By Topic

Shape Modeling and Applications, 1997. Proceedings., 1997 International Conference on

Date 6-6 March 1997

Filter Results

Displaying Results 1 - 25 of 28
  • Proceedings of 1997 International Conference on Shape Modeling and Applications

    Save to Project icon | Request Permissions | PDF file iconPDF (184 KB)  
    Freely Available from IEEE
  • Author index

    Page(s): 251
    Save to Project icon | Request Permissions | PDF file iconPDF (48 KB)  
    Freely Available from IEEE
  • Fast algorithms for ridge detection

    Page(s): 189 - 197
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (684 KB)  

    We propose fast algorithms for the detection of view independent ridges on surfaces given by graphs of functions. The ridges are defined via extrema of the principal curvatures along the associated principal direction. These algorithms have the advantage to be fast and it appears that the so defined ridges deserve as a characteristic feature of the shape of the surface. Results on analytic surfaces and on real data are shown and discussed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Geometrical cloning of 3D objects via simultaneous registration of multiple range images

    Page(s): 130 - 139
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1224 KB)  

    Presents a method for the reconstruction of real-world objects from multiple range images. One major contribution of our approach is the simultaneous registration of all range images acquired from different scanner views. Thus, registration errors are not accumulated, and it is even possible to reconstruct large objects from an arbitrary number of small range images. The registration process is based on a least-squares approach where a distance metric between the overlapping range images is minimized. A resolution hierarchy accelerates the registration substantially. After registration, a volumetric model of the object is carved out. This step is based on the idea that no part of the object can lie between the measured surface and the camera of the scanner. With the marching cube algorithm, a polygonal representation is generated. The accuracy of this polygonal mesh is improved by moving the vertices of the mesh on to the surface implicitly defined by the registered range images View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Experimental study on acceleration of an exact-arithmetic geometric algorithm

    Page(s): 160 - 168
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (720 KB)  

    The paper presents a method for accelerating an exact arithmetic geometric algorithm. The exact arithmetic is one of the most promising approaches for making numerically robust geometric algorithms, because it enables us to always judge the topological structures of objects correctly and thus makes us free from inconsistency. However, exact arithmetic costs much more time than floating point arithmetic. In order to decrease this cost, the paper studies a hybrid method using both exact and floating point arithmetic. For each judgement in the algorithm, floating point arithmetic is first applied, and exact arithmetic is used only when the floating point computation is not reliable. This idea is applied to the construction of three dimensional convex hulls, and experiments show that 80~95% of the computational cost can be saved View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Towards a generic editor for subdivision surfaces

    Page(s): 37 - 46
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1712 KB)  

    Subdivision surfaces are defined by a mesh of points and by one or more refinement rules that substitute new, larger subsets of points for existing subsets to yield refined meshes. The refinement rules defining a subdivision surface are known collectively as the refinement process defining the surface. Refinement processes of interest are any for which the successively refined meshes can be shown to converge to a subdivision surface with known smoothness properties. The authors report on the progress of their investigations into software abstractions for refinement, providing for a generic editor to be implemented that can assist in the design of any subdivision surface View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Two shape metrics for biomedical outline data: bending energy, Procrustes distance, and the biometrical modeling of shape phenomena

    Page(s): 110 - 120
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1032 KB)  

    Quantitative studies of shapes in the real world are often expedited by the tools of morphometrics, a branch of multivariate statistics organized to exploit the origin of such data in real Euclidean geometry. This paper reviews one such tool that has recently been designed for the analysis of corresponding biological outlines of similar shape, such as those that arise from organ or tissue boundaries in medical images. The analysis is a hybrid of two morphometric tools, Procrustes analysis and the thin-plate spline, the properties of which are already well-understood separately. The thin-plate spline optimizes one shape metric, the Procrustes methods another. Their combination permits the averaging of groups of outlines, the rigorous display of sample variation around these averages in full detail, and rigorous multivariate statistical detection and testing of hypotheses linking those patterns to their putative causes or effects. The new tool is demonstrated using outlines of the corpus callosum (connection of the cerebral hemispheres) in mid-sagittal images of 12 normal human brains and 13 brains of schizophrenics View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The 3D revolution: CAD access for all!

    Page(s): 64 - 70
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (720 KB)  

    The manufacturing industry has invested vast amounts of resources in the deployment and use of solid modeling technology. Although expensive to generate and potentially very valuable in many product related activities, 3D models have rarely been exploited to support product management, documentation, collaborative review, and promotion, because they were only accessible to trained designers equipped with expensive graphics workstations. Intranet access, popular 3D exchange formats, and affordable 3D graphics chips permit to download and view 3D models using a personal computer. Although these basic capabilities are revolutionizing the entertainment and marketing industry and have reduced the cost of a design station, they are of little help to non-designers in the manufacturing industry. The author articulates a vision where 3D data is available and exploited at all phases of a product life cycle. The paper investigates the shortcomings of the current technology, identifies the fundamental research issues, and reviews recent advances in 3D data compression, in the automatic generation of levels-of-detail for interactive rendering, and in the innovative exploitation of 3D input devices for an intuitive and effective navigation View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Freehand sketch system for 3D geometric modelling

    Page(s): 55 - 62
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (604 KB)  

    The paper introduces a new method to deal with sketches for inputting geometric models at a workstation. The sketches are drawn on a CRT screen through a stylus pencil and a tablet by a designer at an early stage in the design procedure. The designer can keep the drawing stylus at a workstation as the same manner as using a pen on paper. The system `Sketch Interpreter' can correct geometric models in a computer even though input sketches are geometrically distorted. This system can create 3D geometric models in a computer even though input data of 2D sketches are drawn by freehand. The system is constructed in terms of three characteristic procedures on a workstation with a pointing device; (1) to recognize hand sketches on the screen. Freehand lines are drawn by pen operations from which a computer can construct a 3D geometric model. The first operation computes mathematical parameters for the projective transformation; (2) to construct additional geometric models by inputting more sketches drawn perspectively; and (3) to redraw modified geometric models replacing the sketch lines. The interactive methods are suitable for realistically constructing any geometric shapes that a designer imagines. Created data are transferred to an advanced 3D-CAD system. The system is applied as a front-end processor of design practice in fields such as office equipment View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Shape integration of multi stereo images using surveyed points for an archaeological site

    Page(s): 140 - 148
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1036 KB)  

    Proposes a new method for reconstructing complete 3D shapes and colors of outdoor objects, especially of archaeological sites, as a reconstructed 3D image can be useful for archaeological research. The method integrates two kinds of data: (1) partial surfaces (inaccurate object surfaces with color information which are obtained by stereogrammetry, each of which has its local geometry fixed on the roughly calibrated stereo cameras), and (2) surveyed points (sampled points whose 3D coordinate values are represented with the world geometry and accurately measured by a sensor). The authors focused on fitting the partial surfaces to the surveyed points, and adopted adjustment processes which contained two feedback loops. The method is applied to an outdoor 3D measurement of the Kamaato archaeological site View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ten questions that arose in designing the Djinn API for solid modelling

    Page(s): 71 - 76
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    Djinn is an API for solid modelling which is defined in the language of point-sets and is thus independent of any particular modelling data-structure (e.g. boundary representations or CSG trees). In designing this API, several significant and interesting questions have arisen, including: the basic feasibility of the approach; deciding how to support cellular models; providing facilities for navigation without traditional data-structures; addressing the problems of `tweaks' and blends; ensuring that labels are preserved under geometric operations; permitting regions in which changes to a model have taken place to be identified; coping with approximate models; deciding whether to support variational models; keeping sweeps and transforms within a reasonable domain; and providing facilities to handle the many types of parametric surface. These questions are not all fully answered, but progress continues towards a published interface and C++ language binding View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Recognizing three-dimensional shapes while measuring them

    Page(s): 170 - 177, 247
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (856 KB)  

    The paper proposes a system that recognizes three dimensional (3D) objects while measuring them. The system consists of a liquid crystal (LC) projector and a video camera. Our system can be applied to moving objects. The system itself can also move while measuring the objects to obtain the data of a whole scene. In our system, range data is registered on the fly View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Bezier normal vector surface and its applications

    Page(s): 26 - 35
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (964 KB)  

    One of the essential properties of a surface is its normal vector. Many applications, i.e., surface rendering, surface-surface intersection, and offset surface generation, require normal vectors. A normal vector at a point on a tensor product surface is usually obtained by taking a cross product of the two partial derivatives. The paper discusses a Bezier normal vector surface which is a locus of an unnormalized cross product normal vector. It also explains several applications of the Bezier normal vector surface, such as detection and computation of degenerate normal vectors which cannot be calculated by the cross product, and an algorithm to find all critical points which are key points to solve the problems on surface-surface intersection View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Warping as a modelling tool for CSG/implicit models

    Page(s): 205 - 213, 248
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1172 KB)  

    Freeform deformations are useful for describing a class of complex motions within an animation system. Such deformations have been described using a generalization of parametric surfaces and their application to modeling is well documented. We present a method that can be applied to implicit surfaces which are defined as an iso surface around a set of skeletal elements. The resulting surface is approximated by a polygon mesh. Shape distortions, such as “squash and stretch” are applied automatically to models in motion by warping the space in which the models exist. A model will change its shape as the function defining the warped space can change over time or the model will deform as it moves through the warped space. Our system also treats groups of skeletal implicit primitives as CSG primitives. Warping can also be applied to these primitives. Different warp functions, for example bend, taper and twist can be applied locally or globally, the contribution from each primitive is calculated using a set of warp functions associated with that primitive. The interesting shapes, and possibly nonlinear motion obtained from space warping, would be difficult to reproduce using other techniques View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Efficient shape-based algorithms for modeling patient specific anatomy from 3D medical images: applications in virtual endoscopy and surgery

    Page(s): 97 - 108, 245-6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3360 KB)  

    Virtual reality environments provide highly interactive, natural control of the visualization process, significantly enhancing the scientific value of the data produced by medical imaging systems. Due to the computational and real-time display update requirements of virtual reality interfaces, the complexity of organ and tissue surfaces which can be displayed is limited. In this paper, we present two new algorithms for the production of anatomic surface models containing a pre-specified number of polygons from patient- or subject-specific volumetric image data sets. The advantage of these algorithms is that they efficiently tile complex surfaces with a specified number of polygons selected to optimize the trade-off between surface detail and real-time display rates. Surface detail is preserved by extracting key shape features from the segmented objects, which adaptively constrains the model tilers. To illustrate the utility of these models, we present an overview of their application in computed endoscopy and surgery planning as developed in the Virtual Reality Assisted Surgery Program (VRASP) in the Biomedical Imaging Resource View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Topological modelling of disordered cellular structures

    Page(s): 2 - 9
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (668 KB)  

    The authors model the structure of space-filling disordered cellular systems. These systems are cellular networks with minimum incidence numbers (D+1 edges incident on a vertex in D-dimension). In the literature such systems are known as froths since the soap froth is the archetype of these structures. They present a method where the structure of froths is analyzed as organized in concentric layers of cells around a given, arbitrary, central cell. A simple map gives, by recursion, the number of cells in each layer. The map has one parameter, given as a function of the average topological properties of the cells in the neighbouring layers. From the behaviour of the number of cells per layer with the topological distance, one obtains the curvature of the space tiled by the froth. By using the map it is therefore possible to characterize the shape of the manifold tiled by the froth in term of the topological arrangements of its tiles. In two dimensions, they propose a method to deduce the Gaussian curvature of surfaces from a set of sampled points. In three dimensions, they use the map to investigate the freedom in constructing disordered Euclidean cellular structures. Among the closed packed structures, they find the average shape of the cells that maximize this freedom in filling space View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Homotopic shape deformation

    Page(s): 215 - 225, 249
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1456 KB)  

    An image warping method is presented that deforms an image continuously without foldover while observing a given set of trajectories of feature elements. Any intermediate image during the morph is homeomorphic to the initial image and the morphing process is a homotopy. The method permits points, line segments, and polygons to be included as features in the image. Techniques are described to make the deformation process smooth in spatial as well as temporal dimensions. An experimental result is included to demonstrate the feasibility of our approach and complexity of the algorithm is analyzed. Morphing between images that are topologically unequivalent is also briefly discussed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Collaborative visualization and modeling

    Page(s): 178 - 187
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1196 KB)  

    Rapid advances in computing hardware (workstations, PCs), infrastructure (networks, cable, telephone), product development software (geometric modeling, process simulations, graphics), and business models (emerging economies, international currency exchange) have provided the raw material to support true globalization of product development. This globalization in turn raises a strong need for members of an enterprise (design, manufacturing maintenance, sales, management) to exchange product information in a concurrent manner and collaborate throughout the life cycle of families of products. We summarize some of the key issues in computer supported cooperative work (CSCW) related to product development, and then cover some of our ongoing work in collaborative visualization and modeling. On visualization, we cover the collaborative aspects of: (a) geometry based rendering (3DIX) and (b) image based rendering (PanoramIX), and on modeling: (c) solid modeling (procedural solids, shape control), (d) real time reverse engineering (3D reconstruction), and (e) product data management (PM) View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Hardware implementation of shading models in an application specific integrated circuit

    Page(s): 150 - 159
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1660 KB)  

    The Truga001 is a single chip rendering processor with 12 embedded graphics functions. Phong and bump mapped shading, reflection and reflection mapping, gaseous object rendering and video mapping are incorporated fully in hardware with a MIMD structure. Shaded and texture mapped pixels are rendered at 3.8 ns/pixel which is equivalent to 1.2 million triangle polygons (100 pixels/s) with hidden surface removal. In the design of the Phong and bump mapped shading circuit, we used angular parameters for defining surface and light source normals instead of vector. This enables the circuit-scale less than 10000 gates/circuit. The chip is fabricated with a 940000 gate standard cell, 0.3 μm CMOS in a TCP/BGA package. The paper describes the hardware architecture and its implementation technologies of the Phong and bump mapped shading in an ASIC View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A multiple-view CAD representation for product modelling

    Page(s): 78 - 85
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1256 KB)  

    With the advent of concurrent engineering (CE), the engineering product design process has changed substantially. Different factors of the product life cycle, such as the manufacturing process, part assembly and quality control, can now all be simultaneously involved in the design phase. To achieve CE traditional computer-aided design systems are inadequate. Co-operative product design needs more powerful modelling techniques and geometric representation schemes than those offered by actual commercial CAD systems. A multiple-view CAD representation, called intermediate model, is presented. The intermediate model has been defined with the aim to upgrade a traditional CAD system to a feature-based modelling system which allows to represent different context dependent views of the product View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Spline interpolation with genetic algorithms

    Page(s): 47 - 54
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (696 KB)  

    A general framework is set up for the application of genetic algorithms in curve design. Then, within this scheme, the problem of spline interpolation-a frequently used method for representing complex geometrical shapes in CAD/CAM systems-is dealt with. While the method itself is simple and robust, it suffers from the drawback that some parameters must be given that are needed for the mathematical description but are not closely related to the geometrical input data of the object. The authors suggest taking a genetic approach to define the above parameters. The resulting curve minimizes a nonlinear functional which simulates the shape of an elastic bar View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Shape abstraction tools for modeling complex objects

    Page(s): 16 - 25
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1480 KB)  

    Shape is a very important way of perceiving and reasoning about the world. The authors introduce some considerations about shape representation and abstraction tools and their interaction with analysis and synthesis processes. A generic architecture for shape-based modelling is also outlined. The concepts discussed in the first part of the article are also exemplified through the description of some significant applications developed at the Istituto per la Matematica Applicata View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Context dependent extraction of volumetric features

    Page(s): 86 - 95, 244
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2260 KB)  

    As entities for describing products, features are commonly conceived as being of a semantically higher level than the purely geometric elements traditionally used in CAD systems. Thus, they constitute an effective means for the designer and process planner to consider objects in terms of entities that are meaningful for their activities. The greatest difficulty in using feature technology is the dependence of features on the specific context, i.e. features in one context may be meaningless in another. In this paper, a method for recognizing and deriving volumetric features from boundary representations is presented. The main advantage of this method is the possibility it provides for deriving different feature-based descriptions of the same part by considering the environment used and the degree of multiple interpretation required by the user View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Visual modeling of stomach growth on the basis of L-systems

    Page(s): 121 - 128
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (816 KB)  

    A parametric L-system (Lindenmayer system) is developed to model the growth and structure changes of human stomach over the time starting in the third week and going on into week four of human embryo development. The model takes into account what is known about embryo movement during growth. The framework uses the formalism of L-systems with constructs that are dependent on time and smooth growth functions. The method captures the development of human embryo stomach consistently with static observations of the real embryo. Computer animation and visual interpretation make it possible to understand the modeled processes accurately and lead to realistic exploration of the human stomach at various stages of development View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A unified surface smoothing scheme for automobile body shape modeling design

    Page(s): 198 - 203
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB)  

    A unified surface smoothing scheme is proposed to fit grid points, scatter points and boundary points, which are digitized from physical models with the Coordinate Measurement Machine, to smoothness parameter surfaces. A variety of curves and surfaces with different smoothness can be obtained with the aid of parameters such as approximation and smoothness weights, segment or patch numbers and the distribution of approximation and smoothness weights. A pickup car body is finished with the proposed method View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.