Real-Time Ray Traced Global Illumination using Fast Sphere Intersection Approximation for Dynamic Objects

• Main Author: Garmsen, Reed Phillip
• Format: Others
• Published: DigitalCommons@CalPoly 2019
• Subjects: Graphics and Human Computer Interfaces
• Online Access: https://digitalcommons.calpoly.edu/theses/1970; https://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=3383&context=theses

Realistic lighting models are an important component of modern computer generated, interactive 3D applications. One of the more difficult to emulate aspects of real-world lighting is the concept of indirect lighting, often referred to as global illumination in computer graphics. Balancing speed and accuracy requires carefully considered trade-offs to achieve plausible results and acceptable framerates. We present a novel technique of supporting global illumination within the constraints of the new DirectX Raytracing (DXR) API used with DirectX 12. By pre-computing spherical textures to approximate the diffuse color of dynamic objects, we build a smaller set of approximate geometry used for second bounce lighting calculations for diffuse light rays. This speeds up both the necessary intersection tests and the amount of geometry that needs to be updated within the GPU's acceleration structure. Our results show that our approach for diffuse bounced light is faster than using the conservative mesh for triangle-ray intersection in some cases. Since we are using this technique for diffuse bounced light the lower resolution of the spheres is close to the quality of traditional raytracing techniques for most materials.