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AdamAvenali
09-15-2005, 03:15 PM
I was just wondering if there was a way to kind of fake radiosity with a special light setup or something? I really like the way that the shadows are rendered with the radiosity, but I usually have a short deadline, so I cannot afford the render time for each frame.

I am really only using this for rendering 360 degree views of my character models, so there are no camera moves or anything to that effect.

Any help is greatly appreciated!

Adam

papou
09-15-2005, 03:33 PM
try to find some info about 'Spinning Light' technique.
ciao

ericsmith
09-15-2005, 03:35 PM
Area lights can get you most of the way there.

I usually try to look at the scene, and figure out what major radiosity light sources there are, like sky, ground, large walls, and then use area lights to mimic that bounced light. If you break up your scene to seperate these components, you can have the area light that is simultating the radiance from each component ignore the component itself, so you don't get blown out lighting.

Eric

Limbus
09-15-2005, 03:42 PM
Spinning lights was allready mentioned but you might also want to search on light dome and ambient occlusion.
And check out Overcaster which is part of Ekis Plugpak:
http://www.kolumbus.fi/erkki.halkka/plugpak/

Florian

FIREGIRL
09-15-2005, 04:13 PM
I was just wondering if there was a way to kind of fake radiosity with a special light setup or something? I really like the way that the shadows are rendered with the radiosity, but I usually have a short deadline, so I cannot afford the render time for each frame.

I am really only using this for rendering 360 degree views of my character models, so there are no camera moves or anything to that effect.

Any help is greatly appreciated!

Adam

Try surface baker. It works wonders for deadlines because it allows you to bake in true radiosity (and you only need to render radiosity once). http://www.newtek.com/products/lightwave/tutorials/rendering/lw_baker/lw_baker_cow.html

I'm not sure how it will go with 360 degree views however, since the shadows have been stuck to the model's UV's -- you might want to render under neutral light conditions, thus preventing heavy contrast (allows for baked surfaces to receive a balanced shading distribution when viewed in 360 degrees). Anyways, hope that helps. :thumbsup:

-Rachel :lwicon:

marble_sheep
09-15-2005, 04:28 PM
The problem with baking your surfaces is that surface baking takes forever. So, you should evaluate on a project-to-project basis as to whether it is actually faster. I think your best bet is to try some of the techniques listed above, such as the Spinning Light Trick. If you're doing a single model in an empty setting, there is little need for true radiosity.

OR... you could buy fPrime. After using it, I can't imagine being without it again! :thumbsup:

FIREGIRL
09-15-2005, 05:36 PM
I gotta agree with you there lol. Surface baking does take forever especially when trying to bake in true radiosity itself. I have tried it and the baking procedure, although not very tedious, requires patience ugh! So I guess Spinning Lights is the way to go for now if users don't have Fprime at their disposal.

SeduceandRob, if you want a good lighting setup for true radiosity just turn off all your lights (including ambient intensity under global illumination) and use an illuminated dome (with a texture if you want -- eq. a sky texture) surrounding your character and a ground to support it. The dome must be 100 percent illuminated with zero diffuse. This dome will be used as the light source. You can shorten the render time by utilizing a sphere instead of a dome, and then removing the ground as this will reduce the amount of bounces. In the radiosity rays per evaluation, choose 6 X 18 rays; this allows for quicker calculations but still retaining fairly good quality of your renders.

Now you said you wanted to display your character in angles around a 360 degree view. So I take it that you will not try to animate this but instead, just have several stills from different angles. I would estimate that you would have to render about 4 stills; each angle will cover each side of the 360 degree cubic proximity. Since it is only 4 stills (at least to my estimation), then rendering with true radiosity wouldn't be so heavy unless you plan to render more than one character in a single frame.

But if you wish to speed up true radiosity, then exclude the ground. If you want to get an even distribution of light upon the character, make sure that if your light sphere is textured or has a gradient, that the brightest and darkest areas of the color map are distributed equally throughout the surface of the sphere.

Aside from that, if those things are too time consuming, then I guess your best option would be to use the Spinning Lights trick of which others have mentioned prior. Oh and good luck. :agree:

One more thing, you can also try Imageworld. Although this isn't as flexible as other methods, it may still increase the realism of your renders because, just like an environmental textured sphere, it allows Lightwave to calculate the light information from a photograph.

-Rachel D.

toby
09-15-2005, 11:03 PM
I think he did want to do an animated 360... for that, I think I'd try baking, or maybe a combination - the ground plane could be baked easily, but use a camera pointed straight down, then project the texture back on with the same camera. This way you can use the native renderer which is much faster. Backdrop radiosity is much faster than real radiosity, and looks pretty dam* good, so I'd use that for the model, first trying baking... but you might be able to get reasonable times rendering every frame too. And you don't *have* to render 360 frames, you can cheat it to 300 :)

AdamAvenali
09-16-2005, 08:29 AM
Thanks everyone for your input, and in such a timely fashion! I definitely have some ideas to work with now! :thumbsup:

duke
09-16-2005, 08:55 AM
Search for any of Gerardo's posts on cgtalk and here. The ambocc plugin for the most part takes care of the light distribution, but it does nothing for light bleeding/bouncing, so a combination of ambient occlusion and techniques to simulate light bounce/colour bleeding is a good option. See Gerardo's threads on "bounce effects with gradients", and look into fi_localambient. You can then use the added capability of having ambient-only lights simulated by using nulls and a gradient in the localambient plugin and applying the technique mentioned here:

http://www.cgarchitect.com/resources/tutorials/smoke3d/tutorial9.asp