Computer Graphics: Granular Materials Help Make Sandcastle Images Faster (VIDEO)

First Posted: Sep 08, 2015 11:58 AM EDT

Computer graphics can be quite amazing when it comes to providing life-like images of numerous things.

A team of researchers at KIT, Disney Research and Cornell University have developed a process for efficient computation of photo-realistic images of granular materials for snow, salt, sand and sugar.

"Objects of granular media, such as a sandcastle, consist of millions or billions of grains. The computation time needed to produce photorealistic images amounts to hundreds to thousands of processor hours," Professor Carsten Dachsbacher of the Institute for Visualization and Data Analysis of KIT, said in a news release.

Materials like sand, salt or sugar that consist of randomly oriented grains visible at a closer look can be very difficult as paths of millions of light rays go through the grains and require simulation, researchers noted.

"In addition, complex scattering properties of the individual grains and arrangement of the grains in a system can prevent classical acceleration techniques from being used. This makes it difficult to find efficient algorithms," doctoral student Johannes Meng added. "In case of transparent grains and long light paths, computation time increases disproportionately."

Image synthesis can be rather difficult as it requires a new multi-scale process that adapts simulation to the structure of light transport in granular media on various scales. With just a few grains linked to each imaged, size, geometry and material properties of individual discernable grains, including the packing dentistry considered, researchers trace light rays through the virtual grains--otherwise referred to as path tracing. This computes light paths from each pixel back to the light sources. However, it cannot be applied to millions of grains.

The new process also automatically changes to another rendering technique in which volumetric path tracing is used following a few interactions that include reflections of grains provided that the contributions of individual interactions are no longer distinguished. Through a calculation of light scattering in materials, researchers demonstrated that this method normally can be applied to images of clouds or fog via a more accurate representation of light transport in granular materials and scales.

Lastly, the researchers revealed how the individual techniques have to be combined to produce consistent visual results through all scales--both on individual grains to objects made from billions of grains and in all images and animations.

Want to learn more about the method behind the making? Check out this video, courtesy of YouTube.