Sky illumination vs. mkillum

radiance-general
1

Hi all,

I'm tearing my hair out here trying to grok mkillum windows vs. sky illumination through the window.

I am trying to visualise the DIRECT sky factor on the floor of a room before and after a new building is put in. The green area is the area that is above 0.2% sky factor before the building and the red area is the area that is above 0.2% sky factor after the new building is put in.

I have tried with and without mkillum:

Skyglow:

Mkillum:

Note that the skyglow one would seem to be much more accurate (basically a big building that covers almost all the window in the top left edge is put in), but the mkillum one has smoother edges.

I guess what I just do not understand after hours of playing with all the rendering and mkillum settings is how to either:

* get rid of the speckling in the skyglow render

or

* make the mkillum render actually accurate (in particular, the green leakage in the top left corner seems wrong)

Can anyone give any suggestions?

Thanks,

Chris

2

Chris,

I am trying to visualise the DIRECT sky factor on the floor of a room
before and after a new building is put in. The green area is the area
that is above 0.2% sky factor before the building and the red area is
the area that is above 0.2% sky factor after the new building is put in.

This looks like a Rights to Light study, yes? In any case, for the direct sky
factor, whack up ad to whatever gives you a converged value - try a few
in steps of two starting -ad 1024. Turn interpolation off (-aa 0) and, of course,
use -ab 1. If it's RTL, then a uniform sky is used rather than the CIE ovc and
I seem to recall that the window is an aperture without any glazing.

I really wouldn't bother with a source window for something like this.

If the grid was orthogonal, I'd be tempted to supply a grid of points to
rtrace and process the results in my preferred crunching/display software.

-John

···

-----------------------------------------------
Dr. John Mardaljevic
Senior Research Fellow
Institute of Energy and Sustainable Development
De Montfort University
The Gateway
Leicester
LE1 9BH, UK
+44 (0) 116 257 7972
+44 (0) 116 257 7981 (fax)

[email protected]
http://www.iesd.dmu.ac.uk/~jm