ABSTRACT
A análise forense de restos mortais e outros vestígios pode ser complementada pela digitalização tridimensional (3D). A fotogrametria de curta distância, consiste na extração de informações geométricas 3D a partir de imagens fotográficas. O objetivo deste estudo foi comparar cinco sistemas de digitalização (Photoscan®, 123dCatch®, ReCap360®, PPT-GUI® e OpenMVG®+MVS®) quanto à operabilidade e qualidade das malhas 3D geradas a partir de 42 fotografias de um crânio seco, tomadas com um smartphone. Duas escalas métricas ABFO nº2 foram posicionadas rente ao crânio. Após o processamento, as nuvens de pontos 3D resultantes foram convertidas em malhas 3D e/ou texturizadas quando necessário, e redimensionadas em escala 1:1. O número de vértices, faces, fator de escala e uma medida conhecida foram registrados. Recortou-se as regiões que não faziam parte do crânio e novamente o número de faces e vértices foi registrado. Para operabilidade, avaliou-se tempo de processamento, necessidade de conexão à Internet, funcionalidade limitada por versão não paga, texturização automática, entre outros parâmetros. Para qualidade, as malhas também foram avaliadas em seu aspecto visual, em seu aspecto quantitativo de vértices e faces, e diferença estatística das médias das medidas. Embora o uso de duas escalas idênticas tenha gerado artefatos, todos os programas geraram malhas tridimensionais adequadas, com algumas diferenças no resultado final e na operação. Cada ferramenta obteve resultados satisfatórios dentro de suas particularidades. Photoscan® teve operabilidade e resultados bons, porém seu custo pode ser um obstáculo. ReCap360® e 123dCatch® são fáceis de operar, mas dependem de Internet e possuem funcionalidade limitada.
Forensic analysis of skeletal remains and other evidence can be complemented by three-dimensional (3D) scanning. Among the available methods, close-range photogrammetry consists of extracting 3D geometric information from photographic images. The objective of this study was to compare five systems (Photoscan®, 123dCatch®, ReCap360®, PPT-GUI® and OpenMVG®+MVS®) regarding the operability and quality of 3D meshes generated from 42 photographs of a dry skull, taken with a smartphone. Two ABFO n.2 metric scales were placed next to the skull. After processing, the resulting 3D point clouds were converted into 3D meshes and textured when necessary, and resized in 1:1 scale. The number of vertices and faces was recorded. Then, all regions that were not part of the skull itself were cut out and again the number of faces and vertices was recorded. For operability, it was evaluated the processing time, need for Internet connection, functionality limited by unpaid version, automatic texturing, among other parameters. For quality, the meshes were also evaluated in their visual aspect and in their quantitative aspect of vertices and faces, and statistical difference of the mean of the measurements. Although the use of two identical scales has produced artifacts, all programs have generated adequate 3D meshes, with some differences in the result and operation. Each tool reached satisfactory results within its particularities. Photoscan® had good operability and results, but its cost may represent an obstacle. ReCap360® and 123dCatch® are easy to operate, but depend on internet connection and have limited functionality.
Subject(s)
Facial Recognition , Forensic Anthropology , Forensic Dentistry , Imaging, Three-DimensionalABSTRACT
Abstract Introduction Immobilization in a hip spica cast is required in surgical and nonsurgical treatments for children aged three months to four years diagnosed with developmental dysplasia of the hip. Skin complications are associated with the use of the spica cast in 30% of the cases. This research explores the use of photogrammetry and rapid prototyping for the production of a lighter, shower friendly and hygienic hip orthosis that could replace the hip spica cast. Methods Digitalized data of a plastic dool was used for design and fabrication of a customised hip orthosis following four steps: 1) Digitalization of the external anatomical structure by photogrammetry using a smartphone and open source software; 2) Idealization and 3D modeling of the hip orthosis; 3) Rapid prototyping of a low cost orthosis in polymer polylact acid; 4) Evaluation tests. Results Photogrammetry provided a good 3D reconstruction of the dool's hip and legs. The manufacture method to produce the hip orthosis was accurate in fitting the hip orthosis to the contours of the doll. The orthosis could be easily placed on the doll ensuring mechanical strength to immobilize the region of the hip. Conclusion A new approach and the feasibility of both techniques for hip orthosis fabrication were described. It represents an exciting advance for the development of hip orthosis that could be used in orthopedics. To test the effectiveness of this orthosis for developmental dysplasia of the hip treatment in newborns, material and mechanical tests, design optimization and physical tests with patients should be carried.