Radiance-general Digest, Vol 31, Issue 23


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

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

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).

-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.

Thanks Rob!

Hi Rob and Jelle,

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?


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!

I just have to quote Greg, as he replied on a similar question I had

posted some days ago in great detail:

> 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!