Real-time ray transfer for lens flare rendering using sparse polynomials

Abstract While lens flares are often undesired artifacts of the imaging process, they are also essential for increasing the level of realism in video games and serve as a powerful artistic tool for photography and filmography. For these reasons, computationally reproducing lens flares has always received special attention. Due to the cost of analytical ray tracing, existing solutions are unable to simultaneously achieve the performance needed for real-time environments and retain the ability to simulate arbitrarily complex ghost shapes. Although polynomial optics has been successfully used to increase the efficiency of ray tracing in multiple rendering areas, no complete and validated solution exists that correctly models all aspects of lens flares. This paper presents our polynomial optics-based method for efficiently and accurately ray tracing lens flare ghosts. Our approach successfully models the shape, energy absorption, chromatic effects, and blocking of lens flare rays by partitioning the input domain into local fitting zones. We demonstrate that our model provides a considerable speedup and high accuracy compared to the analytical approach and achieves better fitting speed, output quality, and rendering performance than the naïve application of polynomial optics. The source code for our implementation is available on GitHub .