Image Generation via Radiance

TDG is developing an interactive website – www.EcoAdvisor.com -- intended to provide guidance on daylighting design for buildings. One objective of this website is to demonstrate how daylighting design can improve the visual quality of spaces in buildings. To achieve this objective, we are now using the Radiance software program to generate many images of typical office spaces.

Radiance is quite good at developing reasonably accurate images of spaces that incorporate both daylighting and electric lighting. However, it has been developed via a research effort at a national laboratory and is not a commercial production tool. Indeed, it is quite difficult to use, and often obliquely documented. Also, the most flexible version of it runs under Linux but not Windows. Thus, we have set up a major Linux-based system for using Radiance.

TDG’s Computer Farm: We have developed a comprehensive in-house hardware and software processing system that enables us to use Radiance in an hands-off production batch mode. The TDG processing system for Radiance makes extensive use of Linux scripts developed in-house to permit multiple processors and computers to share image generation activities. We currently have 7 processors on dual-boot systems (Linux and Windows) that can be used for this process, and are planning to add a few more processors.

Generating Multiple Radiance Images via Linux Scripts: We have developed a comprehensive set of Linux scripts for generating multiple Radiance images. Since a detailed Radiance image can take 1-3 days to process on a single processor, having an automated process is critical since developing a multiple set of images might take several weeks to complete. In general the scripts control the following sequence activities:

§         A set of parametric images is defined with variables set in a text file extracted from an Excel file.

§         A Linux script allocates all images to available processors.

§         As each processor generates Radiance images, a Linux script “harvests” them by moving the files to a large hard-drive on a single workstation.

§         After all processing is completed then the Radiance images undergo appropriate post-processing.

§         Then, since most images are destined for web use, the output files are converted to JPG format.

§         Finally, the files are moved to the TDG server until they are uploaded to the appropriate website location.

We have developed file-naming protocols to track the large volume of input and output files that are associated with the generated images.

EcoAdvisor
Radiance Generation
Online Multimedia
EnergyPlus Tools
DOE-2 Param

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