Can disparity range from negative to positive values for parallel cameras? In my stereo-rectified camera pair (not physical, but two positions of the same camera), when I project some 3D points in both images to find a rough disparity range, I often get a range that goes from negative to positive (e.g. -11, 24). I have no problem with ranges like (-22, -10) or (10, 15).

Is that kind of range even possible? When I do stereo matching how should I treat negative values? And what about the depth calculated from that disparity that can have negative values (and possibly areas with lowest cost at 0 disparity)?
It was the way I was setting principal points during rectification, to center the images back for the warping. If I have same principal points in both cameras I only get positive disparities, as expected. If cameras are parallel, it is not possible to have both negative and positive disparities. That only happens with converging stereo cameras (negative disparities for objects in front of point of convergence and positive for objects in the back).