# Anthropological Comparative Analysis of CCTV Footage in a 3D Virtual Environment
## 1 Introduction  
An image is a particularly valuable data source in medico-legal and forensic assessments [1]. Analysis of photographs and video footage from closed-circuit television (CCTV) cameras can provide a lot of key information about the sequence of events during criminal incidents [2; 3; 4]. One of the primary analyses mentioned above is to assess whether a graphically recorded object corresponds to the object examined in reality. The examined case showed a real need for verification of the object in the footage. The object in question was the figure of the perpetrator, compared to the actual comparative material for the purposes of personal identification. The comparative material was the body figure of the suspect detained in the case. The incident was an armed robey at commercial premises. Two CCTV cameras present at the crime scene simultaneously recorded the footage of the incident, showing the figure of the masked perpetrator. In the course of the conducted procedural actions, the suspect was detained and taken into custody. The image of the body figure of the suspect was captured during photo shoots at the place of incarceration. The aim of the analysis was to demonstrate or exclude a correlation between the spatial geometry of the figure of the perpetrator (CCTV video footage) and the figure of the suspect (image recorded during photo shoots at the place of detention). The main problem and challenge of this type of analysis is to determine the physical dimensions of the examined object whose image was recorded. It is especially complicatedwhen the examined object is in motion and, additionally, its geometry changes during the motion. One such object is the human body, whose shape and size are an indispensable subject of comparative studies [5]. The main parameters for comparing the object with its recorded image are color, geometry, and dimensions. The problem of object analysis in video footage was considered in several aspects. The first was the perspective distortion, which makes it impossible to read the actual measurements in the image. In addition, the footage from CCTV cameras often shows lens distortion characteristic of lenses with short focal lengths, often used in CCTV systems to provide a wider field of view. The lines that are actually parallel become curves in the image of a short focal length camera. This significantly hinders the use of manual descriptive geometry to reconstruct the dimensions of objects in the image. Another factor is scale reconstruction, i.e., determination of the actual dimensions of the entire scene visible in the video footage or selected objects within that scene. The method of scale reconstruction can be determined using many factors, ranging from the nature of the technical quality of the source material itself (e.g., resolution, glitches, and number of frames) to the specificity of space and objects shown in it (e.g., orthogonal, polygonal, oval, multi-colored, and monochromatic) to its available documentation (e.g., kinetics of the recorder and the number of different shots of the same space). Another aspect is the measurement of the object visible in the footage or photo. The human figure is a particularly complex object to measure accurately and reliably [6]. The human body is a morphic form; the lack of clear edges or vertices makes measurements difficult, especially when the body is foreshortened, even without lens distortions. The problem of measurement is related to both the difficulty of applying a ruler to the actual material (i.e., a person) and determining the extreme parts of the geometry in the image (Figure 1). Figure 1: Body measurement issues in perspective (**A**,**C**) versus isometric view (**B**,**D**). The “?” points shows distance that can not be measured (because of perspective view focal distortion). The “X” and “Y” points shows distance that can be measured (because ortographic view is geometrically undistorted).