Real-Time Dynamic Mirage Rendering

Abstract

Mirages are a visual phenomenon consisting of the appearance of a mirrored image of an object, without the presence of an actual mirror surface, due to light rays that are curved because of continuous refraction in the air, which relates to differences between the surface and ambient temperature.
As temperature is defined in space, while a typical standard rasterization pipeline only processes surfaces, these phenomena are difficult to reproduce.
Approximating the nonlinear ray path with ray marching becomes taxing due to the long light paths.
Current approaches use acceleration structures and have not been implemented in a rasterizer.

We present two methods that make dynamic real-time rendering of mirages possible, which fit well in the rasterization pipeline.
The first solution uses a second camera to capture surface temperature and normal information below the view ray, and approximates the nonlinear path of the ray in as few steps as possible.
The second method obtains the surface information in screen space instead, making it faster, but potentially less accurate in heterogeneous scenes.

Results show that both methods are capable of rendering mirages dynamically and in real-time when the surface is relatively flat.
Therefore, both methods, especially the second, faster method, could be used for the rendering of mirages on relatively flat faces, enabling real-time dynamic rendering of mirages in video games on those types of surfaces.