A 3D Impression Acquisition System for Forensic Applications

This paper presents a method with which 3D images of tire track and footprint impressions at crime scenes can be captured with high fidelity, while capturing high resolution 2D color texture images simultaneously. The resulting device is portable, easy to use, is non-destructive of the evidence, and saves time at crime scenes. The same technique can also be used in the laboratory to create 3D depth images of suspect tires or shoe soles. Computer-based pattern matching technology can be used to assist in matching and comparison tasks. The device produces better quality data at a close range obtained in a larger field compared to existing devices. It avoids problems related to occlusions by using two lasers and can digitize long spans of impressions in one scan. The method includes a calibration method which is integrated into the scanning process on site, thus avoiding problems with pre-calibrated configurations becoming stale during transportation and setup.