View Full Version : Radiosity in space????

08-07-2008, 03:40 AM
Would anyone recommend using the radiosity setting in space? I have a rocket that is using a lit explosion and reflection from the smoke/fire and also being lit by the sun. I also have a point light used as a blinking light on the ship as well. Is radiosity really necessary?

08-07-2008, 03:53 AM
Depends on your model. Radiosity works on the principle of bouncing light: Light bounces just as well in space as it does on the earth :) If your ship has fiddly bits or multiple layers, which mean it would benefit from bounce, to light hard-to-light areas, then yes I would reccomend it. If not, then probably not bother.

One other thing I would recommend is if your ship is near a planet (aka earth) then put in a large area light, or light-bounce object to represent it. Or even just have a large polygon with a space photo of the earth, self illuminated, and radiosity on. This will give you some nice soft fill light (which if you look at all near-earth photos, ships do have!) and also give something to reflect, if you decide to use realistic reflective paint finishes (rather than just speculars).

I say test your scene, and work out how long it takes with and without, and look at the difference, and see how it compares, visually. That's the best test.

08-07-2008, 04:00 AM
Thanks for the advice. I notice you said "realistic reflective paint finishes". Is that built into LW or free downloads on the net?

08-07-2008, 04:22 AM
Airwolf do you have a manual? You should try reading it, the answers to most everyone of your questions so far are in it. And get Essential Lightwave, it is a very good book.

08-07-2008, 05:05 AM
Nope, I just mean you make some paint finishes, by fiddling with surfacing and nodes :D It's just a question of tweaking. To be honest there is only so much you can learn from a manual. I have tried reading the surfacing and nodes bit in the manual and GAH it's not very informative The simplest surface would be a high specular, with a high glossiness, and feed a Fresnel maths node (set to 1.5) into the reflection chanel, and push the inverse into the diffuse channel.

you can see some examples of that in the lower half of my portfolio http://www.3dghetto.com/tobian/portfolio/portfolio-1.htm where I use reflection blur in my paint finishes, and not just speculars, and it looks pretty cool! :D

08-07-2008, 09:15 AM
Hey Tobian,
Yeah, that's why I ask questions more then the manual. The manual only gives basic understanding in certain areas but talking with people with the experience and that have done the go around with issues and fresh ideas is the easiest way for me. Plus, I'm sure other people read these forums and learn stuff to.

08-07-2008, 09:39 AM
There are plenty of cases where it makes sense.

As others have mentioned, the object will bounce light around itself in all probability.

If you are near any large object, such as in low Earth orbit, then this will illuminate your spacecraft (or whatever it is). If it's not in view this is often easily and rapidly faked with a soft blue spotlight at low intensity from the required direction.

The most extreme example I know of can be seen in a few shots of Saturn taken from behind the planet, (i.e. on the side away from the Sun). The light will bounce off the rings back at the unlit side of the planet in a complex manner not easily faked with lights. (For example, the rings are edge on from Saturn's equator, and cast no light back, and are not visible from near the poles).

Closer to home, when the moon is a thin crescent in the evening sky you can often see the 'dark' part faintly with your own eyes. This is sometimes called the new Moon in the old Moon's arms, and is caused by light bouncing off the Earth to illuminate the moon.

08-07-2008, 04:33 PM
Another quick way to add that kind of faked fill light, if you have radiosity enabled, is to just paint a blue-ish circle on a small image, and use that as your 'textured environment'. Very small and soft images in the environment don't add too heavilly to render times, or make speckly renders.