I got 3D point cloud by using stereo camera and sample stereo_calib.cpp and stereo_match.cpp. And, when viewed in the point cloud gnuplot, scale is very small compared with the reality.
I used 9x6 checkerboard of square size 3.45cm. Of course, squareSize of source code, I've assigned a 3.45. As a result, RMS error=0.221828 and reprojection error=0.261209, and rectified images was good. Then, place the object to the location of the shooting distance of 100cm from the stereo camera, I got a 3D point cloud using stereo SGBM. However, average Z value of that object was 6.
Why not?