ToProjectionTransform shift in Y (Principalpoint offset) inverted about vl.opencv

[joreg]

frankly the whole transformation (view/projection) situation between opencv and dx is still a bit of a mess that has to be sorted. this will help us figure things out, so thanks for pointing this out!

[tebjan]

this slide should help, get an understanding of how the basis vectors of the openCV system is represented in our system and then push everything thru the matrix: https://docs.google.com/presentation/d/14rxW-qZ0ZwDIppdc_4uGGYc_Fdm10NbYLMXOKGZ-BCg/edit#slide=id.g549de07e3_125

[tomeic]

It seems to work if inside Perspective, the scale is below the multiply.

[ravazquez]

@tomeic we are tracking down this issue. Can you give us more information as to what camera you are using or why the principal point is flipped in the Y axis please?

[tomeic]

@ravazquez It was some random IDS camera. Apparently the lens was "quite" offcenter and after calibration it showed a significant amount of shift in Y. (Principal point) And when overlaying a 3D scene with the same calibration parameters it didn't fit properly. The principal point was shifted but in the opposite direction. Flipping that offset and all fit well. Only Y seemed flipped.

[ravazquez]

@tomeic thanks for the information, we will test here with IDS cameras and try to replicate.

We have cleaned up the transformation pipeline used in VL.OpenCV quite a bit so if you can have a look here and test again with the latest VL.OpenCV nuget, hopefully things will behave properly now.

[joreg]

closing for lack of feedback.