[Radiance-general] Blotching caused by translucent material

[Örn Erlendsson]

Hi,

Can someone help me to set the Radiance parameters to eliminate blotching in my images? I am running renderings, DGP and glare simulations for a simple geometry. I have had no issues with the images when I use clear glazing. One of the tests that I am conducting, however, uses translucent glazing with the following parameters:

void trans testTrans007 0.478 0.478 0.478 0.000 0.010 0.178 0.635
I've run radiance with two different parameter sets, the first with
_av_ is set to 0xScale is set to 2_ab_ is set to 6_dc_ is set to 0.5_aa_ is set to 0.2_ad_ is set to 2048_st_ is set to 0.5yScale is set to 2_ps_ is set to 4_ar_ is set to 64_as_ is set to 2048_ds_ is set to 0.25_pt_ is set to 0.1_dr_ is set to 1_pj_ is set to 0.9_dp_ is set to 256_dt_ is set to 0.25_lr_ is set to 6_dj_ is set to 0.5_lw_ is set to 0.01
resulting in the image named Blotching001
The second case has the following parameters:
_av_ is set to 0xScale is set to 6_ab_ is set to 6_dc_ is set to 0.75_aa_ is set to 0.1_ad_ is set to 4096_st_ is set to 0.15yScale is set to 6_ps_ is set to 2_ar_ is set to 128_as_ is set to 4096_ds_ is set to 0.05_pt_ is set to 0.05_dr_ is set to 3_pj_ is set to 0.9_dp_ is set to 512_dt_ is set to 0.15_lr_ is set to 8_dj_ is set to 0.7_lw_ is set to 0.005
resulting in the image named Blotching002. I have also attached an image with no blotching. This case uses glazing with 65% light transmittance. 
Although the second case is much better, it is still very bad for hours when the sun is lower in the sky. The two above images are rendered for a clear sky at 18:00 in Germany.

Can someone help?

Kind regards,
Orn Erlendsson
 		 	   		  
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