This thesis describes a method to create local maps from an omni-directional vision system (ODVS) mounted on a mobile robot. Range finding is performed by a structure-from-motion method, which recovers the three-dimensional position of objects in the environment from omni-directional images. This leads to map-making, which is accomplished using certainty grids to fuse information from multiple readings into a two-dimensional world model. The system is demonstrated both on noise-free data from a custom-built simulator and on real data from an omni-directional vision system on-board a mobile robot. Finally, to account for the particular error characteristics of a real omni-directional vision sensor, a new sensor model for the certainty grid framework is also created and compared to the traditional sonar sensor model.

The determination of the 3D motion of a camera and the 3D structure of the scene in which the camera is moving, known as the Structure from Motion (SFM) problem, is a central problem in computer vision. Specifically, the recursive (online) estimation is of major interest for robotics applications such as navigation and mapping. Many problems still hinder the deployment of SFM in real-life applications namely, (1) the robustness to noise, outliers and ambiguous motions, (2) the numerical tractability with a large number of features and (3) the cases of rapidly varying camera velocities. Towards solving those problems, this research presents the following four contributions that can be used individually, together, or combined with other approaches. A motion-only filter is devised by capitalizing on algebraic threading constraints. This filter efficiently integrates information over multiple frames achieving a performance comparable to the best state of the art filters. However, unlike other filter based approaches, it is not affected by large baselines (displacement between camera centers). An approach is introduced to incorporate, with only a small computational overhead, a large number of frame-to-frame features (i.e., features that are matched only in pairs of consecutive frames) in any analytic filter. The computational overhead grows linearly with the number of added frame-to-frame features and the experimental results show an increased accuracy and consistency. A novel filtering approach scalable to accommodate a large number of features is proposed. This approach achieves both the scalability of the state of the art filter in scalability and the accuracy of the state of the art filter in accuracy. A solution to the problem of prediction over large baselines in monocular Bayesian filters is presented. This problem is due to the fact that a simple prediction, using constant velocity models for example, is not suitable for large baselines, and the projections of the 3D points that are in the state vector can not be used in the prediction due to the need of preserving the statistical independence of the prediction and update steps.

Simultaneous localization and mapping (SLAM) and Structure from Motion (SfM) are important problems in robotics and computer vision. One of the challenges is to solve a large-scale optimization problem associated with all of the robot poses, camera parameters, landmarks and measurements. Yet neither of the two reigning paradigms, direct and iterative methods, scales well to very large and complex problems. Recently, the subgraph-preconditioned conjugate gradient method has been proposed to combine the advantages of direct and iterative methods. However, how to find a good subgraph is still an open problem. The goal of this dissertation is to address the following two questions: (1) What are good subgraph preconditioners for SLAM and SfM? (2) How to find them? To this end, I introduce support theory and support graph theory to evaluate and design subgraph preconditioners for SLAM and SfM. More specifically, I make the following contributions: First, I develop graphical and probabilistic interpretations of support theory and used them to visualize the quality of subgraph preconditioners. Second, I derive a novel support-theoretic metric for the quality of spanning tree preconditioners and design an MCMC-based algorithm to find high-quality subgraph preconditioners. I further improve the efficiency of finding good subgraph preconditioners by using heuristics and domain knowledge available in the problems. Our results show that the support-theoretic subgraph preconditioners significantly improve the efficiency of solving large SLAM problems. Third, I propose a novel Hessian factor graph representation, and use it to develop a new class of preconditioners, generalized subgraph preconditioners, that combine the advantages of subgraph preconditioners and Hessian-based preconditioners. I apply them to solve large SfM problems and obtain promising results. Fourth, I develop the incremental subgraph-preconditioned conjugate gradient method for large-scale online SLAM problems. The main idea is to combine the advantages of two state-of-the-art methods, incremental smoothing and mapping, and the subgraph-preconditioned conjugate gradient method. I also show that the new method is efficient, optimal and consistent. To sum up, preconditioning can significantly improve the efficiency of solving large-scale SLAM and SfM problems. While existing preconditioning techniques do not utilize the problem structure and have no performance guarantee, I take the first step toward a more general setting and have promising results.

Made available in DSpace on 2014-06-12T15:55:49Z (GMT). No. of bitstreams: 2 arquivo2328_1.pdf: 4997289 bytes, checksum: 4012a5235a1aad082afe66cac56457eb (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2010 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A reconstrução 3D é uma área de pesquisa que consiste em recuperar modelos que representem com precisão e em 3D características de interesse de uma cena, através da extração de informações 3D a partir de imagens 2D. Estas informações podem ser relativas à estrutura de uma determinada cena, posicionamento e trajetória de câmeras, textura, dentre outras. Uma vez de posse de tais informações, podemos utilizá-las para os mais diversos fins, por exemplo, modelagem automática de objetos, sistemas de navegação autônoma de robôs, modelos computacionais de estruturas ou órgãos do corpo humano, posicionamento de elementos virtuais em cenas reais, dentre outros. Uma das formas mais difundidas de se realizar reconstrução 3D é utilizando sequências contíguas de imagens ou vídeos capturados por câmeras convencionais (monoculares). Neste tipo de reconstrução um dos desafios mais importantes é o rastreamento. Rastreamento é a capacidade de conseguir corresponder um conjunto de pontos em uma sequência de imagens, ou seja, dado um ponto A com coordenadas x e y, deve-se ser capaz de identificar o ponto A com coordenadas x e y na imagem seguinte da sequência, e que corresponde exatamente à mesma localidade da estrutura sendo rastreada. Neste contexto, o objetivo desta dissertação de mestrado foi avaliar os algoritmos de rastreamento mais utilizados para este propósito, ressaltando as características individuais de cada um deles e identificando as vantagens e limitações que possuem. Os resultados desta análise podem ser uma ferramenta de auxílio na escolha do algoritmo de rastreamento a ser utilizado quando do desenvolvimento de uma solução de reconstrução 3D, tendo como base o domínio do problema que se deseja atacar. Os três algoritmos analisados foram o SIFT, o KLT e outro Baseado em Similaridade. Foi desenvolvida uma ferramenta de reconstrução 3D baseada em SfM. Esta ferramenta foi utilizada para a coleta de resultados com o rastreamento sendo realizado com SIFT, KLT e Similaridade. Uma etapa importante deste processo foi a definição de um conjunto de métricas para a análise comparativa dos algoritmos. As características individuais de rastreamento de cada um deles trouxeram bons resultados em alguns dos cinco cenários utilizados. Porém, no geral, o rastreador que apresentou os melhores resultados foi o KLT. Uma análise detalhada sobre os resultados desses algoritmos quando empregados para reconstrução 3D é apresentada

Made available in DSpace on 2014-06-12T15:56:46Z (GMT). No. of bitstreams: 2 arquivo2987_1.pdf: 8666109 bytes, checksum: 33e00abd7fc7fd3d0c5b1e545e26b856 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2010 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Reconstrução 3D é uma área de pesquisa que engloba várias técnicas com o propósito de recuperar modelos que representem precisamente um objeto ou um cenário em três dimensões, enfatizando características de interesse como, por exemplo, a forma, a textura ou a estrutura. O cerne de algoritmos de Struture from Motion (SfM), que é um tipo de técnica de reconstrução 3D bastante promissor, visa a obtenção da geometria 3D da cena a partir de um conjunto de imagens bidimensionais, além da posição e orientação da câmera no momento da captura. Para cada par de imagens é possível estimar a profundidade de um ponto conhecendo-se os parâmetros intrínsecos e extrínsecos da câmera e as coordenadas bidimensionais referentes a um mesmo ponto em cada foto, apesar de não ser possível determinar o tamanho real do objeto. Além disso, cada par de imagens produz uma reconstrução em um sistema de coordenadas distinto. Portanto, devido a essa falta de escala uniforme e das câmeras estarem em bases diferentes, é necessária a utilização de algoritmos que levem as câmeras para uma mesma base de referência, ou seja, que alinhem as câmeras e que criem uma reconstrução completa, pois, há pontos em algumas imagens que não são contemplados por outras. Esta dissertação de mestrado descreve os esforços empregados na investigação dos principais algoritmos de alinhamento, sua implementação e o aperfeiçoamento dos mesmos quando necessário, além de identificar o quão preciso é cada método. Entre as técnicas propostas na literatura foram utilizadas quatro abordagens, uma baseada na composição das matrizes de pose, duas baseadas na matriz de homografia e uma na correspondência entre os pontos 2D e os pontos 3D. Cada algoritmo se baseia em diferentes técnicas que resultam em matrizes de câmera distintas que ao serem fatoradas definem uma translação e a rotação semelhante. A fim de melhorar a precisão dos resultados gerados, foi utilizado o Sparse Bundle Adjustment (SBA) ao final de cada método. Para analisar os algoritmos, foi definida uma metodologia de comparação com métricas que avaliam os resultados não só qualitativamente como quantitativamente. Os critérios propostos foram a comparação dos pontos reconstruídos com o ground-truth, a análise dos erros de projeção e epipolar, as poses das câmeras e o tempo de execução. A metodologia foi aplicada tanto para dados sintéticos quanto para dados reais e, todos obtiveram resultados visualmente coerentes. Porém, a técnica de 2D3D se mostrou com resultados mais precisos

Submitted by Alice Araujo (alice.caraujo@ufpe.br) on 2018-01-17T17:28:49Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Tese Ivaneide de Oliveira Santos Geociencias 2017.pdf: 9682973 bytes, checksum: 9d343367dc127b6a931f4d2772559a33 (MD5) / Made available in DSpace on 2018-01-17T17:28:49Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Tese Ivaneide de Oliveira Santos Geociencias 2017.pdf: 9682973 bytes, checksum: 9d343367dc127b6a931f4d2772559a33 (MD5) Previous issue date: 2017-06-20 / CAPES / As Geociências, no âmbito da inventariação, da valorização do Patrimônio Geológico e da representação da Geodiversidade, utilizam-se de ferramentas e metodologias específicas que buscam atender, de um lado, as demandas que norteiam as rotinas do pesquisador através de formulários de inventariação, softwares, etc. e, por outro lado, as demandas que inferem na perspectiva dos diferentes públicos-alvo, através de tabelas, mapas, sites, blogs, teses, livros, figuras, vídeos, artigos, textos, notas científicas, etc. Entretanto, cada vez mais, as Geociências e, consequentemente, os públicos-alvo, têm-se diversificado e evoluído no sentido das novas tecnologias e novas formas de acesso à informação. Neste sentido, as tecnologias da informação, da comunicação e dos sistemas de informações geográficas, juntamente com suas diversas ferramentas, acrescentam novas formas de aquisição e tratamento de informação, novos produtos e integração de elementos que complementam a informação inerente ao inventário do Patrimônio Geológico. A caracterização de aspectos Geológicos, Geomorfológicos, Geográficos, de caráter científico e/ou educacional, beneficia desta integração, pois permite uma visão mais ampla, diversificada e agregada da informação disponível. Possibilita ainda, novas formas de representação destes aspectos e do Patrimônio Geológico, como também diversifica as formas de valorização dos aspectos geoturísticos. O trabalho, tem como objetivo desenvolver uma nova metodologia para a exibição de informações on-line de sítios de Geodiversidade integrando a representação de estruturas em 3D, fotogrametria, informação SIG e imagens panorâmicas utilizando realidade aumentada integrando produtos utilizáveis por todos os tipos de público e com fácil interatividade.Diante deste cenário, foram utilizadas algumas informações coletadas em sítios de geodiversidade na região do Cânion do Rio São Francisco (Nordeste brasileiro), Fafe e Geoparque Macedo dos Cavaleiros (Norte de Portugal) e, posteriormente, aplicadas as ferramentas de edição de imagens (Photoshop, Corel 6., etc.), de Sistemas de Informações Geográficas (SIG), neste caso o Quantum GIS e de fotogrametria para restituição tridimensional. Com base neste trabalho, foi desenvolvida informação online, com recurso às linguagens Java script, html5, WebCL, que permitiu a integração de uma visita virtual a áreas de interesse geológico, com integração de elementos multimídia. Estes conteúdos podem ser utilizados durante o planejamento do inventário do Patrimônio Geológico, ou podem ser explorados numa plataforma online interativa, onde a reunião de elementos fotográficos, obtidos com veículos aéreos não tripulados (VANT), imagens panorâmicas a 360º interpretadas, modelos de representação tridimensional, elementos cartográficos e elementos informativos, promovem uma nova forma de representação dos aspectos Geomorfológicos, Geológicos ou do Patrimônio Geológico. A obtenção de dados de imagem para a produção de panorâmicas interativas a 360º e modelos tridimensionais foi realizada com recurso a veículos aéreos não tripulados (VANT). / Geosciences, in the scope of the inventory, the appreciation of the Geological Heritage and representation of Geodiversity, use specific tools and methodologies that seek to meet on the one hand, demands that guide the routines of the researcher through inventory forms, software, etc. and, on the other hand, the demands that emerge from the perspective of different target audiences, through tables, maps, websites, blogs, thesis, books, pictures, videos, articles, texts, scientific notes, etc. However, increasingly, the Geosciences and hence the target audiences, have diversified and evolved towards the use of new technologies, tools and new forms of access to information. In this sense, information technology, communication and geographic information systems, along with its various tools, add new ways of acquiring and processing information, new products and integration of elements that complement the inherent information to the inventory of the Geological Heritage. The characterization of Geological, Geomorphological or Geographical aspects, of scientific and/or educational nature, benefits from this integration, as it allows a broader view, more diverse and aggregated way of organize the available information. It also enables new forms of representation of these aspects and the Geological Heritage, as well as diversify the forms of promoting geotouristic aspects. In this scenario, we used the information collected in the inventory of geological heritage, held under Brilhas’s method (2005), of scientific interest sites in Canion region of San Francisco, and then apply image editing tools (Photoshop, Corel 6, etc.), Geographic Information Systems (GIS), in this case the Quantum GIS and photogrammetry applications for three- dimensional modelling. Based on this work, online information was developed, using the Javascript, html5, WebCL languages, which allowed the creation of a virtual visit to areas of geological interest, with integration of multimedia elements. This content allows the use in the planning of the inventory of the Geological Heritage, or it can be explored in an interactive online platform, where the assemblage of photographic elements, interpreted interactive 360º panoramic images, three-dimensional models, cartographic elements and pieces of information, promote a new form of representation of geomorphological and geological aspects or Geological Heritage. Obtaining photographic elements, intended for interactive panoramic images and 3D models, was performed using unmanned aerial vehicles (UAV).

Remotely sensing recent growth, herbivory, or disturbance of herbaceous and woody vegetation in dryland ecosystems requires high spatial resolution and multi-temporal depth. Three dimensional (3D) remote sensing technologies like lidar, and techniques like structure from motion (SfM) photogrammetry, each have strengths and weaknesses at detecting vegetation volume and extent, given the instrument's ground sample distance and ease of acquisition. Yet, a combination of platforms and techniques might provide solutions that overcome the weakness of a single platform. To explore the potential for combining platforms, we compared detection bias amongst two 3D remote sensing techniques (lidar and SfM) using three different platforms [ground-based, small unmanned aerial systems (sUAS), and manned aircraft]. We found aerial lidar to be more accurate for characterizing the bare earth (ground) in dense herbaceous vegetation than either terrestrial lidar or aerial SfM photogrammetry. Conversely, the manned aerial lidar did not detect grass and fine woody vegetation while the terrestrial lidar and high resolution near-distance (ground and sUAS) SfM photogrammetry detected these and were accurate. UAS SfM photogrammetry at lower spatial resolution under-estimated maximum heights in grass and shrubs. UAS and handheld SfM photogrammetry in near-distance high resolution collections had similar accuracy to terrestrial lidar for vegetation, but difficulty at measuring bare earth elevation beneath dense herbaceous cover. Combining point cloud data and derivatives (i.e., meshes and rasters) from two or more platforms allowed for more accurate measurement of herbaceous and woody vegetation (height and canopy cover) than any single technique alone. Availability and costs of manned aircraft lidar collection preclude high frequency repeatability but this is less limiting for terrestrial lidar, sUAS and handheld SfM. The post-processing of SfM photogrammetry data became the limiting factor at larger spatial scale and temporal repetition. Despite the utility of sUAS and handheld SfM for monitoring vegetation phenology and structure, their spatial extents are small relative to manned aircraft.

Northwestern Arctic Canada is one of the most rapidly warming regions in the Arctic (Serreze et al., 2009). Retrogressive thaw slumps (RTS) are one of the most dramatic thermokarst features in permafrost terrain (Kokelj et al., 2013). Many studies have focused on describing the distribution of thermokarst landscapes (i.e., Olefeldt et al., 2016), as well as change in thermokarst terrain over the historical record (i.e., Kokelj and Jorgenson, 2013). However, improved high temporal and spatial resolution monitoring of thaw slump activity is required to enhance our understanding of factors governing their growth. Recent advances in aerial and ground-based Structure from Motion (SfM), a photogrammetry application, allow for temporal and spatial high-resolution characterization of landscape changes. This thesis explores two methods in SfM photogrammetry: 1) aerial imaging using an unmanned aerial vehicle (UAV) and 2) ground-based imaging using stationary multi-camera time-lapse installations, to derive high-resolution temporal and spatial data for change detection. A trend in mean elevation change was produced, and agrees with the RTS behaviour over the study period, which supports the viability of the proposed capture method. The lack of congruency in data range suggests need for further development in terms of analyses and differencing algorithms employed. The proposed method may be feasible for employment in other fields of science in which high temporal resolution change detection is desired. This proof of concept study was conducted at a small slump on the Peel Plateau, NWT, Canada, and aims to enhance understanding of the development and perpetuation of thaw slumps, to better anticipate landscape and ecosystem responses to future climate change.

Submitted by Pedro Barros (pedro.silvabarros@ufpe.br) on 2018-09-21T20:45:56Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) TESE Ivaneide de Oliveira Santos.pdf: 9682973 bytes, checksum: 9d343367dc127b6a931f4d2772559a33 (MD5) / Approved for entry into archive by Alice Araujo (alice.caraujo@ufpe.br) on 2018-09-24T18:46:47Z (GMT) No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) TESE Ivaneide de Oliveira Santos.pdf: 9682973 bytes, checksum: 9d343367dc127b6a931f4d2772559a33 (MD5) / Made available in DSpace on 2018-09-24T18:46:47Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) TESE Ivaneide de Oliveira Santos.pdf: 9682973 bytes, checksum: 9d343367dc127b6a931f4d2772559a33 (MD5) Previous issue date: 2017-06-20 / CAPES / As Geociências, no âmbito da inventariação, da valorização do Patrimônio Geológico e da representação da Geodiversidade, utilizam-se de ferramentas e metodologias específicas que buscam atender, de um lado, as demandas que norteiam as rotinas do pesquisador através de formulários de inventariação, softwares, etc. e, por outro lado, as demandas que inferem na perspectiva dos diferentes públicos-alvo, através de tabelas, mapas, sites, blogs, teses, livros, figuras, vídeos, artigos, textos, notas científicas, etc. Entretanto, cada vez mais, as Geociências e, consequentemente, os públicos-alvo, têm-se diversificado e evoluído no sentido das novas tecnologias e novas formas de acesso à informação. Neste sentido, as tecnologias da informação, da comunicação e dos sistemas de informações geográficas, juntamente com suas diversas ferramentas, acrescentam novas formas de aquisição e tratamento de informação, novos produtos e integração de elementos que complementam a informação inerente ao inventário do Patrimônio Geológico. A caracterização de aspectos Geológicos, Geomorfológicos, Geográficos, de caráter científico e/ou educacional, beneficia desta integração, pois permite uma visão mais ampla, diversificada e agregada da informação disponível. Possibilita ainda, novas formas de representação destes aspectos e do Patrimônio Geológico, como também diversifica as formas de valorização dos aspectos geoturísticos. O trabalho, tem como objetivo desenvolver uma nova metodologia para a exibição de informações on-line de sítios de Geodiversidade integrando a representação de estruturas em 3D, fotogrametria, informação SIG e imagens panorâmicas utilizando realidade aumentada integrando produtos utilizáveis por todos os tipos de público e com fácil interatividade.Diante deste cenário, foram utilizadas algumas informações coletadas em sítios de geodiversidade na região do Cânion do Rio São Francisco (Nordeste brasileiro), Fafe e Geoparque Macedo dos Cavaleiros (Norte de Portugal) e, posteriormente, aplicadas as ferramentas de edição de imagens (Photoshop, Corel 6., etc.), de Sistemas de Informações Geográficas (SIG), neste caso o Quantum GIS e de fotogrametria para restituição tridimensional. Com base neste trabalho, foi desenvolvida informação online, com recurso às linguagens Java script, html5, WebCL, que permitiu a integração de uma visita virtual a áreas de interesse geológico, com integração de elementos multimídia. Estes conteúdos podem ser utilizados durante o planejamento do inventário do Patrimônio Geológico, ou podem ser explorados numa plataforma online interativa, onde a reunião de elementos fotográficos, obtidos com veículos aéreos não tripulados (VANT), imagens panorâmicas a 360º interpretadas, modelos de representação tridimensional, elementos cartográficos e elementos informativos, promovem uma nova forma de representação dos aspectos Geomorfológicos, Geológicos ou do Patrimônio Geológico. A obtenção de dados de imagem para a produção de panorâmicas interativas a 360º e modelos tridimensionais foi realizada com recurso a veículos aéreos não tripulados (VANT). / Geosciences, in the scope of the inventory, the appreciation of the Geological Heritage and representation of Geodiversity, use specific tools and methodologies that seek to meet on the one hand, demands that guide the routines of the researcher through inventory forms, software, etc. and, on the other hand, the demands that emerge from the perspective of different target audiences, through tables, maps, websites, blogs, thesis, books, pictures, videos, articles, texts, scientific notes, etc. However, increasingly, the Geosciences and hence the target audiences, have diversified and evolved towards the use of new technologies, tools and new forms of access to information. In this sense, information technology, communication and geographic information systems, along with its various tools, add new ways of acquiring and processing information, new products and integration of elements that complement the inherent information to the inventory of the Geological Heritage. The characterization of Geological, Geomorphological or Geographical aspects, of scientific and/or educational nature, benefits from this integration, as it allows a broader view, more diverse and aggregated way of organize the available information. It also enables new forms of representation of these aspects and the Geological Heritage, as well as diversify the forms of promoting geotouristic aspects. In this scenario, we used the information collected in the inventory of geological heritage, held under Brilhas’s method (2005), of scientific interest sites in Canion region of San Francisco, and then apply image editing tools (Photoshop, Corel 6, etc.), Geographic Information Systems (GIS), in this case the Quantum GIS and photogrammetry applications for three- dimensional modelling. Based on this work, online information was developed, using the Javascript, html5, WebCL languages, which allowed the creation of a virtual visit to areas of geological interest, with integration of multimedia elements. This content allows the use in the planning of the inventory of the Geological Heritage, or it can be explored in an interactive online platform, where the assemblage of photographic elements, interpreted interactive 360º panoramic images, three-dimensional models, cartographic elements and pieces of information, promote a new form of representation of geomorphological and geological aspects or Geological Heritage. Obtaining photographic elements, intended for interactive panoramic images and 3D models, was performed using unmanned aerial vehicles (UAV).

In current forensic practice, there are few standards for outdoor crime scene documentation, despite the need for such documentation to be accurate and precise in order to preserve evidence. A potential solution to this is the implementation of image-based photogrammetry. Applied Structure from Motion (SfM) reconstructs models through image point comparisons. A 3D model is produced from a reference photoset that captures a 360-degree view of the subject and the software employs triangulation to match specific points, datums, across individual photos. The datums are arranged into a point-cloud that is then transformed into the final model. Modifying the point-cloud into a final product requires algorithms that adjust the points by building a textured mesh from them. One of the disadvantages of SfM is that the point-cloud can be “noisy,” meaning that the program is unable to distinguish the features of one datum from another due to similarities, creating coverage gaps within the meshed images. To compensate for this, the software can smooth portions of the model in a best-guess process during meshing. As commercial software does not disclose the adjustment algorithms, this documentation technique, while very useful in other disciplines that regularly apply SfM such as archaeology, would fail to meet the standards of the Daubert and Kumho criteria in a forensic setting. A potential solution to this problem is to use open-source software, which discloses the adjustment algorithms to the user. It was hypothesized that the output of open-sourced software solutions would as accurate as the models produced with commercial software and with total station mapping techniques. To evaluate this hypothesis, a series of mock outdoor crime scenes were documented using SfM and traditional mapping techniques. The scenes included larger surface scatter and small surface scatter scenes. The large surface scatter scenes contained a dispersed set of plastic human remains, and various objects that might reasonably be associated with a crime scene. Ten of these scenes were laid out in 10 x 10 m units in a New England forested environment, each grid with a slightly different composition, and then documented using an electronic total station, data logger and digital camera. The small surface scatter scenes consisted of a pig mandible placed in different environments across two days of data collection. The resulting models were built using PhotoScan by AgiSoft, the commercial software, and MicMac for Mac OSX as the open-source comparison software. Accuracy is only part of the concern however; the full utility of any one of the workflows is defined additionally by the overall cost-effectiveness (affordability and accessibility) and the visual quality of the final model. Accuracy was measured by the amount of variance in fixed-datum measurements that remained consistent across scenes, whereas visual quality of the photogrammetric models were determined by cloud comparison histograms, which allows for comparison of models between software types and across different days of data collection. Histograms were generated using CloudCompare. Not all models that were rendered were useable—90% of large surface scatter models and 87.5% of small surface scatter models were useable. While there was variance in the metric outputs between the total station and photogrammetric models, the average total variance in fixed-datum lengths for individual scenes was below 0.635 cm for six of the ten scenes. However, only one of the large surface scatter scenes produced measurement that were significantly different between the total station measurements and the software measurement. The maximum differences in measurement between the total station and software measurements were 0.0917 m (PhotoScan) and 0.178 m (MicMac). The minimum difference that was found for either software was 0.000 m, indicating exact measurement. The histograms for the large scatter scenes were comparable, with the commercial and open-source software-derived models having low standard deviations and mean distances between points. For the small surface scatter scenes, the histograms between software types varied depending on the environment and the lighting conditions on the day of data collection. Conditions such as light, ground foliage and topography affect model quality significantly, as well as the amount of available computing power. No such issues of losing objects or limitations of computing power were encountered when mapping by total station and processing the data in AutoCAD. This research shows that SfM has the potential to be a rapid, accurate and low-cost resource for forensic investigation. SfM methodology for outdoor crime scene documentation can be adapted to fit within evidentiary criteria through the use of open-source software and transparent processing, but there are limitations that must be taken into consideration.