<div>Thank you for clarification. Is there any material for novice besides reference listed in this website: <a href="http://radsite.lbl.gov/radiance/">http://radsite.lbl.gov/radiance/</a>? </div>
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<div>Jia <br><br></div>
<div class="gmail_quote">On Sun, Jan 17, 2010 at 5:58 AM, Thomas Bleicher <span dir="ltr"><<a href="mailto:tbleicher@googlemail.com">tbleicher@googlemail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">Jia.<br><br>See further answers within ...<br>
<div class="im"><br>On Sat, Jan 16, 2010 at 4:37 PM, Hu,Jia <<a href="mailto:hujia06@gmail.com">hujia06@gmail.com</a>> wrote:<br>> Hello Andy:<br>><br>> Sorry for my late reply. I am new for Radiance and have to learn more to<br>
> reply you. Before discussing the previous question, could I ask how I<br>> can open the text editor and save as file with extension like .rad after I<br>> install Ubuntu 9.10 because I am unfamiliar with Ubuntu (Linux)?<br>
<br></div>I currently don't have an Ubuntu system installed but I think this still<br>applies:<br><br>> Gedit is the default Ubuntu text editor, which you can launch by clicking<br>> Applications->Accessories->Text Editor on the desktop menu system.<br>
<br>When you save files always make sure that you save in plain<br>text (*.txt).<br>
<div class="im"><br>> For the question in my last email, I asked that because someone<br>> did some simulations before but the results seems weird. In those<br>> simulations, two identical small offices are developed with only one<br>
> difference. In one office, the angles of the blinds are 0 degree. For<br>> another, the windows are separated into three sections (the height<br>> for each section is the same). The blinds with 0 degree are also the<br>
> same for each section. The illuminance of the sensor points are<br>> calculated for the two offices. Theoretically, the illuminance should<br>> be identical or quite similar. But as I said in my last email, the<br>
> illuminance shows a big difference.<br><br></div>As Andy said, without details about the rendering parameters and<br>the scene/window geometry it's hard to tell why the values are so<br>different. Scenes with blinds are sensitive to the right rendering<br>
parameters because you have to account for multiple reflections<br>to achieve satisfactory results. If the scenes were rendered with<br>settings that are not accurate enough you will get largely differing<br>results.<br><br>
Another option is that the two scenes had different sky settings<br>which will also result in different (absolute) illuminance values.<br>
<div class="im"><br>> In addition to your explanation, is that right another possible reason is<br>> the computer hardware difference. For example, one computer may calculate<br>> 5+3=8, while another calculates 5+3=7.8888. If possible, Is there any test<br>
> file to test the accuracy of computer before running Radiance?<br><br></div>Radiance was written to be usable on multiple platforms. There<br>is a built in tolerance for rounding errors which takes care of the<br>above situations. However, you can get different results (to the<br>
point where the calculations are untrustworthy) if you apply very<br>strong optimisation options when compiling the binaries. I assume<br>that you have used the binaries from the Debian/Ubuntu distribution<br>provided by Bernd Zeimetz so this should not be the cause of<br>
your problem.<br><br>There is no standard test scenario for Radiance. I think you can<br>install example scenes in Ubuntu as a separate package. Some<br>of these are also discussed the book "Rendering with Radiance".<br>
<br>Once you have Radiance running (i.e. it produces images that look<br>about right) it's hard to verify the accuracy because each rendering<br>depends on the scene complexity and selected rendering parameters.<br>Basically you have to do a set of verification renderings with changing<br>
settings until you have shown that your error is within a certain limit.<br><br>I also used other lighting simulation apps to check that my<br>results are at least in the same order of magnitude (especially<br>when artificial lighting is involved).<br>
<br>Mark Stock has written a benchmark scene which you can use<br>to test your installation. It will run for a few hours, though. It renders<br>a scene at high quality settings (for a picture output) and if your<br>result looks like the (tiny) image on his page Radiance works fine.<br>
<br><a href="http://markjstock.org/pages/rad_bench.html" target="_blank">http://markjstock.org/pages/rad_bench.html</a><br><br>Regards,<br><font color="#888888">Thomas<br></font>
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