[Radiance-general] soft edged shadows

[Mark Stock]

Kai,

And if you are really hard-core, you can approximate the single 
sun's disk with a number of smaller disks, filling the original. 
This helps smooth out penumbras cast by long shadows, I've found.

Of course, try the "-dj 0.7" first. That might be enough. You 
will, of course, need to render at several times your final, 
desired resolution, and reduce afterwards.

Mark

On Tue, 11 Mar 2008, Greg Ward wrote:

> Hi Kai,
>
> Try rendering with -dj 0.7 or so.  If you are using rad, this can be done by 
> setting PENUMBRA=True.
>
> Best,
> -Greg
>
>> From: "Kai Babetzki" <babetzki at transsolar.com>
>> Date: March 11, 2008 8:31:30 AM PDT
>> Dear Radiance Community,
>> I'm more a faithful reader (than writer) of this newsgroup due to more 
>> common problems I had to deal with in the past.
>> But in my current project the architect wants a horizontally fully glazed 
>> roof for his atria. The roof height
>> is 35m and due to sun protection reasons the roof should be fritted.
>> 
>> The main design criteria is, that the fritting should be realized in a way, 
>> that you can distinguish between shaded
>> and alight areas on the floor.
>> 
>> We did some very rough experiments and saw very weak edges between shaded
>> and alight areas. For the distance of 35 meters a shading element has be at 
>> least 40cm wide to produce a distinguishable
>> 
>> shadow on the floor.
>> 
>> If I model this with Radiance the results show always very strong shadows 
>> with very sharp edges and I can't see any expected diffraction effects.
>> 
>> Sorry for the long introduction but my question is very short: Is it 
>> possible to model this effect with Radiance?
>> 
>> Best regards,
>> Kai
>
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