3D reconstruction using stereo camera

1
votes

I try to construct 3D point cloud and measure real sizes or distances of objects using stereo camera. The cameras are stereo calibrated, and I find 3D points using reprojection matrix Q and disparity.

My problem is the calculated sizes are changing depending the distance from cameras. I calculate the distances between two 3D points, it has to be constant, but when object gets closer to the camera, distance increasing.

Am i missing something? The 3D coordinates have to be in camera coordinates, not in pixel coordinates. So it seems inaccurate to me. Any idea?

1
opencvstereo-3d3d-reconstruction
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1 Answers

0
votes

You didn't mention how far apart your cameras are - the baseline. If they are very close together compared with the distance of the point that you are measuring, a slight inaccuracy in your measurement can lead to a big difference in the computed distance.

One way you can check if this is the problem is by testing with only lateral movement of the camera.