Feed-forward volume rendering algorithm for moderately parallel MIMD machines

Algorithms for direct volume rendering on parallel and vector processors are investigated. Volumes are transformed efficiently on parallel processors by dividing the data into slices and beams of voxels. Equal sized sets of slices along one axis are distributed to processors. Parallelism is achieved at two levels. Because each slice can be transformed independently of others, processors transform their assigned slices with no communication, thus providing maximum possible parallelism at the first level. Within each slice, consecutive beams are incrementally transformed using coherency in the transformation computation. Also, coherency across slices can be exploited to further enhance performance. This coherency yields the second level of parallelism through the use of the vector processing or pipelining. Other ongoing efforts include investigations into image reconstruction techniques, load balancing strategies, and improving performance

Classification and Survey of Algorithms for Volume Viewing

c s The task of the rendering process is to display the primitives used to represent the 3D volumetri cene onto a 2D screen. Rendering is composed of a viewing process which is the subject of this paper, b and the shading process. The projection process determines, for each screen pixel, which objects are seen y the sight ray cast from this pixel into the scene. The viewing algorithm is heavily dependent on the e e display primitives used to represent the volume and whether volume rendering or surface rendering ar mployed. Conventional viewing algorithms and graphics engines can be utilized to display geometric d primitives, typically employing surface rendering. However, when volume primitives are displayed irectly, a special volume viewing algorithm should be employed. This algorithm should capture the conp tents of the voxels on the surface as well as the inside of the volumetric object being visualized. This aper surveys and compares previous work in the field of direct volume vie..

Volume Rendering Polyhedral Grids by Incremental Slicing

Some important research results in science rely on the use various simulation techniques that operate in a space tessellates by a set of polyhedral cells. These cells which are part of an unstructured grid introduce exceptional problem with respect to data visualization. Volume rendering techniques which have been primarily developed to handle cartesian grids are painfully non-interactive when it comes to unstructured grids. We describe here an efficient method for rendering unstructured grids that is based on incremental slicing. For each view direction, the grid vertices are transformed to screen space using available graphics hardware. We then incrementally compute the 2D polygon-meshes that result from letting a set of equidistant planes, parallel to the screen plane, slice through our grid. Finally, the graphics hardware renders and composes these polygon-meshes in a front-to-back order. This algorithm can handle any grid made of arbitrary, possibly disconnected, convex polyhedra...

Realistic Display of Volumes

e o We present a method for recursively rendering a realistic image of a volumetric dataset consisting of a mixtur f sampled and synthetic objects. We describe several volume visualization tools that are based on the use of recurl w sive ray tracing. These include shadows, mirrors, specularity, and constructive solid geometry. We discuss severa ays to enhance our method both in terms of image quality and rendering speed by introducing the principles of adaptive traversal and probabilistic rendering. 1. INTRODUCTION - n A major goal in computer graphics has been the synthesis of photorealistic images using, among other tech iques, recursive ray tracing of geometric models. It is not obvious, however, that photorealism enhances the percep- - t tion of rendered sampled or computed datasets. Nevertheless, the need for enriching our set of visualization capabili ies for volumetric datasets in terms of rendering options has already been recognized. Levoy et al. [11] have used l r 'artistic ..

Template-Based Volume Viewing

We present an efficient three-phase algorithm for volume viewing that is based on exploit- - t ing coherency between rays in parallel projection. The algorithm starts by building a ray emplate and determining a special plane for projection -- the base-plane. Parallel rays are cast t into the volume from within the projected region of the volume on the base-plane, by repeating he sequence of steps specified in the ray-template. We carefully choose the type of line to be s employed and the way the template is being placed on the base-plane in order to assure uniform ampling of the volume by the discrete rays. We conclude by describing an optimized software K implementation of our algorithm and reporting its performance. eywords: volume rendering, ray casting, template, parallel projection 1. Introduction Volume visualization is the process of converting complex volume data to a format that is p amenable to human understanding while maintaining the integrity and accuracy of the data. Th..