Structured Light Scanning - Distorted Depth

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Hi I am following structured light scanning api through the link below https://docs.opencv.org/3.1.0/d1/d90/...

I have two cameras and one projector and using stereo calibration. Individual and stereo camera calibration error is about 0.2

At the end I get distorted depth of a known flat surface like images - uploaded link below https://ibb.co/fp8jU6

I am getting nearly the same result with or without remapping. https://ibb.co/c3yw96 https://ibb.co/m92pU6

How could I correct these distortion error?