Rendering light fields for optical system simulation

Abstract

The light field describes the radiance at a given point provided by a ray coming from a particular direction. Integrating the light field for all possible rays passing through that point gives total irradiance. For a static scene, the light field is unique. Cameras act as integrators of the light field. Previously, it was demonstrated that freeware rendering software can be used to simulate the light field entering an arbitrary camera lens. This is accomplished by placing an array of ideal pinhole cameras at the entrance pupil location and rendering. The pinhole camera images encode the ray directions for rays passing through the pinholes. The set of images from this array then describes the light field. Images for real camera lenses with different types of aberrations are then simulated directly from the light field. The advantage of this technique is that the light field only needs to be calculated once for a given scene. Calculation of the light field is computationally expensive and the practicality of implementing high resolution light field simulations on a desktop computer is limited. However, cloud-based rendering services with arrays of CPUs and GPUs are now readily available and affordable. These services enable more realistic simulations and different scenes to be rapidly created. Here, the techniques are demonstrated for different real lens aberration forms.