, as well as the imagePoints1 and imagePoints2 and will return both camera matrices, distortion coeffs as well as the fundamental matrix.

How many points in my images do I need to detect in order to get the function running appropriate? For the fundamental matrix I know the eight-point algorithm. So, are 8 points enough? The problem is, I don't want to use a huge amount of IR-LEDs as a tracking pattern. Are there some better ways to do so?

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I don't understand why you don't see chessboard. CCD.A webcam can see light between 0.4 to 1.2 micrometer. When you remove filter you can see near infrared and visible light. So you have much energy on your sensor and I think now you have a problem with contrast and your sensor is saturated. If you have a sensor for thermic infrared you cannot use a classic chessboard to calibrate because chessboard temperatures are similar and hence there is no contrast

LBerger gravatar imageLBerger ( 2015-05-21 01:41:36 -0500 )edit

Because I applied a visible light filter. The webcams are only able to see near infrared light. Here, the webcam is observing one IR-LED

SeA_Sharp gravatar imageSeA_Sharp ( 2015-05-21 03:17:45 -0500 )edit

I still do not understand.You can see here quantum efficiency. If you use a chessboard with day light you must see something. And I don't think that intrensic camera parameter change if you change wavelight length.except if your filter is lens and not a window. May be your visible visible filter is too large. Have you got wavelength response of your visible filter?

LBerger gravatar imageLBerger ( 2015-05-21 04:55:19 -0500 )edit