That old HDRI again...

[CapnPanic]

1) yes

2) using hdri for interior scenes, where all of the surrounding elements are cg seems kinda counter productive to me. i mean you _could_ use hdri and have it come in through the windows, but you could also use spot or area lights and have THOSE come in through the window, most likely with similar results. the look of the interior scne ewill mostly be dependant on if you let that light bounce around in your room (ie GI) or if you've got alot of fill lights etc

[rebeldreams]

Thanks for the reply!

To elaborate on the counter-intuitive nature of my initial post; The interior scene I am working on is a sort of "corner penthouse" apartment type look, with lots of big windows and a skylight - I figured HDRI was the quickest and most effective way of bouncing fill into the scene without having to rely on many area lights or directionals - plus I get more realistic shadows.

Well, I'll post the WIP in the appropriate section once I have something worth showing, and hopefully you'll see what I mean. Of course it may well turn out that using individual lights WAS the most effective way to light the scene, knowing my luck, but oh well!:surprised

[fraa]

"with lots of big windows and a skylight" <-
this technically looks like what one usually refer as "cornell box", ie a box without light except a hole with high intensity light going thru.

Imho it won't be as realistic as you expect, unless dealing with expensive render times.
Most of radiosity implementations I tried doesn't seem very happy when it comes to compute a scene without direct light (i'm not an expert though) ... mainly because they will catch either a huge amount of light coming from the window, either no light at all coming from the walls but nothing in between.
Thus you will probably get a really really noisy result, and you will have to ask for a lot of bounces, getting even more cpu intensive.

Well, basically, i agree with Cap' Panic ...
but i'll be glad if you manage to do this your way :)
... simply tell us if it works with a single hdri, and how you managed to do it ... 'just curious :D

[rebeldreams]

D'Oh! I should have realised it was a specialised Cornell Box! :surprised Well, slap me silly, you're right! Of course this will differ in having several ports of entry for the light, but yhe bounce issue is paramount.

Fortunately I have a grunty box with enough oomph to calculate several bounces off surfaces, and I'll keep the geometry simple enough (I hope!) that it won't ramp up render times obscenely. I'll let you all know how it came out, so keep an eye on the WIP section for updates.

Modelling has begun, and I shall post the results soon (initially just an "empty room" solution, followed by textures and then ... drum roll... furniture!)

Thanks for the assist.. and if it looks awful I'll just go with the lights Capn_Panic suggested. Of course with so many windows that may well take as long to get the balance right as an HDRI render will to complete, so I may well be robbing Peter to pay Paul.. well, we'll see.

Thanks again!

~RD

[fraa]

yap ! cornell box is a funny framework to test rendering issues :D
'Just tried what we said above, comparison between two lighting methods :

http://fra.planet-d.net/posts/gi+spot.jpg
the box with a simple shadow mapped spot + indirect illum.

http://fra.planet-d.net/posts/gi_only.jpg
same box, just a high self-illum square and indirect illum with the same settings ...

we can notice articfacts on both images (it's not due to jpeg) but the difference is clear enough :)

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