Geometrical methods for accurate forensic videogrammetry. Part II. Reducing complexity of Cartesian scene measurements via epipolar registration
Lenny I. Rudin, Pascal Monasse, Ping Yu · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2005
We present the technical steps involved in a new method of photogrammetry, requiring much fewer measurements in the observed scene, no availability of the original camera’s calibration, and no prior knowledge of its position and orientation. The practical setup involves minimal humans measuring intervention. This largely automatic configuration permits to get accurate lengths, angles, and areas measurements in the original scene without prospecting the 3-D Cartesian coordinates for known points. The crucial observation is that the two snapshots, even if not simultaneous and from different cameras, provide a stereo system. Therefore the correspondence of 8 points in the views gives the epipolar geometry of the stereo setup, and as one of the camera is calibrated, the calibration can be “transferred” to the other camera through the epipolar matrix. This transfer yields a calibration of the original camera (internal parameters and position in the scene) even if it is not available anymore, its settings have changed, its orientation is different or it was moved. Thus we replace the technically difficult, time-consuming, and potentially error prone data collection by the epipolar registration and some rudimentary scene measurements. This new technique can also be applied to the task of photo-comparison.