For one stereo camera, stereo calibration is performed to obtain intrinsic and extrinsic parameters during manufacturing. During the process of usage, intrinsic and extrinsic parameters may be changed, and left image and right image are not aligned any more if rectification is applied. I have some point correspondences between left image and right image.The y coordinates of the correpondences is not same. If I rectify the left and right images, I can find the disparity may be negative which means that the points are behind the camera. I can also triangulate the point correpondences using intrinsic and extrinsic parameters to obtain 3d point coordinates, and the z coordinates of 3d points may be negative.
Is there any way to know whether the disparity is negative without stereo rectification?
Is there any way to know the case the calcuated points is behind the camera without trigulation?
I know the corresponding point doesn't lie on the epipolar line for such cases, however such information can't tell me whether the 3d point of point correspondence is behind the camera. I try to calculate the sign of the distance from the point to the epipolar line but it seems the sign can't tell me such information.