Abstract We propose a novel morphing algorithm for objects represented by point‐sampled geometry. The fundamental problem of point‐sampled geometry morphing is how to set the correspondence between points of the two objects which are usually of different size. The two objects are first parameterized by projecting the sample points onto a common parametric domain. As both objects are densely sampled, we present a novel accelerated parameterization algorithm employing the technique of LOD. The common parameter domain is then split recursively into clusters. The correspondence between sample points of the two objects is established by performing a local mapping in each cluster. As for complex geometries, the establishment of correspondence is facilitated by decomposing the geometry into patches using geodesic decomposition curves. To preserve the features during morphing, a process of features assignment is incorporated. By re‐sampling the in‐between object dynamically and adaptively, the cracks that would occasionally occur during morphing are successfully eliminated. Experiment results show that our algorithms are fast, stable and easy to implement. High‐quality morphing is produced. Copyright © 2004 John Wiley & Sons, Ltd.

Occlusion culling is an important technique to speed up the rendering process for walkthroughs in a complex environment. In this paper, we present a new approach for occlusion culling with respect to a view cell. A compact representation, the Global Occlusion Map (GOM), is proposed for storing the global visibility information of general 3D models with respect to the view cell. The GOM provides a collection of Directional Visibility Barriers (DVB), which are virtual occluding planes aligned with the main axes of the world coordinates that act as occluders to reject invisible objects lying behind them in every direction from a view cell. Since the GOM is a two-dimensional array, its size is bounded, depending only on the number of the sampled viewing directions. Furthermore, it is easy to conservatively compress the GOM by treating it as a depth image. Due to the axial orientations of the DVBs, both the computational and storage costs for occlusion culling based on the GOM is minimized. Our implementation shows the Global Occlusion Map is effective and efficient in urban walkthrough applications.

Pre-filtering is generally considered the ideal approach to antialiasing but is difficult to perform exactly for complex geometries such as curves or for arbitrary choice of filters. We present a discrete pre-filtering technique for anti-aliasing Bzier curves using arbitrary filters which is numerically and geometrically robust and whose accuracy is controllable. CR Categories and Subject Descriptors: I.3.3 [Computer Graphics]: Picture/Image Generation --- antialiasing Additional Keywords: Bzier curves, pre-filtering 1 INTRODUCTION The causes of aliasing in computer generated imagery are well known and may be broken down into two components: aliasing due to inadequate sampling of the ideal image and aliasing due to incorrect or inadequate reconstruction of the displayed image from the samples. Many techniques have been proposed but there is no ideal or universal solution and compromises have to be made. As Mitchell and Netravali [29] point out, graphics has generally avoided the is...

Whilst there has been considerable effort in constructing force feedback devices for use in virtual environments, and in the use of touch as a prosthesis for the blind, there has been little work on the use of touch in the visualisation or more properly, perceptualisation of data. Touch potentially offers an additional dimension of perception where visualisation is limited by screen size, resolution, and visual overload. We describe some tactile mice and experiments in using tactile mice for a variety of perceptualisation tasks.

This paper presents an analysis of progress in the use of sound as a tool in support of visualisation and gives an insight into its development and future needs. Special emphasis is given to the use of sound in scientific and engineering applications. A system developed to support surface data presentation and interaction by using sound is presented and discussed.

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introduction Free Access Share on Guest Editor's Introduction to Special Issue on Computational Geometry Author: Jurg Nievergelt View Profile Authors Info & Claims ACM Transactions on GraphicsVolume 3Issue 4pp 241–243https://doi.org/10.1145/357346.357347Published:01 October 1984Publication History 2citation393DownloadsMetricsTotal Citations2Total Downloads393Last 12 Months21Last 6 weeks1 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

Despite the relative sophistication of modern surface design systems, many graphical renderings of surfaces are rather crude. The paper discusses several possible renderings, including various line drawings methods, realistic and functional shading, and combinations of line drawings and smooth shading. It concludes that a good choice is the superposition of contours or sections on either realistic or Gaussian curvature shading.

Whereas, historically, much of the effort on computer-aided geometric design has concentrated on the problems of representing so-called sculptured surfaces, there has recently been much interest in systems which can handle typical mechanical components by a volume modelling approach. The paper is concerned with the possibility of combining the two approaches and discusses the issues raised. A solution in terms of applying smoothing operators to a geometric coarse structure is proposed, with the added benefits of detecting and successfully handling anomalous regions in surfaces and leading to potential benefits in the analysis of geometric properties.

One of the main problems in computer-aided design is how to input shape information to the computer. The paper describes a method developed for the interactive interpolation and approximation of curves which has been found in practice to provide a natural interface between the mathematically unsophisticated user and the computer.