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View Full Version : Luxigon Dome Light with "fake" HDRI from "Fisheye" Advanced Camera



Andrewstopheles
12-22-2008, 08:56 PM
I am re-opening an old scene that needs a lot of lighting work. I could benefit from some input if anyone out there is willing to offer some advice. I have two main questions, as follows:

Question #1:

Can this be done?:

Render a high quality image with intense lights using fisheye lens to create a "fake" HDRI image and then illuminate the same scene with Image World with that image while turning all the other lights off.
Maybe this doesn't make sense?
I do not want to bake all the objects (it's a fairly large scene with lots of objects) although that's what I did previously with this scene

Question #2:


What is a good starting point, or what would be the generally accepted approach to lighting interior (Architectural) scenes? I've looked around the forum and found bits and pieces but couldn't find a general "all-around" explanation.

I am aware of the many issues with the lights used in this render (I was experimenting with different light types) This just happens to be the best shot to show what is in the scene. I am not looking for ways to improve it - I am looking for a better starting point from which to proceed.
Any advice would be appreciated, thanks!

Thomas M.
12-23-2008, 01:58 AM
You wouldn't use the fisheye, but the advanced camera rendering out a 360 spherical panorama as a hdr. file. But remember that lightsources by themselves aren't visible. You'll need a luminous polygon. But you wouldn't bake small light sources into a hdr. anyway. These won't render nicely and will have a noisy image as a consequence.

gerardstrada
12-25-2008, 05:01 PM
Though they are excellent for outdoors scenes, IBL light rigs are not very handy for speeding up indoors lighting (though they can be used for simulating luminous polygons effectively in faster times and avoid noisy results already mentioned by Thomas).

There are hybrid techniques to speed up indoors illumination by even using MC/FG. The trick is to place lights strategically. There's an excellent tutorial by Otacon (http://www.3dtotal.com/team/tutorials/po_diner/diner.asp) about this. It's a bit old but principles are applicable with new LW GI and results are better and a lot faster now.

By doing this in the right way, is possible also to not use MC or FG. But this implies to simulate indirect illumination in some way. There is a scene called QuickRoom in v9.3 Content shared by Jean-Marc Labal which makes a proper use of area lights. If you think the result lacks for indirect lighting, you may want to try to add the bounce light effect in post (http://forums.cgsociety.org/showthread.php?f=21&t=471102). That trick works for a second bounce effect as well. Other hybrid techniques make usage of AO passes instead of area lights (which is quicker) and bounce lights (or gradients (http://www.hdri3d.com/xtra/11estrada/index.htm)) for simulating indirect lighting.



Gerardo

toby
12-26-2008, 01:42 AM
I am re-opening an old scene that needs a lot of lighting work. I could benefit from some input if anyone out there is willing to offer some advice. I have two main questions, as follows:

Question #1:

Can this be done?:

Render a high quality image with intense lights using fisheye lens to create a "fake" HDRI image and then illuminate the same scene with Image World with that image while turning all the other lights off.
Maybe this doesn't make sense?
I do not want to bake all the objects (it's a fairly large scene with lots of objects) although that's what I did previously with this scene

Question #2:


What is a good starting point, or what would be the generally accepted approach to lighting interior (Architectural) scenes? I've looked around the forum and found bits and pieces but couldn't find a general "all-around" explanation.

I am aware of the many issues with the lights used in this render (I was experimenting with different light types) This just happens to be the best shot to show what is in the scene. I am not looking for ways to improve it - I am looking for a better starting point from which to proceed.
Any advice would be appreciated, thanks!
HDR's don't help very much with interior lighting, most of it gets blocked out by the walls.

I'd think you'd want to start with what light fixtures there are in the room, then add radiosity, then add lights if there's dark areas. If it's too dark overall, raise the exposure of the rendered image ( you must render to .exr for this ).

Instead of baking, in LW9.5 you can now bake all the radiosity lighting to a cache, and as long as the lighting doesn't change you'll never have to calculate it again.

*Pete*
12-26-2008, 03:12 AM
answer for question 2:

light the scene as well as you can without using GI first.
add (area) lights that simulate the sky outside the windows with a falloff.
add a (area, sphere) sun light to act as the sun.
add a (area) light under the floor, shadows off, falloff and a color close to the color of your floor surface, potentially the same with the ceiling to simulate bounced, diffuse light.

then turn on GI..preferably at a low intensity to brighten up just a little and to smooth out the contrast.

you can also add lights to fake the bounced sunlight where the sun hits the room, but this is personal taste.

the idea is however to light as much as you can without GI...it will not only save render time, but also look more natural and allow for more controll.

Andrewstopheles
01-06-2009, 06:02 PM
Thanks Thomas, Gerard, Toby and Pete for the suggestions.
I tried a bunch of different ways of lighting the scene and found that what you suggested works best.