[Radiance-general] Luminaire modelling using Radiance

[Christopher Rush]

If you want to try Thomas’ recommendation, look in the IES file for a pair of lines just below the header that look like this. I’m borrowing the example out of Ian Ashdown’s “Thinking Photometrically Part II” which you can easily find online.
1 50000 1 5 3 1 1 .5 .6 0
1.0 1.0 495

In that example the 50000 represents number of lumens (now sometimes noted as -1 for LED luminaires tested differently), 495 represents number of Watts, and the values 0.5, 0.6, 0 represent the X, Y, and Z dimensions of a rectangular luminaire. In some cases, certain dimensional values could be given as negative, which signifies various types of rounded shapes for interpretation by software.

You can freely change the XYZ values in the IES file without affecting the data. Only when you import the IES file through IES2RAD (or into Dialux, AGI, etc.) does software interpret the dimensions and apply the brightness functions across the appropriate surface areas given by the dimensions.

-Chris



From: Thomas Bleicher [mailto:tbleicher at gmail.com]
Sent: Wednesday, November 11, 2015 8:47 PM
To: Radiance general discussion
Subject: Re: [Radiance-general] Luminaire modelling using Radiance

German

Have you tried to change the geometry identifier in the IES file to indicate a box geometry. I am a bit rusty on the specs but I don't think anything else depends on this information so the change should be simple to do. The transformation in a Radiance box is then done by ies2rad.

Regards,
Thomas

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