Reconstrução 3D de Objetos com Kinect e Câmera Digital

Objetos com áreas superficiais complexas e detalhes de reprodução manual impraticável em software de Computer Aided Design (CAD) são os principais alvos dos processos de escaneamento e reconstrução 3D. Neste trabalho, foi concebido um método para a reconstrução e geração de modelos 3D. Informações de geometria e cor de objetos reais foram respectivamente capturadas por um sensor de profundidade Microsoft Kinect 360 e uma câmera digital de alta qualidade, objetivando um processo de baixo custo. Apresenta a metodologia, equipamentos, processos e resultados iniciais da reconstrução 3D de objetos culturais importantes do Museu de Arqueologia e Etnologia (MAE) da UFBA

Low-cost 3D reconstruction of cultural heritage artifacts

3D reconstruction methods can be used to obtain digital models by capturing the shape and appearance of real objects. Due to both scientific and technological advances, low-cost 3D reconstruction is now widely used to reconstruct objects of reasonable geometric complexity using cheap acquisition hardware; however, it is unclear whether or not these devices produce suitable results to preserve cultural heritage artifacts. First, this paper goes over the general concept of 3D reconstruction and the main differences between low-cost and general-purpose 3D reconstruction pipelines, these differences are illustrated using a prototypical low-cost pipeline that has been used to reconstruct heritage artifacts. Then, we present the results of a survey conducted in order to investigate how existing low-cost 3D reconstruction approaches attempted to improve the results of their reconstructions, with an emphasis on the realistic rendering techniques they have used. Throughout the survey process, a categorization for low-cost 3D methodologies was proposed based on the scanning apparatus used by the approaches and other similarities between them. Finally, based on the surveyed studies and the results obtained with the prototypical pipeline, we conclude that it is possible to preserve heritage artifacts using low-cost approaches, granted that modern realism techniques are used to improve the appearance of the models

Low Cost Real Time 3D Reconstruction of Large Scale Excavation Sites

The 3D reconstruction of archeological sites is still an expensive and time-consuming task. In this article, we present a novel interactive, low-cost approach to 3D reconstruction and compare it to a standard photogrammetry pipeline based on high-resolution photographs. Our novel real-time reconstruction pipeline is based on a low-cost, consumer-level hand-held RGB-D sensor. While scanning, the user sees a live view of the current reconstruction, allowing the user to intervene immediately and adapt the sensor path to the current scanning result. After a raw reconstruction has been acquired, the digital model is interactively warped to fit a geo-referenced map using a handle-based deformation paradigm. Even large sites can be scanned within a few minutes, and no costly postprocessing is required. The quality of the acquired digitized raw 3D models is evaluated by comparing them to actual imagery, a geo-referenced map of the excavation site, and a photogrammetry-based reconstruction. We made extensive tests under real-world conditions on an archeological excavation in Metropolis, Ionia, Turkey. We found that the reconstruction quality of our approach is comparable to that of photogrammetry. Yet, both approaches have advantages and shortcomings in specific setups, which we analyze and discuss

Reconstruçao 3D de acervos culturais usando câmeras RGB-D : solução de compromisso entre precisão e tempo aplicada ao projeto Aleijadinho Digital

Orientador : Olga Regina Pereira BellonCoorientador : Luciano SilvaTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Informática. Defesa: Curitiba, 29/04/2016Inclui referências : f. 67-78Área de concentração : Ciência da computaçãoResumo: Neste trabalho é proposto a utilização de câmeras RGB-D dentro do contexto de digitalização 3D de acervos culturais. O grupo de pesquisa no qual este trabalho foi desenvolvido está atuando no projeto Aleijadinho Digital. Este projeto consiste da digitalização do acervo deixado pelo artista barroco Aleijadinho. Uma das contribuições desta tese está na apresentação de um estudo comparativo sobre os projetos mais relevantes da área da preservação digital. As diversas tecnologias de geração 3D destes e outros projetos de preservação cultural também são discutidas e classificadas. Os scanners tradicionalmente utilizados nestes trabalhos possuem alta precisão, chegando na casa dos micrômetros. No entanto podem custar até centenas de milhares de dólares, necessitam de tripés, fonte própria de energia, treinamento para calibrar e operar o equipamento, espaço físico amplo e a aquisição pode durar alguns minutos para uma única captura. Enquanto os sensores RGB-D apesar da menor precisão realizam até 60 capturas por segundo, são simples de serem operados, necessitam apenas da conexão com um notebook e em geral custam até 100 dólares. Diversos trabalhos recentes apresentaram métodos que exploram o potencial destes sensores. No entanto, estas abordagens com frequência apresentam deformações quando aplicadas em reconstruções 3D completas, 360 graus, para diversos objetos. Neste trabalho é proposto uma metodologia completa de reconstrução 3D baseada em câmeras RGB-D. E para atenuar o efeito da deformação é apresentado um método de alinhamento baseado em pares que expande o grafo de conectividade. Isto é feito através de um método original para detecção automática de novos pares de malhas 3D com região de sobreposição. Esta medida permite que eventuais erros de alinhamento sejam distribuídos de forma mais homogênea entre um maior número de pares de alinhamento. Esta técnica de alinhamento é importante pois o acúmulo de erro é intensificado pela grande quantidade de imagens geradas por câmeras RGBD. Os experimentos foram realizados utilizando os dados de 30 obras do projeto Aleijadinho Digital, realizado em parceria com a UNESCO. Com o auxílio de modelos criados com um sensor 3D de precisão submilimétrica específico para tarefa de reconstrução 3D, experimentos comparativos foram realizados contra outros métodos estado da arte. Os resultados apresentados foram favoráveis ao método proposto no que diz respeito a precisão geométrica. Palavras-chave: kinect, alinhamento, reconstrução 3D, acervos culturais.Abstract: This work proposes a 3D reconstruction method using RGB-D cameras within the context of 3D digital preservation of cultural heritage. Our research group is involved in Digital Aleijadinho project, which consists of the digitization of the artworks from this baroque artist. We present a comparative study of the most influential projects of the digital preservation area, their contributions and 3D generation technologies. Scanners traditionally used in these projects can achieve micrometer precision. However they also can cost up to hundreds of thousands of dollars, require tripods, own source of energy, training to calibrate and operate the equipment, ample space and the acquisition may take several minutes for a single capture. While the RGB-D sensors despite the lower precision they achieve up to 60 fps, they are easy to operate, requiring only the connection to a notebook and generally cost up to $100. Several recent studies presented methods that exploit the potential of these sensors. However, these approaches often exhibit errors when applied to full 3D reconstruction of di_erent objects, known as the loop closure problem. This work proposes a complete methodology of 3D reconstruction based on RGB-D cameras.And to mitigate the loop closure e_ect we present an pairwise alignment method that expands the graph connectivity.This is done through a new method that expands connections in a pairwise alignment system by automatically discovering new pairs of meshes with overlapping region. Then the alignment error is distributed more evenly over the aligned pairs avoiding the loop closure of full 3D reconstructions. Our alignment approach is necessary because the error accumulation is intensified by the large amount of data generated by RGB-D cameras. The experiments were performed using the data of 30 artworks of Digital Aleijadinho project, conducted in partnership with UNESCO. Our experiments show detailed 3D models and favorably compare with state-of-the-art methods found in literature. Keywords: kinect, alignment, 3D reconstruction, cultural heritage

Documentation du patrimoine de l'assemblage de fossiles du site de Kromdraai contenant des hominines (Afrique du Sud) : techniques de numérisation 3D, analyse spatiale quantitative et estimation de volume

Cette thèse explore l'utilisation de données multi-échelles pour modéliser une représentation tridimensionnelle (3D) et générer un registre numérique complet d'un assemblage de fossiles contenant des hominines à partir de l'unité lithostratigraphique P à Kromdraai situé dans le " berceau de l'humanité " classé au patrimoine mondial par l'UNESCO (Province de Gauteng, Afrique du Sud). Les objectifs principaux de cette recherche sont d'illustrer en 3D la progression temporelle et spatiale des fouilles de Kromdraai sur la période 2014-2018, d'analyse la distribution spatiale des vestiges d'homininés et de faune, comme des outils, et finalement, de fournir une documentation sur le patrimoine archéologique de Kromdraai. Nous avons réalisé une analyse multi-scalaire du site, avec l'application de méthodes de photogrammétrie terrestre et aérienne. Conformément aux principes et directives de la gestion du patrimoine archéologique mandatés par les agences internationales telles que l'UNESCO, nous présentons également un protocole de documentation du patrimoine. Nous avons utilisé des technologies de capture de données 3D pour numériser le site de Kromdraai et ses éléments archéologiques découverts entre 2014 et 2018 lors des fouilles. Cette recherche présente une technique originale développée pour la visualisation et la quantification des sédiments volumiques prélevés sur le site à chaque période de fouille par chaque fouilleur. Les estimations de volume calculées à l'aide de la photogrammétrie 3D fournissent un contexte temporel et spatial des sédiments prélevés lors des fouilles successives, et permettent un repositionnement virtuel et plus précis des vestiges découverts ex situ. De plus, nous avons mis en place une modélisation des métadonnées pour démontrer l'utilisation d'un système de gestion de base de données 4D pour la fusion, l'organisation et la diffusion de l'ensemble des données du site de Kromdraai et le partage de la propriété intellectuelle. Nous introduisons également l'une des premières approches statistiques de la modélisation spatiale 3D dans un site Plio-Pléistocène porteurs d'hominines en en Afrique du Sud. En mettant en œuvre des méthodes classiques de tests statistiques telles le partitionnement de données spatiales 3D, nous avons étudié les modèles de l'assemblage de fossiles dans l'unité P, ainsi qu'un échantillon de 810 spécimens catalogués entre 2014 et 2018. Le regroupement de bovidés, de carnivores, d'homininés et de primates non humains a révélé un modèle de distribution spatiale non uniforme des fossiles in situ. Cette recherche présente des méthodes précieuses qui peuvent être appliquées à d'autres sites fossiles contenant des hominines dans le berceau de l'humanité. Ces méthodes peuvent être appliquées pour documenter une fouille archéologique et reconstruire un site en 3D, ainsi que pour documenter des informations patrimoniales. Nos résultats permettent d'améliorer l'interprétation des assemblages fossiles à l'aide d'analyses basées sur des modèles 3D au sein d'un assemblage contenant des hominines.This thesis uses multi-scalar data to create a three-dimensional (3D) representation and, to generate a complete digital record of the early hominin-bearing fossil assemblage from the lithostratigraphic Unit P at Kromdraai in the Cradle of Humankind World Heritage Site (Gauteng Province, South Africa). The main purposes of this research were to illustrate in 3D the temporal and spatial progression of the excavations at Kromdraai since 2014, to investigate the spatial distribution of the hominin, faunal assemblages and artefacts, and ultimately, to provide an archive documenting the archaeological heritage of Kromdraai. We provided a multi-scalar analysis of various aspects of the study site, with the application of methods such as multi-image land and aerial photogrammetry. In alignment with the principles and guidelines for the management of archaeological heritage mandated by international agencies such as UNESCO, we also present a protocol for heritage documentation. We used 3D data capture technologies to record the Kromdraai site and the archaeological evidence discovered between 2014 and 2018 from its main excavation. This research presents an original technique developed for the quantification and visualization of the volume sediments removed from the site during each excavation period. Volume estimations computed using 3D photogrammetry and digitization, provided a temporal and spatial context to the volume and location of material removed by each excavator and, a more precise and virtual repositioning of the fossil material discovered ex situ. Furthermore, we implemented metadata modelling to demonstrate the use of 4D relational database management systems for the fusion, organisation and dissemination of the Kromdraai site dataset and the sharing of intellectual property. We also introduce one of the first statistical approaches of 3D spatial patterning in Plio-Pleistocene early hominin-bearing assemblages in South Africa. Implementing classic statistical testing methods such as k-means and Density-Based Spatial Clustering and Application with Noise (DBSCAN) cluster computation in 3D, we investigated the spatial patterns of the fossil assemblage within Unit P, a sample of 810 individually catalogued specimens recovered between 2014 and 2018. The clustering of bovids, carnivores, hominins, and non-human primates revealed a non-uniform spatial distribution pattern of fossils in-situ. This research presents valuable methods that can be applied at other hominin-bearing fossil sites within the Cradle of Humankind to document an archaeological excavation and to reconstruct of the site in 3D, to document heritage information, and to enhance the interpretation of the fossil assemblages using evidence-based assessment of spatial patterns within a hominin-bearing assemblage