Manzi, MarcoKettunen, MarkusAittala, MiikaLehtinen, JaakkoDurand, FrédoZwicker, MatthiasJaakko Lehtinen and Derek Nowrouzezahrai2015-06-232015-06-232015https://doi.org/10.2312/sre.20151168Gradient-domain path tracing has recently been introduced as an efficient realistic image synthesis algorithm. This paper introduces a bidirectional gradient-domain sampler that outperforms traditional bidirectional path tracing often by a factor of two to five in terms of squared error at equal render time. It also improves over unidirectional gradient-domain path tracing in challenging visibility conditions, similarly to how conventional bidirectional path tracing improves over its unidirectional counterpart. Our algorithm leverages a novel multiple importance sampling technique and an efficient implementation of a high-quality shift mapping suitable for bidirectional path tracing. We demonstrate the versatility of our approach in several challenging light transport scenarios.I.3.3 [Computer Graphics]Picture/Image GenerationLine and curve generation10.2312/sre.2015116865-74