This is a new technology, here’s a glimpse at what’s under the hood. Autodesk hopes to release additional validation studies and documentation as the tool matures.
How is it so fast?
First of all, the calculation happens on the cloud – not on your local machine. But, as importantly, the ray tracing algorithm is faster.
Autodesk 360 Rendering uses bidirectional ray tracing but with an additional intelligent algorithm to determine the ray order such that the most important rays are generated first. The result is a much faster convergence to final results. Revit’s RaaS engine calculates all the bounces that are important for making conclusions. Other tools follow the bounces of a photon even past the point where it practically affects the rendering. The algorithm Revit uses is called Multidimensional Lightcuts (Siggraph 2006), with trade secret/patented extensions.
Has it been validated?
The engine has been initially validated with the help of one of the top daylighting firms in the country. They used a consistent model to compare Revit’s360 Rendering illuminance simulation output to both Radiance (the industry standard lighting simulation tool) and to the actual space measured in the real world.
Results of the validation tests are strikingly similar in all ways but one…the time it takes to create the rendering. When we asked about the level of quality used in the Radiance rendering and how much time it took, the answer was: 5 bounces and it took about 4 hours to render. When we asked the cloud rendering technician how many bounces, the answer was ‘all of them’, and the rendering took about 10 minutes.