Terrestrial laser scanning and a degenerated cylinder model to determine gross morphological change of cadavers under conditions of natural decomposition Xiao Zhang a, *, Craig L. Glennie a , Sibyl R. Bucheli b , Natalie K. Lindgren b , Aaron M. Lynne b a Department of Civil & Environmental Engineering, University of Houston, Houston, TX 77204, United States b Department of Biological Sciences, Sam Houston State University, Huntsville, TX 77341, United States A R T I C L E I N F O Article history: Received 27 November 2013 Received in revised form 26 March 2014 Accepted 5 May 2014 Available online 13 May 2014 Keywords: Cadaver Outdoor decomposition Terrestrial laser scanning 3D Modeling Taphonomy Bloat stage of decay A B S T R A C T Decomposition can be a highly variable process with stages that are difficult to quantify. Using high accuracy terrestrial laser scanning a repeated three-dimensional (3D) documentation of volumetric changes of a human body during early decomposition is recorded. To determine temporal volumetric variations as well as 3D distribution of the changed locations in the body over time, this paper introduces the use of multiple degenerated cylinder models to provide a reasonable approximation of body parts against which 3D change can be measured and visualized. An iterative closest point algorithm is used for 3D registration, and a method for determining volumetric change is presented. Comparison of the laser scanning estimates of volumetric change shows good agreement with repeated in-situ measurements of abdomen and limb circumference that were taken diurnally. The 3D visualizations of volumetric changes demonstrate that bloat is a process with a beginning, middle, and end rather than a state of presence or absence. Additionally, the 3D visualizations show conclusively that cadaver bloat is not isolated to the abdominal cavity, but also occurs in the limbs. Detailed quantification of the bloat stage of decay has the potential to alter how the beginning and end of bloat are determined by researchers and can provide further insight into the effects of the ecosystem on decomposition. ã 2014 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Human decomposition is a continuous process whereby features of a cadaver change in a relatively predictable pattern over time relative to temperature [1–3]. As a cadaver decomposes, it passes through several major stages leading from wet decomposition (fresh, bloat) to dry decomposition (decay, mummification, and/or skeletonization.) These stages are artificial yet useful in which they allow for decomposition to be assessed between locations, seasons, and time [2]. Bloat can be an important landmark in gauging progression through decomposition since a fully bloated cadaver is easy to recognize. Bloat is a bacterially mediated process that often results in increased abdominal distention due to a buildup of gasses; the metabolic byproducts of bacterial respiration [1,2,4–6]. Bloat is over when abdominal distention is lost [7], which is often the result of when pressure from these gasses force fluids of decomposition out through natural, artificial, or scavenger-induced openings [7,8]. To assist in criminal investigations, forensic scientists will frequently rely on data from previously published studies to estimate the time since death, or post-mortem interval. This information can also offer insight into abiotic and biotic forces that may have affected the remains after death [1,9]. However, stages of decomposition are not always easily discernable and a cadaver may experience multiple stages of decomposition at once [2,4]. Additionally, bloat is not always experienced to the same degree by every cadaver (personal observations). The use of 3D volumetric change detection shows promise in the field of forensics by providing researchers with a greater insight into the manner of decomposition. Understanding body deformation in terms of volumetric changes may provide researchers with a greater insight into the process of bloat. For example, researchers may be interested in understanding envi- ronmental factors that influence bloat (e.g., the affects of temperature on bacterial communities). Before researchers can * Corresponding author at: University of Houston, 451 Cullen Performance Hall, Houston, TX 77204-5059, United States. Tel.: +1 979 587 9041. E-mail address: xzhang39@uh.edu (X. Zhang). http://dx.doi.org/10.1016/j.forsciint.2014.05.001 0379-0738/ ã 2014 Elsevier Ireland Ltd. All rights reserved. Forensic Science International 241 (2014) 35–45 Contents lists available at ScienceDirect Forensic Science International journal homepage: www.elsevier.com/locat e/f orsciint