[Radiance-general] getting irradiance from source defined inphotometric units

[Guglielmetti, Robert]

Hi Thomas,

Two words: "my bad". You are absolutely correct; if left to its own devices, ies2rad will scan the header lines for a lamp type and look for a match in the lamp.tab. Sorry about that! I guess I forgot about that option because it seemed so random I never understood why anyone would want to leave it up to such a potentially unreliable method, and have defaulted to using the -t option to explicitly specify my lamp types. Indeed, Greg notes in the manpage, regarding the whole [LAMP] header:

"This method of assigning colors to fixtures is less than perfect, and the IES would do  well to  include  explicit  spectral information somehow in their specification."

In any event, I apologize for the mis-information. If you ask me, I feel like this is one more reason to always use the -t option.


________________________________
From: Thomas Bleicher <tbleicher at googlemail.com>
Reply-To: Radiance general discussion <radiance-general at radiance-online.org>
Date: Mon, 12 Oct 2009 02:36:48 -0600
To: Radiance general discussion <radiance-general at radiance-online.org>
Subject: Re: [Radiance-general] getting irradiance from source defined  inphotometric units

Hi Rob.

On Sun, Oct 11, 2009 at 7:15 PM, Guglielmetti, Robert
<Robert.Guglielmetti at nrel.gov> wrote:
> Hi Lars,
>
> I'm a little hazy on a couple of your questions. When you say "used a WHITE keyword in your IES", do you mean using the "-t white" option in your ies2rad command, or actually adding a keyword to the ies file? Because ies2rad ignores the keywords in the ies file

That's not quite correct. ies2rad looks at the [LAMP] entry and
tries to match an entry in lamp.tab to the string found. Mostly
that doesn't work because there is no standard in naming lamp
sources. The few matches I remember were accidental.

It's better to specify the lamp type on the command line even
if you're not actually interested in the light color. I even thought
about patching ies2rad to make the WHITE type the default and
skip the lookup altogether. That would garantee a predictable
conversion.

Regards,
Thomas

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