[Radiance-general] gensky -u not uniform?

[John Mardaljevic]

Hi Jan,

Ah, a trip down memory lane -- I think I first came across this in 2002.  Gensky applies a mixing function around the horizon to `blend' the brightness of the sky and whatever might be below, e.g. usually the glowing ground but it's still applied if there's nothing below the horizon.  I guess this was for purely visual appearance. A small change to skybright.cal should get rid of the blending at the horizon:

Change:

skybr = wmean((Dz+1.01)^10,
		select(A1, sunnysky, cloudysky, unifsky, intersky),
		(Dz+1.01)^-10, A3);

to:

skybr = if( Dz, select(A1, sunnysky, cloudysky, unifsky, intersky), A3);

That should fix it.

I didn't want to alter how skybright.cal is used, so I created another file (imaginatively) called skybright_nomix.cal.  At the time, I'm sure Greg must have nudged me in the right direction.

Cheers
John

John Mardaljevic PhD FSLL FIBPSA
Professor of Building Daylight Modelling
School of Architecture, Building & Civil Engineering
Loughborough University
Loughborough
Leicestershire
LE11 3TU, UK

Tel: +44 1509 222630 (Direct)
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j.mardaljevic at lboro.ac.uk

http://www.lboro.ac.uk/departments/abce/staff/john-mardaljevic

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