Ray-transfer functions for camera simulation of 3D scenes with hidden lens design

TL;DR

This paper introduces a method to simulate camera optics using black box lens models from Zemax, enabling accurate ray tracing in physically based rendering without revealing proprietary lens designs.

Contribution

It presents a polynomial ray transfer function derived from Zemax models and integrates it into PBRT for realistic camera simulation while preserving lens confidentiality.

Findings

Ray transfer functions match Zemax calculations for edge spread functions.

The method enables accurate, confidential optical simulations in physically based rendering.

Software implementation facilitates practical adoption in imaging system design.

Abstract

Combining image sensor simulation tools (e.g., ISETCam) with physically based ray tracing (e.g., PBRT) offers possibilities for designing and evaluating novel imaging systems as well as for synthesizing physically accurate, labeled images for machine learning. One practical limitation has been simulating the optics precisely: Lens manufacturers generally prefer to keep lens design confidential. We present a pragmatic solution to this problem using a black box lens model in Zemax; such models provide necessary optical information while preserving the lens designer's intellectual property. First, we describe and provide software to construct a polynomial ray transfer function that characterizes how rays entering the lens at any position and angle subsequently exit the lens. We implement the ray-transfer calculation as a camera model in PBRT and confirm that the PBRT ray-transfer calculations match the Zemax lens calculations for edge spread functions and relative illumination.