Real light is a complicated phenomenon that not only acts upon objects, but interacts with them–light bounces off an object and to another object so that an entire scene is implicated. In graphical applications, however, usually only one surface is lit without taking into consideration the other objects in the scene. Ray tracing is sometimes used in graphics to generate realistic lighting effects by tracing the path of light through a scene and the objects it would encounter. While this creates accurate and realistic lighting effects, this technique is so slow that it is not practical for real-time applications like video games or simulations.
To create real-time, real-looking lighting effects, graphics engineer Sean Petty and staff at the UM3D Lab have been experimenting with a publicly available and commonly used scene called Sponza to develop global illumination skill. The Sponza Atrium is a model of an actual building in Croatia with dramatic lighting. The lighting experiments in Sponza has helped the lab to develop a more realistic global illumination. Spherical harmonic (SH) lighting creates a realistic light rendering, using volumes to approximate how light should behave. While this method isn’t perfectly accurate in the way ray tracing is, algorithms are used to figure out which rays intersect objects and calculates the intensity of light going towards it, and emitting from it. This information is inserted into the 3D volume and overall virtual environment. These algorithms can then be applied in other scenes. Realistic lighting is vital to a user becoming psychologically immersed in a scene.