[Radiance-general] Re: Radiance simulations maintain 200 lux minimum

[Jack de Valpine]

Hi Caroline,

I can think of three possible things that you might want to look into:

   1. Illums - these are imposter geometry to help optimize daylight
      simulation in interior environments. I see that you have the
      illum= line in the rif file, however since you are getting the
      warning about "no lights found" it is likely that there is some
      problem: A) illum geometry is directionally dependant, the surface
      normal must point into the room. To create a polygon in Autocad
      with the normal pointing into the room, the polygon (a closed
      pline or 3dface for example) can be constructed by generating
      vertices in a counter clockwise manner, for example if the polygon
      is built in the xy plane then drawing it counter clockwise would
      result in a normal that point in positive z. B) I do not use the
      rad program so I am not so sure about this, but does the geometry
      that appears in the illum= line also need to apear in the scene= line?
   2. Ambient value - this allows a baseline ambient value to be
      established for the scene, this can be estimated or precalculated
      with a different script (although I am not sure how DR deals with
      this). If this value is too high then the images can have the kind
      of "glowy" appearance. I am guessing that a default value is being
      used from the information in the rif file. This may need to
      estimated by hand for best results.
   3. Indirect - this indicates how many ambient bounces to calculate.
      If you are after accurate results this number probably needs to be
      2 and perhaps more depending on other factors.

-Jack

Caroline Prochazka wrote:

>Hello all,
>
>As Greg suggested, I have posted my results to my
>website. No fancy links between them, and the text
>files are done as jpegs, but the info is there.
>
>I ran simulations of a 15m x 15m room. The west wall
>has 4 windows and the north, south and east walls each
>have 1 central window. I simulated December 21st in
>Toronto for noon, 4pm and 6pm. According to other
>software and my weather data, there is no sunlight at
>6pm on Dec21, and the sun is quite low, but not yet
>set at 4pm. I did not model any exterior obstructions.
>
>Using the Desktop Radiance interface in AutoCAD I
>generated .rif files for the time/day selections
>(Radiance>Simulation>Camera...). Then in Command
>Prompt I performed RAD on the various .rif files.
>
>The sky definitions all appear identical, except for
>the time markers in the top line.
>The .riff and sky.rad files are posted here:
>http://www.geocities.com/cjprocha/Sky_and_Rif_files.jpg
>
>The RAD command ran through my camera views
>successfully, but generated some warnings:
>warning - no light source found. Well of course, I
>have no luminaires (as suggested in the Desktop
>Radiance FAQ), I am studying daylighting, so I presume
>I can move on despite this message.
>and
>warning - aiming failure for light source
>"softwaretest4_38.4.2". Looking at the DesktopRadiance
>FAQ, online, there would not seem to be any reason for
>this warning, based on the model I have drawn. No
>concave items, no cylinders, no rings with holes, etc.
>
>The entire script for my RAD run of Dec 21 at noon is
>posted here:
>http://www.geocities.com/cjprocha/Rad_Script.jpg
>apologies for the fuzziness.
>
>So the resulting images are posted as follows:
>December 21, noon:
>http://www.geocities.com/cjprocha/Dec21_12_ca6_images.jpg
>December 21, 4pm:
>http://www.geocities.com/cjprocha/Dec21_16_ca6_images.jpg
>December 21, 6pm:
>http://www.geocities.com/cjprocha/Dec21_18_ca6_images.jpg
>The false color maps are generated within the winimage
>screen (Analysis>False color>choose metric,
>illuminance, max=1000, intervals=10)
>
>Note the centre of the floor of the room (roughly the
>centre of the floor area as I have cast my camera
>view) is near 200 lux in all three cases, even when
>there are no luminaires and the scene is after
>sun-set.
>
>I've also noticed that the 6pm version produces an
>ambient glow in the room, both in general and more
>specifically along the ceiling edge. Where is this
>light coming from? 
>
>Things I HAVE checked. 
>1.All planes are in contact along all edges. 
>2.All windows have their surface normals pointing 
>inwards. 
>3.Double and triple checked (multiple runs with same
>results) each of these simulations.
>
>I am a new user so my use of the Command Prompt to do
>most of this is limited. Any suggestions would be
>greatly appreciated, though.
>
>
>Caroline
>
>
>	
>		
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>  
>

-- 
#	John E. de Valpine
#	president
#
#	visarc incorporated
#	http://www.visarc.com
#
#	channeling technology for superior design and construction

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