[Radiance-general] Re: ambient setting for very large scenes

[Jack de Valpine]

Hi Jelle,

Well here is a question. I am not sure how large the interior spaces are 
that you are trying to show but wouldn't using illums (mkillum) at the 
openings enable one to get a reasonable (for the purposes of this study) 
approximation of ambient light while using a lower set of overall 
ambient terms?

-Jack

Jelle Feringa / EZCT Architecture & Design Research wrote:
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>  
>
> Hi!
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>  
>
> Thanks so much for the overwhelming replies!
>
>  
>
> Absurd it is. This is a problem when you have a scene like yours. You
>
> want some distant object or scenery to be visible out the window, for
>
> example, so you put it in your model and then the images seem really
>
> flat or have light leaks because the -ar isn't high enough. One thing
>
> you could do is cheat, and place the objects closer to your area of
>
> interest than they really are, scaling them up a bit. This works for
>
> treelines and things like that, anyway. Another would be to exclude the
>
> distant objects from the ambient calculation with the -ae option, the
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> problem there (and maybe some folks here have input on this) is that
>
> your objects are outside, your area of interest is inside, so your -av
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> is likely to be too low for the exterior objects (which is how all the
>
> indirectly lit surfaces derive their radiance information when their
>
> materials are on the -ae list).
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>  
>
> -ar 5000 would take forever to render!
>
>  
>
> Actually, it wasn't *that* bad! An hour and a half (fairly lo-res, but 
> good enough for its purpose) wasn't that dramatic, so I suppose that 
> the algorithm for getting a reasonable --ar setting really is quite 
> ok! Still I'm sure that there are more intelligent strategies rather 
> than brute-force computing power...
>
> I'm interested to get fairly optimal ambient settings since I'm 
> producing a sun path study, so I need to render quite a quantity of 
> imagery here...
>
> //if fellow pythoniasts on the list are interested in my script, let 
> me know, it would be interesting the have a
>
> //a solid python script for sun-path that runs beautifully 
> cross-platform & on multi-core machines...
>
>  
>
> Good luck, Jelle.
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>  
>
> Thanks Rob!
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>  
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> Hi Rob and Jelle,
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>  
>
> Although I have not tried this, what about rendering a light probe of
>
> the exterior environment (using parameters suitable for an exterior
>
> scene) and then using the light probe to supply the background for the
>
> interior scene?
>
>  
>
> -Jack
>
>  
>
> Hey Jack!
>
>  
>
> That's an interesting suggestion!
>
> Although since I'm producing a sun path study, HDR isn't really the 
> way to go, it be fairly work-intensive ;')
>
> Interesting idea though, did you apply this technique perhaps in some 
> of the work shown on your site?
>
>  
>
>  
>
> Well there you go. However, we do not what exactly Jelle's objectives
>
> are with respect to numeric accuracy.
>
>  
>
> It's in-between; my goal is to give architects accurate feedback about 
> the lighting conditions on the project they're working on. Their 
> interest is a more visual interest than numerical. Missing a couple of 
> lux isn't too problematic, the idea is to be able to communicate the 
> lighting conditions in the building in a visual & fairly accurate manner.
>
>  
>
>  
>
>  
>
> Hi Lars!
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>  
>
> I just have to quote Greg, as he replied on a similar question I had
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> posted some days ago in great detail:
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>  
>
>  > One other note -- you might try setting -ar 0 in your case.
>
>  > If you have really large and small geometry that require
>
>  > enormous -ar settings, you may be better off without it.
>
>  
>
> I have a scene which would also require an incredible high ar here, and
>
> got processes close to 2GB (which will always lead to slow rendering on
>
> today's machines).
>
>  
>
> That's a very interesting suggestion!
>
> Will try that right away!
>
> Cheers,
>
>  
>
> -jelle
>
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>
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-- 
# Jack de Valpine
# president
#
# visarc incorporated
# http://www.visarc.com
#
# channeling technology for superior design and construction

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