Accident Reconstruction via Digital Close-range Photogrammetry

With the ever wider adoption of spatial information analysis, there has been an increasing awareness of the importance of 3D data acquisition systems to support traffic accident reconstruction and forensic analysis. In an application such as accident reconstruction, GIS and CAD systems have limited utility without the underlying data. Digital close-range photogrammetry displays many attributes which make it a well suited technology for the provision of the necessary 3D measurement data. The application of photogrammetry to accident reconstruction is not without difficulties, however. These include accommodation of the generally very poor, near-planar network geometries encountered and the need for maximum ease of use, from which follows the requirement for highly automated processing and fully automatic camera calibration. This paper concentrates upon developments undertaken to enhance the applicability of close-range photogrammetry and consumer-grade digital cameras to accident reconstruction and forensic measurement. The developments comprise a new approach for robust on-line image orientation and a method for automatic camera calibration which employs colour coded targets. These are highlighted through reference to the iWitness system for close-range photogrammetry.