01618nas a2200241   4500000000100000000000100001008004100002260001200043653001000055653002400065653001600089653001600105653001100121653001500132100002000147700001500167700002100182245006800203856005200271300001200323490000600335520103500341       2016                            d  c05/201610acache10adaylight simulation10aMorton code10aout-of-core10apaging10aphoton map1 aRoland Schregle1 aLars Grobe1 aStephen Wittkopf00aAn out-of-core photon mapping approach to daylight coefficients  uhttp://dx.doi.org/10.1080/19401493.2016.1177116  a620-6320 v93 aClimate-based daylight modelling (CBDM) is an effective means of assessing the performance of daylight redirecting components (DRCs) with highly directional scattering to determine their impact on daylight availability and visual comfort. Such a simulation imposes significant computational demands on commodity hardware as it requires high density luminance samples obtained by forward raytracing. We propose an out-of-core photon mapping method within the Radiance framework to compute high quality daylight coefficients as a basis for CBDM. The method is particularly suited to angularly selective DRCs exhibiting strong redirection in conjunction with non-uniform sky luminance distributions with high resolution subdivisions. Our implementation is a work in progress and currently accommodates up to 4.3G photons on disk, while optimizing the in-core memory footprint by loading only photons which actually contribute flux to sensor points. We also leverage the fact that photon paths are independent through parallelization.