I am using matrix rotations to rotate a world sphere in front of a static camera.

I want to know the latitude and longitude of the point directly beneath the camera.

I'm appending rotation on the Z axis to 'turn' left and right and appending rotations on the X axis to move forward/backward.

The matrix3D is decomposed to give me the x,y and z rotations - but am having difficult applying this to calculate the latitude/longitude. What do I do now?

Any help is gratefully received.