radiosity and rendering

[kcy88]

I have a question.
If i use radiosity w/ photometric lighting to render one of my scenes and animate a character, will it calculate radiosity for each frame since the character will be moving? I know that it doesnt recalculate the radiosity solution if you move the camera around, but what happens when you move objects? I haven't had the time to test render the animation since we haven't finished our character rigging.

-kevin
team 75
www.roboraiders.com

[Bduggan04]

This is straight form the 3ds max 5 manual, and it holds true for six:

Object Animation
The radiosity solution is calculated for each frame if any object is animated in the scene (the default is to calculate the current frame only). You specify the parameters (goals/quality) you want to reach in the Advanced Lighting dialog. It is recommended to run a solution first and verify if it’s successful before proceeding to the whole animation. These parameters will then be reprocessed for each frame.

You go to the render dialog, Common Parameters rollout, and enable the option Compute Advanced Lighting When Required, and then render the scene. The radiosity is processed for the first frame and then rendered. 3ds max then moves to the next frame, processes radiosity, renders, and so on.

Hope this is sufficient.

[Matt Hallock]

Yes, it will recalculate every time because the light is being re-emitted off of the moving object each frame.

[kcy88]

hmm.. thanks alot.

[rowe]

a quick note about radiosity, i would tend not to use it for videos, becuase it takes way too long and it will not improve the quality THAT much. radiosity is good for stills, where detail is not lost due to either the quick animation (it stays still so you can take it all in) and/or compression. in my opinion, unless you have an extremely fast computer (not pc, im talking like a supercomputer) or a renderfarm, using radiosity would be very impractical

[Matt Hallock]

I run on a Athlon XP 1800+ (Overclocked to 2 Ghz) and the radiosity calculation time, even for very complex rooms, takes maybe 30 seconds to a minute. However, he's correct, if you're computer is slow, say below 1400, I'd not even bother with it.

[av11d]

We're using top of the line P4 laptops with high end mobile video cards. Radiosity does take a bit, but our longest shot contains no animated objects, only a moving camera, so radiosity shouldn't be too much of a problem.

[Matt Hallock]

If it's P4 it isn't top of the line, I've used both in their supposed equivilants, AMD is usually 25-35% faster in calculating and rendering.

[Lev]

If it's P4 it isn't top of the line, I've used both in their supposed equivilants, AMD is usually 25-35% faster in calculating and rendering.

Not in 3dsmax. newer P4s outperform Athlon XPs by a lot, and are still faster than new Athlon64s by 5-10% (in most cases)

[kcy88]

Our current radiosity settings:
Initial Solution: 50%
Iterations (all objects) 1

Raytrace GLobal settings:
max depth: 3
---

I've been able to decrease the render time to 5-6 mins when it calculates radiosity. THe scene has about 205 objects. I'm satisfied with the current results, but if anyone has suggestions please speak out. :p

I don't think render time will be too much of a problem since we aren't using it for the entire animation. We're only planning on using radiosity in the first 10-15 secs, then switching over to light tracer.

How is everyone else's animation coming along?

-kevin
team 75
www.roboraiders.com

[rowe]

ok, if youre using radiosity at that quality (50%), it shouldnt be a problem, but the time increases expodentially so it want, say, a 90% solution or higher, it can take quite a long time. good luck with everyones animation.

[Matt Hallock]

Not in 3dsmax. newer P4s outperform Athlon XPs by a lot, and are still faster than new Athlon64s by 5-10% (in most cases)

http://www.anandtech.com/cpu/showdoc.html?i=1946&p=6

If I find the CGtalk article I will, a guy was using a P4 against his Athlon XP. The XP came out on top. That link there shows that the A64 is faster, albeit slightly, than the 3.2 GHZ P4EE.

[kcy88]

ugh...
its whenever i render, it keeps recalculating radiosity! why?
omg.
i'm pretty sure no objects are moving, except the camera.

[Matt Hallock]

It's looking at it from a different angle each time, all renderers (Atleast ones that use some form of indirect illumination and sub-surface scattering) recalculate what they do each time.