Hi Idan,
When you do uncalibrated rectification, the rectified views do not always end up parallel, but may be verged a little. That means the disparity may actually be negative for objects that are far away. I think this is what happened to the car at the end of the parking lot. In a case like this, if you compute the disparity map, you should subtract the minimum disparity value from the map. This will shift the range, to make the minimum disparity 0.
