[Radiance-general] Ambient file Q's
Jack de Valpine
[email protected]
Tue, 06 Jan 2004 15:43:49 -0500
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Hi Rob,
I remember having the same thought when I was learning radiance (which I
am still learning by the way). Unfortunately, you cannot reuse an
ambient file in this manner where you progressively refine the
parameters and thus refine the ambient data. Generally, if you change
the ambient parameters then you need to start off with a fresh ambient
file. The one note here is that it is possible to "relax" certain of the
parameters after first doing an overture calculation to fill the ambient
cache. The -aa, -ad and -as parameters can be reduced after the overture
calculation. For example, just looking at the ambient parameters:
pass 0 (overture)
-ab 2 -ar 200 -ad 4096 -as 2048 -aa .15
pass 1
-ab 2 -ar 200 -ad 2048 -as 1024 -aa .25
Note that the overture calculation is performed by running rpict on a
small image size (64x64 for example) and discarding the image output.
The point is to populate the ambient file with data. Rendering with
Radiance has further information on this in John Mardaljevic's chapter
(6) on Daylighting Simulation.
-Jack de Valpine
Fitzsimmons, Rob wrote:
> I rendered a series of images with -ad 2048 -as 1024 -ar 52 -af
> file.amb (taking many hours to render)
> They came out splotchy, so I increased -ad 4096 -as 2048 -ar 200 -af
> file.amb (building upon the same data)
> I expected it to take quite a while to render, but they took ~ 5 to
> 10 minutes and I saw no real improvement
> my question is the nature of the ambient file..
> If I start it with a lower quality, can I improve it? Or is it similar
> to trying to "upres" a Photoshop from 300 dpi to 600dpi
>
> judging by my results, this seems to be the case
>
> Thanks
>
> Rob F
>
--
# John E. de Valpine
# president
#
# visarc incorporated
# http://www.visarc.com
#
# channeling technology for superior design and construction
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Hi Rob,<br>
<br>
I remember having the same thought when I was learning radiance (which I
am still learning by the way). Unfortunately, you cannot reuse an ambient
file in this manner where you progressively refine the parameters and thus
refine the ambient data. Generally, if you change the ambient parameters
then you need to start off with a fresh ambient file. The one note here is
that it is possible to "relax" certain of the parameters after first doing
an overture calculation to fill the ambient cache. The -aa, -ad and -as parameters
can be reduced after the overture calculation. For example, just looking
at the ambient parameters:<br>
<br>
pass 0 (overture)<br>
-ab 2 -ar 200 -ad 4096 -as 2048 -aa .15<br>
<br>
pass 1<br>
-ab 2 -ar 200 -ad 2048 -as 1024 -aa .25<br>
<br>
Note that the overture calculation is performed by running rpict on a small
image size (64x64 for example) and discarding the image output. The point
is to populate the ambient file with data. Rendering with Radiance has further
information on this in John Mardaljevic's chapter (6) on Daylighting Simulation.<br>
<br>
-Jack de Valpine<br>
<br>
<br>
Fitzsimmons, Rob wrote:<br>
<blockquote type="cite"
cite="mid7B2F6EA5E35E214882CB9828962BC3CF04D69297@corvallis.summit.fiserv.com">
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<p><font size="2">I rendered a series of images with -ad 2048 -as 1024
-ar 52 -af file.amb (taking many hours to render)</font> <br>
<font size="2">They came out splotchy, so I increased -ad 4096 -as 2048
-ar 200 -af file.amb (building upon the same data)</font> <br>
<font size="2"> I expected it to take quite a while to render, but they
took ~ 5 to 10 minutes and I saw no real improvement</font> <br>
<font size="2">my question is the nature of the ambient file..</font> <br>
<font size="2">If I start it with a lower quality, can I improve it? Or
is it similar to trying to "upres" a Photoshop from 300 dpi to 600dpi</font></p>
<p><font size="2">judging by my results, this seems to be the case</font>
</p>
<p><font size="2">Thanks</font> </p>
<p><font size="2">Rob F</font> </p>
</blockquote>
<br>
<pre class="moz-signature" cols="$mailwrapcol">--
# John E. de Valpine
# president
#
# visarc incorporated
# <a class="moz-txt-link-freetext" href="http://www.visarc.com">http://www.visarc.com</a>
#
# channeling technology for superior design and construction</pre>
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