Reconstruction of Outdoor Sculptures from Silhouettes under Approximate Circular Motion of an Uncalibrated Hand-Held Camera

This paper presents a novel technique for reconstructing an outdoor sculpture from an uncalibrated image sequence acquired around it using a hand-held camera. The technique introduced here uses only the silhouettes of the sculpture for both motion estimation and model reconstruction, and no corner detection nor matching is necessary. This is very important as most sculptures are composed of smooth textureless surfaces, and hence their silhouettes are very often the only information available from their images. Besides, as opposed to previous works, the proposed technique does not require the camera motion to be perfectly circular (e.g., turntable sequence). It employs an image rectification step before the motion estimation step to obtain a rough estimate of the camera motion which is only approximately circular. A refinement process is then applied to obtain the true general motion of the camera. This allows the technique to handle large outdoor sculptures which cannot be rotated on a turntable, making it much more practical and flexible.postprin

Reconstruction of sculpture from its profiles with unknown camera positions

Profiles of a sculpture provide rich information about its geometry, and can be used for shape recovery under known camera motion. By exploiting correspondences induced by epipolar tangents on the profiles, a successful solution to motion estimation from profiles has been developed in the special case of circular motion. The main drawbacks of using circular motion alone, namely the difficulty in adding new views and part of the object always being invisible, can be overcome by incorporating arbitrary general views of the object and registering its new profiles with the set of profiles resulted from the circular motion. In this paper, we describe a complete and practical system for producing a three-dimensional (3-D) model from uncalibrated images of an arbitrary object using its profiles alone. Experimental results on various objects are presented, demonstrating the quality of the reconstructions using the estimated motion.published_or_final_versio

Reconstruction of Outdoor Sculptures from Silhouettes under Approximate Circular Motion of an Uncalibrated Hand-Held Camera

This paper presents a novel technique for reconstructing an outdoor sculpture from an uncalibrated image sequence acquired around it using a hand-held camera. The technique introduced here uses only the silhouettes of the sculpture for both motion estimation and model reconstruction, and no corner detection nor matching is necessary. This is very important as most sculptures are composed of smooth textureless surfaces, and hence their silhouettes are very often the only information available from their images. Besides, as opposed to previous works, the proposed technique does not require the camera motion to be perfectly circular (e.g., turntable sequence). It employs an image rectification step before the motion estimation step to obtain a rough estimate of the camera motion which is only approximately circular. A refinement process is then applied to obtain the true general motion of the camera. This allows the technique to handle large outdoor sculptures which cannot be rotated on a turntable, making it much more practical and flexible

Reconstructing Geometry from Its Latent Structures

Our world is full of objects with complex shapes and structures. Through extensive experience humans quickly develop an intuition about how objects are shaped, and what their material properties are simply by analyzing their appearance. We engage this intuitive understanding of geometry in nearly everything we do.It is not surprising then, that a careful treatment of geometry stands to give machines a powerful advantage in the many tasks of visual perception. To that end, this thesis focuses on geometry recovery in a wide range of real-world problems. First, we describe a new approach to image registration. We observe that the structure of the imaged subject becomes embedded in the image intensities. By minimizing the change in shape of these intensity structures we ensure a physically realizable deformation. We then describe a method for reassembling fragmented, thin-shelled objects from range-images of their fragments using only the geometric and photometric structure embedded in the boundary of each fragment. Third, we describe a method for recovering and representing the shape of a geometric texture (such as bark, or sandpaper) by studying the characteristic properties of texture---self similarity and scale variability. Finally, we describe two methods for recovering the 3D geometry and reflectance properties of an object from images taken under natural illumination. We note that the structure of the surrounding environment, modulated by the reflectance, becomes embedded in the appearance of the object giving strong clues about the object's shape.Though these domains are quite diverse, an essential premise---that observations of objects contain within them salient clues about the object's structure---enables new and powerful approaches. For each problem we begin by investigating what these clues are.We then derive models and methods to canonically represent these clues and enable their full exploitation. The wide-ranging success of each method shows the importance of our carefully formulated observations about geometry, and the fundamental role geometry plays in visual perception.Ph.D., Computer Science -- Drexel University, 201

Documentation of the Body Transformations during the Decomposition Process: From the Crime Scene to the Laboratory

Forensic science is defined as the application of scientific or technical practices to the recognition, collection, analysis, and interpretation of evidence for criminal and civil law or regulatory issues. A combination of computer science in the field of 3D reconstruction and molecular biology science and techniques were employed in this research aims to document and record a complete picture of the body decomposition process including the changes of the microbiome over the decomposition process. In this thesis, the possibility to reconstruct the crime scene and the decomposition process was investigated. In addition, a 3D model aiming to integrate the biological and thanatological information was generated. The possibility of utilising Autodesk 123D Catch software as a new tool for 3D reconstruction of a crime scene was thoroughly evaluated. First experiments demonstrated that the number of photos required to obtain the best result was specified to be from 20 to 30 photos as a minimum. In addition, significant experiments were performed in different conditions of sizes, locations, and different involved materials. The measurements were obtained from the models using the same software were compared with the real measurements of the tested objects. The result of the correlation between real and estimated measurements showed a very strong agreement ranging from 0.994 to 1.000. With reference to the documentation of the decomposition process, there are different factors, intrinsic and extrinsic, have been reported affecting the decomposition of a carrion/body. These factors mainly interact with the rates of the biological and chemical reaction happening after death. The biological reactions are mainly due to the activity of microorganism and insects. Pigs (Sus scrofa domesticus) were used as a model for human studies and the results obtained have been applied to other mammals without considering the effect of fur on the decomposition process and on the insect and microbial colonisation. In order to investigate this point, rabbits (Oryctolagus cuniculus) with and without fur were used in two sets of experiments at Huddersfield in summer 2014 and in spring 2015. The results obtained in this study showed a similarity of the decomposition stages between animals with and without fur. However, the decomposition process was faster during the summer due to the fast of insect colonisation and activity. In addition, the entomological data collected during the summer and spring experiments were demonstrated that the same taxa nearly were present in both seasons, except Hydrotaea (Diptera, Muscidae), which was presented only in the summer experiment, moreover, only one sample of Lucilia sericata (Calliphoridae) was detected in the spring season. Differences in colonisation time were observed only in spring experiment; animals without fur were colonised two days before animals with fur. The season could have affected the insect’s activity and the spread of the decomposition volatiles. The microbial communities during the decomposition process were investigated using BIOLOG EcoPlate™ and the hypervariable V1-3 region of 16S rRNA gene was used for their molecular identification based on pyrosequencing. Eurofins Genomic Operon using 454-GS Junior pyrosequencing platform (Roche) carried out these analyses. The functional diversity of the bacterial communities on all carcasses samples showed a considerable variability depending on the stage of the decomposition and the sampling region (Oral cavity, skin and interface-sand-carrion) in both seasons. Furthermore, over the molecular analyses of bacterial communities at the phylum level, four main phyla of bacteria were detected among analysed carrion during the decomposition process. These phyla were changed significantly during the stages of the decomposition and between sampling regions. While no difference was observed due to presence or absence of fur. On the other hand, the analysis at the family level was able to highlight differences at the temporal scale but as well as carrion with and without fur. The statistical analysis results showed a significant difference in the bacterial community family distribution among the presence of fur and among the decomposition stages, with significant differences among sampling regions and seasons