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Showing papers by "Charles R. Dyer published in 1994"


Journal ArticleDOI
TL;DR: Two interactive systems developed at the University of Wisconsin-Madison Space Science and Engineering Center that provide visualization packages that help scientists see the internal workings of their algorithms and thus understand their computations are described.
Abstract: Scientists often view computer algorithms as risk-filled black boxes. The barrier between scientists and their computations can be bridged by techniques that make the internal workings of algorithms visible and that allow scientists to experiment with their computations. We describe two interactive systems developed at the University of Wisconsin-Madison Space Science and Engineering Center (SSEC) that provide these capabilities to Earth and space scientists. These visualization packages help scientists see the internal workings of their algorithms and thus understand their computations. >

70 citations


Journal ArticleDOI
TL;DR: In this article, an approach for recovering surface shape from the occluding contour using an active (i.e., moving) observer is presented. But this approach does not require knowledge of the velocities or accelerations of the observer.
Abstract: We present an approach for recovering surface shape from the occluding contour using an active (i.e., moving) observer. It is based on a relation between the geometries of a surface in a scene and its occluding contour: If the viewing direction of the observer is along a principal direction for a surface point whose projection is on the contour, surface shape (i.e., curvature) at the surface point can be recovered from the contour. Unlike previous approaches for recovering shape from the occluding contour, we use an observer thatpurposefully changes viewpoint in order to achieve a well-defined geometric relationship with respect to a 3-D shape prior to its recognition. We show that there is a simple and efficient viewing strategy that allows the observer to align the viewing direction with one of the two principal directions for a point on the surface. This strategy depends on only curvature measurements on the occluding contour and therefore demonstrates that recovering quantitative shape information from the contour does not require knowledge of the velocities or accelerations of the observer. Experimental results demonstrate that our method can be easily implemented and can provide reliable shape information from the occluding contour.

66 citations


Proceedings Article
01 Jan 1994
TL;DR: In this article, an approach for identifying the occludin,p contour and determining its sidedness using an active observer is presented, which is bused on the non-stationarity property of the visible rim.
Abstract: We present an approach for identifying the occludin,p contour and determining its sidedness using an active (i.e., moving) observel: It is bused on the non-stationarity property of the visible rim: When the observer’s viewpoint is changed, the visible rim is a collection of curves that “slide,” rigidly or non-rigidly, over the surface. We show that the observer can deterministically choose three views on the tangent plane of selected sulface points to distinguish such curves from stationary surface curves (i.e., surface markings). Our approach demonstrates that the occluding con tour can be identijed directly, i.e., withoutjrst computing surface shape (distance and curvature).

45 citations


Proceedings ArticleDOI
08 May 1994
TL;DR: An approach for exploring an unknown, arbitrary surface in three-dimensional (3D) space by a mobile robot and two provably-correct exploration strategies that exploit these trade-offs and use visual sensors to plan the robot's motion.
Abstract: An approach is presented for exploring an unknown, arbitrary surface in three-dimensional (3D) space by a mobile robot. The main contributions are (1) an analysis of the capabilities a robot must possess and the trade-offs involved in the design of an exploration strategy, and (2) two provably-correct exploration strategies that exploit these trade-offs and use visual sensors (e.g., cameras and range sensors) to plan the robot's motion. No such analysis existed previously for the case of a robot moving freely in 3D space. The approach exploits the notion of the occlusion boundary, i.e., the points separating the visible from the occluded parts of an object. The occlusion boundary is a collection of curves that "slide" over the surface when the robot's position is continuously controlled, inducing the visibility of surface points over which they slide. The paths generated by our strategies force the occlusion boundary to slide over the entire surface. The strategies provide a basis for integrating motion planning and visual sensing under a common computational framework. >

45 citations


Proceedings ArticleDOI
17 Oct 1994
TL;DR: These lattice models give a way to quantize the information content of data and displays and to define conditions on the visualization mappings from data to displays if and only if they are lattice isomorphisms.
Abstract: In order to develop a foundation for visualization, we develop lattice models for data objects and displays that focus on the fact that data objects are approximations to mathematical objects and real displays are approximations to ideal displays. These lattice models give us a way to quantize the information content of data and displays and to define conditions on the visualization mappings from data to displays. Mappings satisfy these conditions if and only if they are lattice isomorphisms. We show how to apply this result to scientific data and display models, and discuss how it might be applied to recursively defined data types appropriate for complex information processing. >

37 citations


Proceedings ArticleDOI
11 Nov 1994
TL;DR: In this paper, a generalization of period is defined for cyclic motions that makes periodic variation explicit, and several purely temporal motion features are derived, relating to the nature and location of irregularities.
Abstract: Real cyclic motions tend not to be perfectly even, i.e., the period varies slightly from one cycle to the next, because of physically important changes in the scene. A generalization of period is defined for cyclic motions that makes periodic variation explicit. This representation, called the period trace, is compact and purely temporal, describing the evolution of an object or scene without reference to spatial quantities such as position or velocity. By delimiting cycles and identifying correspondences across cycles, the period trace provides a means of temporally registering a cyclic motion. In addition, several purely temporal motion features are derived, relating to the nature and location of irregularities. Results are presented using real image sequences and applications to athletic and medical motion analysis are discussed. >

12 citations


Proceedings ArticleDOI
08 Feb 1994
TL;DR: An approach for recovering a global surface model of an object from the deformation of the occluding contour using an active (i.e., mobile) observer able to control its motion using a calibrated trinocular camera rig and a mechanism for controlling the relative position and orientation of the viewed surface with respect to thetrinocular rig.
Abstract: Presents an approach for recovering a global surface model of an object from the deformation of the occluding contour using an active (i.e., mobile) observer able to control its motion. In particular, the authors consider two problems: (1) How can the observer's viewpoint be controlled in order to generate a dense sequence of images that allows incremental reconstruction of an unknown surface, and (2) how can one construct a global surface model from the generated image sequence? Solving these two problems is crucial for automatically constructing models of objects whose surface is non-convex and self-occludes. They achieve the first goal by purposefully and qualitatively controlling the observer's instantaneous direction of motion in order to control the motion of the visible rim over the surface. They achieve the second goal by using a calibrated trinocular camera rig and a mechanism for controlling the relative position and orientation of the viewed surface with respect to the trinocular rig. >

9 citations