"Candelas Lumens and Lux" introduction to lighting  terms and calculations
"Candelas Lumens and Lux" introduction to lighting  terms and calculations




How to convert from IESNA Type B to IESNA TypeC

An IESNA Type B photometry is a VH measured photometry, mainly used for floodlights etc. An IESNA Type C photometry is a C-Gamma photometry, usually used for internal lighting and roads.

Sometimes you get a Type B file and need to convert it to a Type C, maybe for rendering software. For example the Indigo Renderer only supports Type C IES files.

Joe Heaton has found out the quickest way of using PhotoView (the free open version) to do the convertion in three steps.

Step 1) Open the Type B file in PhotoView. You'll see it is type B because it is in the VH branch of the tree list of photometries:


Step 2) Save the file as an LDT file:

Saving a photometry as LDTt.

Step 3) Close the file and then reopen the just saved LDT, it will appear in the CG branch:

CG Iensa File

Step 4) Save this file as an IESNA file and it will be a Type C IESNA. (OK, I lied, there are 4 steps)

For more information on what VH and CG mean (and lots of other interesting lighting facts) you could read this book, Candelas Lumens and Lux:

VH and CG explained



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