Custom principal point

[syncle]

ConvertFromPinholeCameraParameters function in Open3D/src/Visualization/Visualizer/ViewControl.cpp is designed for deterministic pinhole camera model: its principal point should be central position of an image domain.

For example, ViewGeometry terminates if below condition does not meet:

intrinsic.intrinsic_matrix_(0, 2) != (double)window_width_ / 2.0 - 0.5 ||
intrinsic.intrinsic_matrix_(1, 2) != (double)window_height_ / 2.0 - 0.5)

Can we extend current OpenGL interface to allow principle point of non-centered position?

[qianyizh]

No. Because this is OpenGL behavior.
If you render using OpenGL, the captured image has principle point (w/2-0.5, h/2-0.5).

We need to add different rendering shaders if we are to remove this sanity check.