Announcing the RADIANCE out-of-core photon map

Dear RADIANCE community,

we are proud to announce the release of a heavily revised RADIANCE photon map which includes parallelisation and out-of-core storage. This is the final outcome of the software developed during our project at the Competence Centre Envelopes and Solar Energy at the Lucerne University of Applied Sciences and Arts.

The out-of-core photon map enables simulations with very large numbers of photons on commodity hardware using on-demand loading and caching techniques. This is particularly useful with annual simulations using rcontrib, where the number of required photons scales linearly with the number of timestamps.

Since we consider out-of-core storage an advanced option, it must be explicitly enabled during compilation of the RADIANCE software; currently the original in-core photon map is still the default. Details on building the out-of-core photon map from source are documented in the RADIANCE distribution under ray/doc/notes compile_switches. Irrespective of the storage option used, mkpmap is now parallelised and accepts the '-n' option.

The software is now available from the RADIANCE CVS repository and will be included in the next official release. We provide this software to the community as is, with the caveat that it is not actively supported; I can volunteer limited support in my free time when possible, particularly in response to reported bugs.

The out-of-core photon map is documented in a paper in the Journal of Building Performance Simulation, and in an online technical report:

This work was supported by the Swiss National Science Foundation as part of the project ‘Simulation-based assessment of daylight redirecting components for energy savings in office buildings’ under grant SNSF #147053.

Best regards and happy photon mapping,



Dr. Roland Schregle
Senior Research Associate

Lucerne University of Applied Sciences and Arts
School of Engineering and Architecture
CC Envelopes and Solar Energy (EASE)