Question about initUndistortRectifyMap & remap function

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Hi,
I study opencv finsheye calibration document, and using initUndistortRectifyMap and remap function to get undistortion result. Then there ara some question:

1). The output of initUndistortRectifyMap map1 and map2 are 2 channels and 1 channel respectively. According to document about remap, I know the reason why map1 is 2 channels, but what is map2 meaning?
2). I use remap funcion, and try to let map2 be None, but get the wrong result, the pixel values in result are all (0, 1, 0). Why?

image
image963Ă—280 15.3 KB

Thanks

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Welcome!

See convertMaps for details

1 Like
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Hi crackwitz,

Thanks for your prompt reply.
There are some questions I still don’t understand:

  1. According to convertMaps page I know that the first output array contains the rounded coordinates. But I still don’t understand why the second output array contains indices in the interpolation tables ?

  2. I understand interpolation, but what is interpolation table doning? In my situation, map2 is a output array with size w*h, and value between 0~1024.

  3. In remap function, When map1 and map2 are both 1-channel, representing map_x and map_y, I can clearly understand what the remap function is doing.
    However, when map1 and map2 are 2-channel and 1-channel respectively, I am not sure what the remap function does.

Thanks