LIGHT FIELD CAMERA AS TOOL FOR FORENSIC PHOTOGRAMMETRY

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.

[1]  Edward H. Adelson,et al.  Single Lens Stereo with a Plenoptic Camera , 1992, IEEE Trans. Pattern Anal. Mach. Intell..

[2]  Michael J. Thali,et al.  Crime scene reconstruction using 3-D scanning and medical imaging technologies , 2010 .

[3]  P. Hanrahan,et al.  Light Field Photography with a Hand-held Plenoptic Camera , 2005 .

[4]  Zhan Yu,et al.  Line Assisted Light Field Triangulation and Stereo Matching , 2013, 2013 IEEE International Conference on Computer Vision.

[5]  Sven Wanner,et al.  Variational Light Field Analysis for Disparity Estimation and Super-Resolution , 2014, IEEE Transactions on Pattern Analysis and Machine Intelligence.

[6]  Michael J Thali,et al.  3D documentation of footwear impressions and tyre tracks in snow with high resolution optical surface scanning. , 2007, Forensic science international.

[7]  Michael J Thali,et al.  Accident or homicide--virtual crime scene reconstruction using 3D methods. , 2013, Forensic science international.

[8]  Daniele D. Giusto,et al.  3D Point Cloud Reconstruction from Single Plenoptic Image , 2016 .

[9]  Robert Breitbeck,et al.  Forensic 3D surface documentation at the Institute of Forensic Medicine in Zurich – Workflow and communication pipeline , 2016 .

[10]  Michael J. Thali,et al.  Non-Contact Documentation of Physical Characteristics of Ecstasy Tablets, Hemp Coins, and Imprint Punches by using 3D Optical Surface Scanning , 2008 .

[11]  M. Thali,et al.  Optical 3D surface digitizing in forensic medicine: 3D documentation of skin and bone injuries. , 2003, Forensic science international.

[12]  Alexei A. Efros,et al.  Occlusion-Aware Depth Estimation Using Light-Field Cameras , 2015, 2015 IEEE International Conference on Computer Vision (ICCV).

[13]  Michael J Thali,et al.  The forensic holodeck: an immersive display for forensic crime scene reconstructions , 2014, Forensic Science, Medicine, and Pathology.

[14]  Lennart Wietzke,et al.  Single lens 3D-camera with extended depth-of-field , 2012, Electronic Imaging.

[15]  In-So Kweon,et al.  Accurate depth map estimation from a lenslet light field camera , 2015, 2015 IEEE Conference on Computer Vision and Pattern Recognition (CVPR).

[16]  Christopher D Duncan.  Advanced Crime Scene Photography , 2010 .

[17]  Edward M. Robinson,et al.  Crime Scene Photography , 2007 .

[18]  Annett Wechsler.  The Practical Methodology Of Forensic Photography , 2016 .

[19]  Uwe Stilla,et al.  NARROW FIELD-OF-VIEW VISUAL ODOMETRY BASED ON A FOCUSED PLENOPTIC CAMERA , 2015 .

[20]  Daniele D. Giusto,et al.  An analysis of 3D point cloud reconstruction from light field images , 2016, 2016 Sixth International Conference on Image Processing Theory, Tools and Applications (IPTA).

[21]  M. Landy,et al.  The Plenoptic Function and the Elements of Early Vision , 1991 .

[22]  Nick Marsh.  Forensic Photography: A Practitioner's Guide , 2014 .

[23]  Michael J Thali,et al.  Application of 3D documentation and geometric reconstruction methods in traffic accident analysis: with high resolution surface scanning, radiological MSCT/MRI scanning and real data based animation. , 2007, Forensic science international.