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
and alight areas. For the distance of 35 meters a shading element has be
at least 40cm wide to produce a distinguishable

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

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" <[email protected]>
Date: March 11, 2008 8:31:30 AM PDT
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

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

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" <[email protected]>
Date: March 11, 2008 8:31:30 AM PDT
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