A progressive refinement approach for the visualisation of implicit surfaces

Visualising implicit surfaces with the ray casting method is a slow procedure. The design cycle of a new implicit surface is, therefore, fraught with long latency times as a user must wait for the surface to be rendered before being able to decide what changes should be introduced in the next iteration. In this paper, we present an attempt at reducing the design cycle of an implicit surface modeler by introducing a progressive refinement rendering approach to the visualisation of implicit surfaces. This progressive refinement renderer provides a quick previewing facility. It first displays a low quality estimate of what the final rendering is going to be and, as the computation progresses, increases the quality of this estimate at a steady rate. The progressive refinement algorithm is based on the adaptive subdivision of the viewing frustrum into smaller cells. An estimate for the variation of the implicit function inside each cell is obtained with an affine arithmetic range estimation technique. Overall, we show that our progressive refinement approach not only provides the user with visual feedback as the rendering advances but is also capable of completing the image faster than a conventional implicit surface rendering algorithm based on ray casting

Splitting Set-Theoretic Solid Models into Connected Components

A major problem with volume modelling systems is that processing times may increase with model complexity in a worse than linear fashion. The authors have addressed this problem, for picture generation, by repeatedly dividing the space occupied by a model, and evaluating the sub-models created only when they meet a criterion of simplicity. Hidden surface elimination has been integrated with evaluation, in such a way that major portions of the model which are not visible are never evaluated. An example demonstrates a better than linear relationship between model complexity and computation time, and also shows the effect of picture complexity on the performance of the proces

Eliminating Redundant Primitives from Set- Theoretic Solid Models by a Consideration of Constituents

Set-theoretic solid models often contain redundant primitives, which slow down rendering and other processes. They are not simple to remove, especially as there can be alternative eliminations that may not be equally desirable. There has been recent progress towards solving this problem, but existing techniques for eliminating such redundant primitives do not fully consider the possibilities and rely on repeated evaluation of parts of the object's boundary, a process that is likely to be very slow. This article proposes a technique that allows alternative eliminations to be examined, and outlines a potentially efficient, but geometrically approximate, method of implementatio

Shape Models in Computer-Integrated Manufacture: a Review

Existing computer-aided manufacturing systems are based on models of shape tailored to a particular process. Computer- integrated manufacture involves many different processes, and hence requires more complete models of components or assemblies. This can be provided by solid modelling techniques extended to include extra data related to manufacture such as form features and tolerances. These developments are being applied to many manufacturing processes, from casting to assembly, but profound questions remain concerning both the structure and the use of shape models in manufactur

Three-Dimensional Models for Computer Graphics

The various object models which are in use for generating computer graphics are reviewed and some of their advantages and disadvantages discussed. In particular, methods of overcoming the apparently unpromising performance characteristics of set-theoretic solid models are described. A number of examples are given showing the use of set-theoretic models in graphics applications. It is concluded that, while these models were developed for computer-aided design, they will have increasing use in computer graphic

Generalizing Active Zones for Set-Theoretic Solid Models

A major drawback of the set-theoretic solid model is the global and non-unique way in which it is defined. In a recent paper, Rossignac and Voelcker introduced the concept of the active zone of a primitive or sub-model, which provides a localization of a set-theoretic model which is useful for a number of purposes. A more general, but simplified, definition of the active zone is presented which exploits the properties of the symmetric difference operator. A novel application of the active zone to the interactive graphical editing of set- theoretic solid models is also outline

Splitting set-theoretic solid models into connected components

SIGLEAvailable from British Library Document Supply Centre- DSC:4360.105(UKSC--210) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Generalizing active zones for set-theoretic solid models

SIGLEAvailable from British Library Document Supply Centre- DSC:4360.105(UKSC--182) / BLDSC - British Library Document Supply CentreGBUnited Kingdo