Ray tracing (graphics)

About: Ray tracing (graphics) is a research topic. Over the lifetime, 7010 publications have been published within this topic receiving 112500 citations. The topic is also known as: RT.

Angle-domain common-image gathers by wavefield continuation methods

Abstract: Migration in the angle domain creates seismic images for different reflection angles. We present a method for computing angle-domain common-image gathers from seismic images obtained by depth migration using wavefield continuation. Our method operates on prestack migrated images and produces the output as a function of the reflection angle, not as a function of offset ray parameter as in other alternative approaches. The method amounts to a radial-trace transform in the Fourier domain and is equivalent to a slant stack in the space domain. We obtain the angle gathers using a stretch technique that enables us to impose smoothness through regularization. Several examples show that our method is accurate, fast, robust, and easy to implement. The main anticipated applications of our method are in the areas of migration-velocity analysis and amplitude-versus-angle analysis.

A rendering algorithm for visualizing 3D scalar fields

Abstract: This paper presents a ray tracing algorithm for rendering 3D scalar fields. An illumination model is developed in which the field is characterized as a varying density emittter with a single level of scattering. This model is equivalent to a particle system in which the particles are sufficiently small. Along each ray cast from the eye, the field is expressed as a function of the ray parameter. The algorithm computes properties of the field along the ray such as the attenuated intensity, the peak density, and the center of gravity, etc., These are mapped into HSV color space to produce an image for visualization.Images produced in this manner are perceived as a varying density 'cloud' where color highlights the computed attributes. The application of this technique is demonstrated for visualizing a three dimensional seismic data set.

Generalization of Lambert's reflectance model

Abstract: Lambert's model for body reflection is widely used in computer graphics. It is used extensively by rendering techniques such as radiosity and ray tracing. For several real-world objects, however, Lambert's model can prove to be a very inaccurate approximation to the body reflectance. While the brightness of a Lambertian surface is independent of viewing direction, that of a rough surface increases as the viewing direction approaches the light source direction. In this paper, a comprehensive model is developed that predicts body reflectance from rough surfaces. The surface is modeled as a collection of Lambertian facets. It is shown that such a surface is inherently non-Lambertian due to the foreshortening of the surface facets. Further, the model accounts for complex geometric and radiometric phenomena such as masking, shadowing, and interreflections between facets. Several experiments have been conducted on samples of rough diffuse surfaces, such as, plaster, sand, clay, and cloth. All these surface demonstrate significant deviation from Lambertian behavior. The reflectance measurements obtained are in strong agreement with the reflectance predicted by the model.