1. A method for auto-calibration of stereo cameras including a first camera and second camera installable behind the windshield of a host vehicle and orientable to view the environment through the windshield, the method comprising: during motion of the host vehicle, capturing by a processor multiple series of images respectively from the stereo cameras including a first time series of first images from the first camera and a second time series of second images from the second camera; locating a plurality of first image points of at least one of the first images captured from the first camera at a first time; matching at least a portion of the first image points with first image points of at least one other of the first images captured from the first camera at a second time to produce pairs of corresponding first image points respectively in the first images captured at the different times; responsive to the motion of the host vehicle, computing world coordinates from the pairs of corresponding first image points of at least two of the first images captured at the different times from the first camera; matching a plurality of second image points in at least one of the second images captured from the second camera so that the matching second image points correspond to at least a portion of the first image points, using the world coordinates determined from the first camera solving for a plurality of camera parameters of the second camera.