[Radiance-general] Gensky and ground brightness
Fitzsimmons, Rob
[email protected]
Tue, 30 Dec 2003 17:08:09 -0600
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Happy holidays to all
another question...
When using gensky, how do I get a realistic level to create a ground glow?
Looking at skybright.cal, I notice A3 might be the value I'm looking for
skybright.cal
{ RCSid: $Id$ }
{
Sky brightness function for sunny and cloudy skies.
Additional arguments required for calculation of skybright:
A1 - 1 for CIE clear, 2 for CIE overcast,
3 for uniform, 4 for CIE intermediate
A2 - zenith brightness
A3 - ground plane brightness
A4 - normalization factor based on sun
direction
A5,A6,A7 - sun direction
}
In the following example, would I use 20.1 (the suggested ambient value) or
2.94e+01 (the 3rd attribute)
Or niether? Am I way off? I'm sure it depends on whether your on a black
sand beach or a ski slope, but is there a general value?
Thanks
Rob F
# gensky 6 21 12:00PST +s -a 44.47 -o 123.26
# Local solar time: 11.76
# Solar altitude and azimuth: 68.8 -9.2
# Ground ambient level: 20.1
void light solar
0
0
3 7.13e+06 7.13e+06 7.13e+06
solar source sun
0
0
4 0.057775 -0.357455 0.932142 0.5
void brightfunc skyfunc
2 skybr skybright.cal
0
7 1 2.69e+01 2.94e+01 1.26e+00 0.057775 -0.357455 0.932142
skyfunc glow skyglow
0
0
4 .5 .5 .7 0
skyglow source sky
0
0
4 0 0 1 180
skyfunc glow groundglow
0
0
4 .4 .6 .38 0
groundglow source ground
0
0
4 0 0 -1 180
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<P><FONT SIZE=3D2>Happy holidays to all</FONT>
<BR><FONT SIZE=3D2>another question...</FONT>
<BR><FONT SIZE=3D2>When using gensky, how do I get a realistic level to =
create a ground glow?</FONT>
<BR><FONT SIZE=3D2>Looking at skybright.cal, I notice A3 might be the =
value I'm looking for</FONT>
</P>
<P><FONT SIZE=3D2>skybright.cal</FONT>
<BR><FONT SIZE=3D2>{ RCSid: $Id$ }</FONT>
<BR><FONT SIZE=3D2>{</FONT>
<BR><FONT SIZE=3D2> Sky brightness function for =
sunny and cloudy skies.</FONT>
</P>
<P><FONT SIZE=3D2> Additional arguments =
required for calculation of skybright:</FONT>
</P>
<P><FONT SIZE=3D2> =
A1 &nbs=
p; - 1 for CIE =
clear, 2 for CIE overcast,</FONT>
<BR><FONT =
SIZE=3D2> &nb=
sp; &nb=
sp; 3 for =
uniform, 4 for CIE intermediate</FONT>
<BR><FONT SIZE=3D2> =
A2 &nbs=
p; - zenith =
brightness</FONT>
<BR><FONT SIZE=3D2> =
A3 &nbs=
p; - ground plane =
brightness</FONT>
<BR><FONT SIZE=3D2> =
A4 &nbs=
p; - =
normalization factor based on sun direction</FONT>
<BR><FONT SIZE=3D2> =
A5,A6,A7 &nbs=
p; - sun direction</FONT>
<BR><FONT SIZE=3D2>}</FONT>
</P>
<P><FONT SIZE=3D2>In the following example, would I use 20.1 (the =
suggested ambient value) or 2.94e+01 (the 3rd attribute)</FONT>
<BR><FONT SIZE=3D2>Or niether? Am I way off? I'm sure it depends =
on whether your on a black sand beach or a ski slope, but is there a =
general value?</FONT></P>
<P><FONT SIZE=3D2>Thanks </FONT>
<BR><FONT SIZE=3D2>Rob F</FONT>
</P>
<P><FONT SIZE=3D2># gensky 6 21 12:00PST +s -a 44.47 -o 123.26</FONT>
<BR><FONT SIZE=3D2># Local solar time: 11.76</FONT>
<BR><FONT SIZE=3D2># Solar altitude and azimuth: 68.8 -9.2</FONT>
<BR><FONT SIZE=3D2># Ground ambient level: 20.1</FONT>
</P>
<P><FONT SIZE=3D2>void light solar</FONT>
<BR><FONT SIZE=3D2>0</FONT>
<BR><FONT SIZE=3D2>0</FONT>
<BR><FONT SIZE=3D2>3 7.13e+06 7.13e+06 7.13e+06</FONT>
</P>
<P><FONT SIZE=3D2>solar source sun</FONT>
<BR><FONT SIZE=3D2>0</FONT>
<BR><FONT SIZE=3D2>0</FONT>
<BR><FONT SIZE=3D2>4 0.057775 -0.357455 0.932142 0.5</FONT>
</P>
<P><FONT SIZE=3D2>void brightfunc skyfunc</FONT>
<BR><FONT SIZE=3D2>2 skybr skybright.cal</FONT>
<BR><FONT SIZE=3D2>0</FONT>
<BR><FONT SIZE=3D2>7 1 2.69e+01 2.94e+01 1.26e+00 0.057775 -0.357455 =
0.932142</FONT>
</P>
<P><FONT SIZE=3D2>skyfunc glow skyglow</FONT>
<BR><FONT SIZE=3D2>0</FONT>
<BR><FONT SIZE=3D2>0</FONT>
<BR><FONT SIZE=3D2>4 .5 .5 .7 0</FONT>
</P>
<P><FONT SIZE=3D2>skyglow source sky</FONT>
<BR><FONT SIZE=3D2>0</FONT>
<BR><FONT SIZE=3D2>0</FONT>
<BR><FONT SIZE=3D2>4 0 0 1 180</FONT>
</P>
<P><FONT SIZE=3D2>skyfunc glow groundglow</FONT>
<BR><FONT SIZE=3D2>0</FONT>
<BR><FONT SIZE=3D2>0</FONT>
<BR><FONT SIZE=3D2>4 .4 .6 .38 0</FONT>
</P>
<BR>
<P><FONT SIZE=3D2>groundglow source ground</FONT>
<BR><FONT SIZE=3D2>0</FONT>
<BR><FONT SIZE=3D2>0</FONT>
<BR><FONT SIZE=3D2>4 0 0 -1 180</FONT>
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