[Radiance-general] Confused by GenSky

[Paul Lovell]

Hi Everyone,

It's been some time since I asked a dumb question of the clever people at radiance-general, so here goes...

I'm trying to render some scenes with varying illumination, in particular I want to vary the diffuseness of the illumination.

Currently I'm doing this with a hemi-field of spherical lights, with a non-homogenous density. This works fine for example <http://www.youtube.com/watch?v=zhsMeTtIPFA&list=HL1379509671&feature=mh_lolz>

However, that's for my made-up illumination, I need to confirm that what I'm doing bears any relationship to "real" illumination, i.e. using gensky with "+s", "-s" etc.

I've tried rendering the same scene while specifying the sun position using gensky, for example this works fine:

% Gensky settings: -ang 45 45 +s
%
% # C:\Program Files (x86)\MinGW-Radiance\bin\gensky -ang 45 45 +s
% # Ground ambient level: 14.8
%
% void light solar
% 0
% 0
% 3 6.77e+006 6.77e+006 6.77e+006
%
% solar source sun
% 0
% 0
% 4 -0.500000 -0.500000 0.707107 0.5
%
% void brightfunc skyfunc
% 2 skybr skybright.cal
% 0
% 7 1 9.56e+000 2.12e+001 5.71e-001 -0.500000 -0.500000 0.707107
%

However, when I try with the -s sky:

% Gensky settings: -ang 45 45 -s
%
% # C:\Program Files (x86)\MinGW-Radiance\bin\gensky -ang 45 45 -s
% # Ground ambient level: 14.8
%
% void brightfunc skyfunc
% 2 skybr skybright.cal
% 0
% 7 1 9.56e+000 2.12e+001 5.71e-001 -0.500000 -0.500000 0.707107

It just fails to render "pfilt: picture too dark or too bright ". The -c -u -i skies also don't render.

I'm running minGW radiance in windows (with a Matlab wrapper), the +s, -s, -c and -u skies work fine when I specify time and geographical location with gensky, but I want to specify the exact sun position.

Anyone have any suggestions?

best wishes,

George



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