High-Quality Reflections, Refractions, and Caustics in Augmented Reality and their Contribution to Visual Coherence

In this paper we present a novel high-quality rendering system forAugmented Reality (AR). We study ray-tracing based renderingtechniques in AR with the goal of achieving real-time performanceand improving visual quality as well as visual coherence betweenreal and virtual objects in a final composited image. A number ofrealistic and physically correct rendering effects are demonstrated,that have not been presented in real-time AR environments before.Examples are high-quality specular effects such as caustics, refraction,reflection, together with a depth of field effect and antialiasing.We present a new GPU implementation of photon mapping andits application for the calculation of caustics in environments wherereal and virtual objects are combined. The composited image isproduced on-the-fly without the need of any preprocessing step. Amain contribution of our work is the achievement of interactive renderingspeed for high-quality ray-tracing algorithms in AR setups.Finally we performed an evaluation to study how users perceivevisual quality and visual coherence with different realistic renderingeffects. The results of our user study show that in 40.1% cases usersmistakenly judged virtual objects as real ones. Moreover we showthat high-quality rendering positively affects the perceived visualcoherence.