[Radiance-general] RE : Light Shelf Reflections

[Chris Coulter]

Shamim.

You can export the analysis from Ecotect (it becomes a list of xyz coordinates with normal direction vector of that sensor). You can then use rtrace to calculate your illuminance values. You will need to create two grid files, one with normal vectors pointing up (0 0 1) for light arriving from the ceiling and a grid with normals pointing down (0 0 -1) for light bouncing off the floor.

Using the "Final Render" option in the Radiance Analysis/Export panel of Ecotect allows you to assign a grid ("Generate Point Data" check box). If you are using radiance from the command line rather than the Ecotect interface, the best way I've found to save a grid file is to set the output to "Daysim header" and uncheck "Auto-run Daysim". The analysis grid will be in the specified folder, saved as a .pts file.

I suggest looking through this tutorial for step by step guidance. http://www.gsd.harvard.edu/research/gsdsquare/Publications/GettingStartedwithEcotectRadianceDaysim.pdf

Best of luck.

Chris Coulter
Senior Lighting Designer
Buro Happold Consulting Engineers
100 Broadway, 23rd Floor
New York, NY 10005

From: Shamim Javed [mailto:javeds2006 at gmail.com]
Sent: Monday, March 18, 2013 8:48 AM
To: Radiance general discussion
Subject: Re: [Radiance-general] RE : Light Shelf Reflections

I do not know if radiance supports 'analysis grid' or its equivalent but if it did, can I suspend one in 'mid-air' (say one at 30" off the floor) and expect to get illuminance values off it?  Can it be a two-sided grid registering both the light coming off the ceiling and the floor?  The referenced file may explain my question a bit more:
https://www.dropbox.com/s/f5zsvjitub6fs6x/Analysis%20Grid_Question.pdf

Shamim.

On Sun, Mar 17, 2013 at 11:20 AM, Rob Guglielmetti <rob.guglielmetti at gmail.com<mailto:rob.guglielmetti at gmail.com>> wrote:
The most direct way to derive the surface normal direction of a polygon is to simply look at the draw order of the polygon's vertices. Radiance polygons follow the "right hand rule", which means that a polygon that is planar to the x,y and drawn in a counter-clockwise fashion will have the surface normal running along the positive z axis.

Sent from my iPad

On Mar 16, 2013, at 11:43 PM, Shamim Javed <javeds2006 at gmail.com<mailto:javeds2006 at gmail.com>> wrote:
Andy,

How could you tell by just looking at the numbers that my ceiling surface normal was facing up?

I am trying to import the results of the radiance simulation (with bands of light hitting the floor) on to an analysis grid to finally generate an illumination graph that would have progressive 'bumps' reflecting these light bands.  https://www.dropbox.com/s/owvm7gqtamicdou/analysis%20grid.pdf
Any suggestions on an effective way of doing this would be much appreciated.

My radiance image has a distinct raddish tint unlike yours which came out with much more natural colors.  Any thoughts how I may improve this?

Shamim.

On Fri, Mar 15, 2013 at 7:18 PM, Andrew McNeil <amcneil at lbl.gov<mailto:amcneil at lbl.gov>> wrote:
one more thing  - can you double check that the ceiling surface normal is still facing downward (and that you didn't re-export geometry from ecotect).  It seems odd that there is one reflection of the the floor but none off the ceiling (the light that gets to the floor comes straight through the window and misses the light shelf).  There should be the same number of reflections from both.

Andy


On Fri, Mar 15, 2013 at 4:00 PM, Andrew McNeil <amcneil at lbl.gov<mailto:amcneil at lbl.gov>> wrote:
Shaim,
Can you try typing the commands I sent directly at the dos prompt?
That would tell us if it is a problem with the outdated version of Radiance you are using or if it is a problem with the Ecotect Radiance Control Panel.  I still think it is a problem with the latter as the commands settings didn't get into the header created by Radiance.

I'd rather determine if Ecotect related software is the cause now, rather than going further assuming that it is Radiance (which I doubt, but I am biased).

Andy

On Fri, Mar 15, 2013 at 3:45 PM, Randolph M. Fritz (i) <randolph+LD at panix.com<mailto:randolph+LD at panix.com>> wrote:
1998 is pretty old--it's possible we're giving you advice for newer versions.

NREL has a newer release of Radiance for Windows. I'm pretty sure you can hook it up with Ecotect, but I'm not sure exactly how.  Anyone done this?

Randolph



On 2013-03-15 20:19:41 +0000, Shamim Javed said:
I looked at the files generated by Radiance via Ecotect and it looks like the version of Radiance it is using is 3.1.8.  Here is a copy of one of the files generated:

"#?RADIANCE
oconv mirror_scorrected_sky.rad mirror_scorrected.rad
rpict -t 120 -vth -vp 9.628 4.564 6.510 -vd -1.701 0.360 -0.007 -vu 0 0 1 -vh 180 -vv 180 -vs 0 -vl 0 -dp 1024 -ar 45 -ms 0.17 -ds .3 -dt .1 -dc .5 -dr 1 -sj .7 -st .1 -ab 4 -af RCP.amb -aa .2 -ad 400 -as 64 -av 0.01 0.01 0.01 -lr 6 -lw .002 -i -x 64 -y 64 -ps 1
SOFTWARE= RADIANCE 3.1.8 lastmod Thu Sep 17 20:49:56 PDT 1998 by droberts on escher"

On Fri, Mar 15, 2013 at 2:22 PM, Randolph M. Fritz (i) <randolph+LD at panix.com<mailto:randolph%2BLD at panix.com>> wrote:
On 2013-03-15 15:17:59 +0000, Shamim Javed said:

I tried to replicate your simulation image (using Radiance via Ecotect) but without success so far.

Where did you get your copy of Radiance? Do you know what version it is?

If not, "getinfo foo.hdr" will identify the version of Radiance that generated foo.hdr.

Randolph




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