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Ambient resolution setting

asked 2017-04-26 13:43:45 -0500

Determinant gravatar image

updated 2017-04-26 13:46:43 -0500

What is the default ambient resolution setting for OS/Radiance? Can I change this?

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answered 2017-04-26 16:20:16 -0500

updated 2017-04-26 17:29:37 -0500

Congratulations @Determinant, you've drawn me out of my medical leave hibernation. You've also exposed a rather lame missing element from the Radiance settings dialog in the OpenStudio app...

It appears I've omitted -ar (ambient resolution) from the list of user-specifiable Radiance parameters in the OS app's simulation settings tab.(!) What this means is the default value for -ar is whatever default is on your system, and that no, you cannot change the value for -ar on an OpenStudio model/project basis when using the OpenStudio Radiance measure. The default was raised a while back at least, to a reasonable value of -ar 256. Recent versions of OpenStudio ship with Radiance, and will, in fact, use this value as the default. So, there's that. ¯_(ツ)_/¯

@GregWard, is there a way to change a default value of a radiance program(s)'s options without re-compiling? This may be a way for you to coerce Radiance to do what you want ahead of you running a specific OpenStudio workflow, @Determinant. But unfortunately, there isn't an easy way to add -ar to the list of user-specifiable Radiance parameters in the app (which is the vector for them to the measure at this point in time).

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Thanks for the info. I need -ar of at least 60 per LightLouver recommendations, so I think I'm good. Talking to our old co-worker (ZR) about other params. Thought maybe I could sneak a hardcoded -ar into the rfluxmtx command but guess not. You have any LightLouver Radiance param recommendations? Hope your shoulder's doing well!!

Determinant gravatar image Determinant  ( 2017-04-26 17:37:45 -0500 )edit

If you were to hard-code a different default value, this would be overridden by the first -ar option on the command line. Subsequent settings of -ar will in turn override the earlier ones. This is a general mechanism for having default (and other) parameters overridden. The "rad" program offers a general "render" setting for any parameters the user wishes to specify, which will be tacked on after the other settings "rad" has made. It would be nice to offer a general string in OpenStudio for a similar purpose.

GregWard gravatar image GregWard  ( 2017-04-26 17:56:46 -0500 )edit

OS has a general setting like this, but the underlying mechanism to translate those general choices to specific Radiance program options is missing some teeth.

rpg777 gravatar image rpg777  ( 2017-04-26 18:36:40 -0500 )edit

Eric, if you are using the "light redirecting louver" option in OS when you add the shading device, you are getting a BSDF for Lightlouver. This Klems basis BSDF will give you reasonable results with the default settings, for numeric analysis of illuminance. It is not reliable for glare evaluations because of the low resolution of the BSDF.

rpg777 gravatar image rpg777  ( 2017-04-26 18:39:37 -0500 )edit

I'm using the BSDF from LightLouver's website which I think is comparable if not equal. Savings are low though which is why I'm talking to ZR. In addition to the ambient params, maybe need to increase the clerestory height and decrease the head height per your NREL RFS study.

Determinant gravatar image Determinant  ( 2017-04-26 19:03:15 -0500 )edit

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Asked: 2017-04-26 13:43:45 -0500

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Last updated: Apr 26 '17