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This paper presents a 3D computer vision method that assists the tedious procedure of manually reconstructing ceramic vessels from fragments unearthed in an archaeological excavation. This computational method relies on vessel surface markings combined with expert feedback (via the archaeologist) to form a generic model of a vessel that the excavated fragments might have originated from. Prior expert...
We present a novel method for computing the Minkowski Functionals from isodensity surfaces extracted directly from the Delaunay tessellation of a point distribution. This is an important step forward compared to the previous cosmological studies when the isodensity surface was built in the field on a uniform cubic grid and therefore having a uniform spatial resolution. The density field representing...
We study the topology of the Megaparsec Cosmic Web on the basis of the Alpha Shapes of the galaxy distribution. The simplicial complexes of the alpha shapes are used to determine the set of Betti numbers (βk, k = 1,...,D) which represent a complete characterization of the topology of a manifold. This forms a useful extension of the geometry and topology of the galaxy distribution by Minkowski functionals,...
N-sided hole filling plays an important role in vertex blending. Piegl and Tiller presented an algorithm to interpolate the given boundary and cross-boundary derivatives in B-spline form. To deal with the incompatible cases that their algorithm cannot handle, we propose an extension method to manipulate the transition between sharp and rounded features. The algorithm first patches n crescent-shaped...
Finding fiducial facial points in any frame of a video showing rich naturalistic facial behaviour is an unsolved problem. Yet this is a crucial step for geometric-feature-based facial expression analysis, and methods that use appearance-based features extracted at fiducial facial point locations. In this paper we present a method based on a combination of Support Vector Regression and Markov Random...
Piecewise cubic and quartic polynomial curves with adjustable interpolation points are presented in this paper. The adjustable interpolation points are represented by local shape parameters and the given control points. Based on the choice of endpoint tangents of curve segments, piecewise cubic C1, piecewise cubic G2 and piecewise quartic C2 curves are given. The representations of the piecewise cubic...
This paper studies the effect of different color fringe projection sequences for 3D shape measurement of general objects. A novel color correction method is also presented for reducing the image color errors induced from color coupling effect and color imbalance effect. First, three sequences of projected fringe patterns, including basic projection sequence, disordered projection sequence and ordered...
Subdividing surfaces into cylinders is a significant question in various applications. Even if specific approaches have been described in several domains, most of the time topological properties are not explicitly handled, and the segmentation remains mainly driven by geometry. We present here an original approach to describe the topological and combinatorial nature of a tiling with cylinders. We...
The Voronoi Treemap is a space-filling treemap technique that relaxes the constraints of rectangular nodes. Its organic shapes maintain a one-to-one aspect ratio, are flexible with their placement, allowing stable zooming and dynamic data values. In this paper, we present algorithms for efficient computation and dynamic update of Voronoi Treemaps. Our GPGPU-based technique allows for rapid computation...
Two dimensional shape models have been successfully applied to solve many problems in computer vision such as object tracking, recognition and segmentation. Typically, 2D shape models (e.g. Point Distribution Models, Active Shape Models) are learned from a discrete set of image landmarks once the rigid transformations are removed applying Procrustes Analysis (PA). However, the standard PA process...
Methodology for fusing multiple segmentations to produce an improved result has been useful in computational anatomical studies. Although obtaining segmentations of anatomy having a particular topology are essential to studies using diffeomorphic deformation based analyses, no methods of label fusion presented to date have incorporated information regarding the topology of the anatomy. In this paper,...
We describe a method to compute the prototypical shapes for object categories using the shock graph representation. Given a set of category exemplars, we determine a prototypical shape for this category by estimating the Karcher mean of the shock graphs of the exemplar shapes. The method is described in three steps. First, we derive an iterative method to average N points in an abstract continuous...
This paper reviews the concept of straight skeletons, which is well known in computational geometry, and applies it to binary shapes that are used in vision-based shape and object recognition. We devise a novel algorithm for computing discrete straight skeletons from binary input images, which is based on a polygonal approximation of the input shape and a hybrid method that combines continuous and...
We recognize actions and activities in video sequences as distinguishing patterns in the 3D spatiotemporal volume of motion energy. Local motion descriptors, which capture highly discriminative invariant motion characteristics in a spherical neighborhood, are computed in the 3D volume at points of salient motion to represent actions or activities in video sequences. Two actions are then matched based...
We present a contour based approach to object recognition in real-world images. Contours are represented by generic shape primitives of line segments and ellipses. These primitives offer substantial flexibility to model complex shapes. We pair connected primitives as shape tokens, and learn category specific combinations of shape tokens. We do not restrict combinations to have a fixed number of tokens,...
Multiple surface searching with only image intensity information is a difficult job in the presence of high noise and weak edges. We present in this paper a novel method for globally optimal multi-surface searching with a shape prior represented by convex pairwise energies. A 3-D graph-theoretic framework is employed. An arc-weighted graph is constructed based on a shape model built from training...
This paper describes how phase-sensitive rotation invariants for three-dimensional data may be obtained. A “bispectrum” is formulated for rotations, and its properties are derived for spherical harmonic coefficients as well as for moments. The bispectral invariants offer improved discrimination over previously published magnitude-only invariants. They are able to distinguish rotations from reflections,...
The integral image is typically used for fast integrating a function over a rectangular region in an image. We propose a method that extends the integral image to do fast integration over the interior of any polygon that is not necessarily rectilinear. The integration time of the method is fast, independent of the image resolution, and only linear to the polygon's number of vertices. We apply the...
Geometry line modeling technique is basically a kind of important modeling application when proceeding space complex object construction. First, paper introduced rules for building VRML virtual line model, including IndexedLineSet node's function and its syntax format etc. Here we mainly discussed some of IndexedLineSet node's important fields' meaning, for example coord and coordIndex field, color...
In this paper, we proposed a new physical simulation method that can model non-convex configuration space. The new method employs a novel contact model that take into account geometry information of objects. It can also be shown that it reduces the work for collision detection routines.
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