[Radiance-general] Blotching caused by translucent material

[Örn Erlendsson]

Thank you all for your reply. I have now tried several variations with your suggestions and although the blotching issue is not resolved, the images do get slightly better. Could the issue in fact be that the diffuse and specular transmissive properties are so low that in reality very little light would pass into the scene, thus causing a very low light condition closely represented by the blotching case we see from the simulations? 

Just to clarify the light transmission of translucent glazing is equal to the sum of the diffuse and specular transmission.... right?

Örn

From: amcneil at lbl.gov
Date: Fri, 12 Jun 2015 12:17:55 -0700
To: radiance-general at radiance-online.org
Subject: Re: [Radiance-general] Blotching caused by translucent material

Chris, I think you're suggestion is valid, particularly for reducing the size of the blotches.Andy


On Fri, Jun 12, 2015 at 11:03 AM, Christopher Rush <Christopher.Rush at arup.com> wrote:








I retract my answer. Andy is right about it being splotches in the direct transmission. I was too quick to jump to conclusions when I read your subject and barely looked at the images.
 


From: Christopher Rush [mailto:Christopher.Rush at arup.com]


Sent: Friday, June 12, 2015 1:52 PM

To: Radiance general discussion

Subject: Re: [Radiance-general] Blotching caused by translucent material


 
Orn,
With clear glass, a very significant contribution is made by the direct sun, so all the ambient bounces (and their calculation parameters) contribute less to the scene, and you see less blotches.
 
For the translucent glass, try again with all of your first run parameters, but instead of -ar 64 try -ar 500 or -ar 1000. This probably has the biggest impact on visibility of blotches. This is particularly
 important if your model includes a room that’s part of a much larger building, or a full building floor with a very large site context modeled around it.
 
In the parameters you tested in the second run, when you increased –ad and lowered –aa those should also improve accuracy, but might not be necessary depending on how much importance you put on accuracy versus
 calculation time.

 

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