A comparison of the quality of light distribution in different diamond models

Abstract

We created visualizations to show both single photons traveling through the scene and many photons in a single scene. Different colors were used to differentiate photon wavelengths or to show the number of bounces a photon had taken along its path. Small normal lines were used to show when the photons had hit a diamond face or a wall, which was useful both for debugging purposes on individual hits and when looking at the distribution of many photon hits in a scene. In order to be able to view more photon paths in a scene without them blocking each other, We also created visualizations with low alpha photon paths.

We found that the two round brilliant diamond models we used performed significantly better than the other types of models at sending photons out of the top half of the model. The princess cut model also did much better than the sphere, which was used as an example of how much light would be sent out of the top if no effort went into designing a diamond to send light out of the top. We used the angle at which the photons leave the diamond and the angle of the faces that they leave from to determine which diamond models perform the best.

We used forward raytracing to recursively send photons through a scene con- taining a diamond. The Sellmeier equation was used to determine if a photon was absorbed, and then the Fresnel equation determined if the photon was reflected or refracted. If the photon reflected, we used the reflection equation, and if it refracted, we used Snell’s Law to determine the refraction angle.

In this thesis, we explore the way different cuts of diamonds affect the light that interacts with them. While some have analyzed diamond shape mathematically, no currently published research has used simulation to determine how light interacts with diamond models. We used forward ray tracing to simulate photons traveling through the scene using reflection and refraction.