[Radiance-general] Re: direct/indirect photometric
Charles Ehrlich
[email protected]
Tue, 27 May 2003 09:43:33 -0700 (PDT)
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Greg and John An, Unless the new version of Radiance is significantly different that when I wrote chapter 5, I do not think that you need to change A1 if you follow the method described in the book. The method was specifically designed to address linear sources. It is also the method employed in the luminaire editor in Desktop Radiance. Is it still true that the "lboxcorr" function automatically corrects for the surface area of the emitter? If not, then we have a major re-write on our hands for the new edition. -Chas
[email protected] wrote:
Date: Mon, 26 May 2003 09:02:47 -0700
Subject: Re: [Radiance-general] Re: direct/indirect photometric
From: Greg Ward
To: [email protected]
Reply-To: [email protected]
Hi John,
You have a point, especially since the illum sphere will never be
subdivided during source sampling -- i.e., its distribution will always
eminate from a point. However, you must do one thing if you substitute
the geometry for a fixture; you must multiply the A1 scalefactor in the
brightdata primitive by the ratio of the illum sphere area divided by
the illum replacement geometry area, or the total lumens will not be
maintained during the switch. Alternatively, you can specify an illum
radius whose area (4*PI*radius^2) exactly equals the area of the
replacement geometry.
-Greg
> From: John An
>
> Wouldn't I need to modify the illum sphere when I'm creating a linear
> fluorescent luminaire so that the illum geometry fits tightly around
> the long luminaire? Is it ok to create a sphere with a radius of 2
> feet for a 4 feet long luminaire, and then just leave it alone?
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<DIV>Greg and John An,</DIV>
<DIV> </DIV>
<DIV>Unless the new version of Radiance is significantly different that when I wrote chapter 5, I do not think that you need to change A1 if you follow the method described in the book. The method was specifically designed to address linear sources. It is also the method employed in the luminaire editor in Desktop Radiance.</DIV>
<DIV> </DIV>
<DIV>Is it still true that the "lboxcorr" function automatically corrects for the surface area of the emitter? If not, then we have a major re-write on our hands for the new edition.</DIV>
<DIV> </DIV>
<DIV>-Chas<BR><BR><B><I>[email protected]</I></B> wrote:</DIV>
<BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid"><BR>Date: Mon, 26 May 2003 09:02:47 -0700<BR>Subject: Re: [Radiance-general] Re: direct/indirect photometric<BR>From: Greg Ward <[email protected]><BR>To: [email protected]<BR>Reply-To: [email protected]<BR><BR>Hi John,<BR><BR>You have a point, especially since the illum sphere will never be <BR>subdivided during source sampling -- i.e., its distribution will always <BR>eminate from a point. However, you must do one thing if you substitute <BR>the geometry for a fixture; you must multiply the A1 scalefactor in the <BR>brightdata primitive by the ratio of the illum sphere area divided by <BR>the illum replacement geometry area, or the total lumens will not be <BR>maintained during the switch. Alternatively, you can specify an illum <BR>radius whose area (4*PI*radius^2) exactly equals the area of the <BR>replacement geometry.<BR><BR>-Greg<BR><BR>> From: John An <[email protected]><BR>><BR>> Wouldn't I need to modify the illum sphere when I'm creating a linear <BR>> fluorescent luminaire so that the illum geometry fits tightly around <BR>> the long luminaire? Is it ok to create a sphere with a radius of 2 <BR>> feet for a 4 feet long luminaire, and then just leave it alone?<BR><BR><BR><BR>--__--__--<BR><BR>_______________________________________________<BR>Radiance-general mailing list<BR>[email protected]<BR>http://www.radiance-online.org/mailman/listinfo/radiance-general<BR><BR><BR>End of Radiance-general Digest</BLOCKQUOTE>
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