In movies, video games, virtual reality environments and other computer graphics areas, lighting is a major part of achieving accurate depictions of our physical world. Computing lighting that looks real remains complex and inefficient as the necessary consideration of all possible paths light can take remains too costly to be performed for every pixel in real time.
Computer scientists at Aalto University in Otaniemi, Finland, with expertise in video game development and lighting simulation algorithms, have developed a new computational method to address this challenge. Created by Ari Silvennoinen, a Ph.D. candidate in computer science and Jaakko Lehtinen, associate professor of computer science, the method allows real-time lighting simulations that are much faster and more accurate than existing methods.
The researchers focused on computing realistic indirect illumination from dynamic light sources on mostly static scenes. They also focus on demonstrating the accuracy of their algorithm on several scenes where the illumination in the environment consists of complicated patterns of light and shadow.
"Real-time dynamic global illumination remains a big challenge in the field. The challenge stems from the fact that, given a scene, any two points in the scene could be in interaction by participating in the light transport from one another," explained Silvennoinen. "The number of these interactions grows very rapidly. For example, with just 1,000 points, we have potentially 1,000,000 interactions."
The key novel contribution is a method that accurately computes indirect illumination using the information only from a sparse set of ‘radiance probes’ that allow real-time operation in 3D scenes of complexity on par with modern games.
"The quality of the results, in particular, the indirect shadows, is very high due to the accurate way we handle visibility between senders and receivers," said Silvennoinen. "Our method makes high-quality indirect illumination, the Holy Grail in real-time computer graphics, practically viable."
In the study, the researchers demonstrate their method on architectural illustrations, accurately showing how light through a window moves through a living room over the course of time or passes through shadowy columns of a dimly lit palace.
In addition to its direct application to game graphics, the researchers envision this method of enabling architects and their clients to see how their design works with dynamic illumination. Future work could allow lighting designers to have immediate feedback while placing virtual light sources in computationally restricted environments like virtual reality or augmented reality.
Silvennoinen and Lehtinen, who are also both researchers scientists at Remedy Entertainment and NVIDIA, respectively, will present their research at SIGGRAPH Asia 2017.