ISSN:1049-8907    

DOI:10.1002/vis.4340040102

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractScientific visualization is proving very promising for the study of biological interactions at the organismal level in porous opaque media. We present our research in visualizing and modelling fungal and plant root development and interactions in the soil. Because the dynamic biological properties of the soil ecosystem can be observed in only the crudest fashion, we emphasize the fundamental link between visualization and modelling. Our research focuses along the parallel lines of imaging actual phenomena and of modelling these same phenomena. Many soil organisms, such as plants and fungi, exist predominately in a vegetative state which is highly branched, non‐random and non‐homogeneous. This structure itself is important to dynamic process such as parasitism of one organism by another, yet due to the opacity of soil, structure is difficult to observe and dynamic interactions are impossible to observe. The modelling of growth patterns and interactions of fungi and plant roots with the concomitant use of visualization and rigorous model validation provides the best method to build a working concept, which is faithful to the spatial organization of the real world. We hypothesize that the genetic determinants controlling growth and interactions operate both inside and outside the soil environment. We conclude that visualization provides a means by which spatial extrapolation of laboratory observations may be made to the real world, providing both model validation and a means to build mechanistically‐based hypotheses about different types of dynamic phenomena in the soil ecosystem, which can be tested in the

ISSN:1049-8907    

DOI:10.1002/vis.4340040103

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe Graphics and Video Laboratory of the Naval Postgraduate School (NPS) is in the process of constructing a three dimensional (3D) virtual world called NPSNET.1NPSNET is a low‐cost, commercial workstation‐based 3D visual simulator that uses SIMNET terrain databases and networking.2NPSNET is programmed using off‐the‐shelf SGI IRIS graphics workstations, rather than the platform‐specific nodes of SIMNET. Part of the work in constructing the NPSNET world is detecting and resolving collisions in real‐time. Such collision detection and resolution has been accomplished and integrated into the latest version of NPSNET, NPSNET‐2. The detection of vehicle‐weapon, vehicle‐vehicle and vehicle‐stationary non‐vehicle collisions is performed through

ISSN:1049-8907    

DOI:10.1002/vis.4340040104

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractIn this paper we present a method to calculate the rolling of a rigid convex object on a smooth biparametric surface where a single contact point is maintained during the animation. The object's motion is computed using a prediction‐correction schema. The prediction computes the motion of the object rolling on the tangent plane at the current contact point. The next contact point is obtained byprojectingthe predicted point onto the curved surface. A correction is made according to the local surface curvature. An algorithm which calculates the initial contact point between the surface and the object is given. The rolling of a ball is presented as an exampl

ISSN:1049-8907    

DOI:10.1002/vis.4340040105

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA three‐dimensional surface is a useful graphic representation of a two‐dimensional function which has been sampled on a regular grid. Shading the surface to simulate the effects of direct lighting makes visible small changes in the surface orientation, and enhances realism when the data represents a physical surface such as terrain. Shading interpolation calculations and surface patch generation techniques require the specification of a surface normal vector (or related slope information) at each sample point. These normal vectors are usually generated by averaging local data such as the normal vectors of the surfaces of a triangular mesh connecting the points. This paper describes a technique which uses Fourier filtering to generate normal vectors for two‐dimensional sampled data. Images and analysis of frequency spectra are included to show how this technique preserves detail which is lost using the averaging method. Performance figures show that this enhancement of detail in the final image can be achieved for only a small increase in computation

ISSN:1049-8907    

DOI:10.1002/vis.4340040106

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThesame origin ray set (SORS)is a computational primitive which can be used by ray tracing, radiosity and multiple pass illumination simulation algorithms for realistic image synthesis. A SORS consists of a set of rays emanating from the same point in space. TheSORS querycomputes the first object intersected by each ray and the intersection point. In this paper we present an efficientprojection algorithmfor computing a SORS query for polygonal scenes. The algorithm achieves its efficiency by separating ray‐polygon intersection detection from the computation of the intersection point between the ray and the polygon's plane. The algorithm can be integrated with all current illumination acceleration schemes. We analyse the projection algorithm and compare it to the alternative of computing the SORS query one ray at a time. The analysis' results are expressed in terms of a few intuitive parameters, measuring the success of the acceleration scheme in culling irrelevant objects and the concentration of the ray set. The projection algorithm can be up to five times more efficient, depending on these parameters and the quality of the image. The relative advantage of the projection increases with image qualit

ISSN:1049-8907    

DOI:10.1002/vis.4340040107

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:1049-8907    

DOI:10.1002/vis.4340040108

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:1049-8907    

DOI:10.1002/vis.4340040101

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY