LIGHT FIELD CAMERA AS TOOL FOR FORENSIC PHOTOGRAMMETRY
Keywords: Lytro, Photogrammetry, Light Field, Point Cloud, Forensics
Abstract. Light field cameras record both the light intensity received by the sensor and the direction in which the light rays are travelling through space. Recording the additional information of the direction of Light rays provides the opportunity to refocus an image after acquisition. Furthermore, a depth image can be created, providing 3D information for each image pixel. Both, focused images and 3D information are relevant for forensic investigations. Basic overview images are often acquired by photographic novices and under difficult conditions, which make refocusing of images a useful feature to enhance information for documentation purposes. Besides focused images, it can also be useful to have 3D data of an incident scene. Capital crime scenes such as homicide are usually documented in 3D using laser scanning. However, not every crime scene can be identified as capital crime scene straight away but only in the course of the investigation, making 3D data acquisition of the discovery situation impossible. If this is the case, light field images taken during the discovery of the scene can provide substantial 3D data. We will present how light field images are refocused and used to perform photogrammetric reconstruction of a scene and compare the generated 3D model to standard photogrammetry and laser scanning data. The results show that refocused light field images used for photogrammetry can improve the photogrammetry result and aid photogrammetric processing.