I want to render the normals of a scene in Blender, and I'm doing this with the the 'normals' matcap texture. It seems to be mostly correct. At least in some simple test cases, the pixel intensities matched my calculated values.
However, I animated a 360-degree camera spin, and at one point many of the pixels turn grey. This is super weird to me since in the frame before and after (where the camera angle is slightly different), the colors are strongly red or blue. Is this a bug or is this expected behavior?
Here are the frames before and after the greying.