View Full Version : struggling with radiosity

03-17-2003, 08:27 AM
When I render a simple object (a sphere) in a simple scene using radiosity with standard lights or with an HDR image using the Image world plugin, the object renders looking very "noisy". The rendered object looks like it has been put through the pointilize filter in photoshop! I have tried using the reduce noise setting, or whatever it's called and it does quite a good job, but the object loses some of it's surface detail.

I have also tried setting the points per sample for radiosity in the Global Illumination panel (or whatever it's called - sorry I don't have the panel open in front of me) to higher settings, it doesn't seem to make much difference - it just increases rendering times.

Does anyone have some advice as to what I'm doing wrong or how things are usually done. What can I do to improve my results without increasing my rendering times drastically?

03-17-2003, 10:02 AM
try anti-aliasing

03-17-2003, 12:49 PM
that's what Lightwave's radiosity/area shadow is like. The best you can do is use noise shading reduction which simply blurs the shadow. There's nothing you can do until Newtek come up with some more advanced noise reduction techniques.

03-18-2003, 12:27 AM
Anti-aliasing doesn't help much at all. There must be more I can do. I've seen some amazing renders done with radiosity where there is little to no visible noise. There must be someone who can point me in the right direction.

I would really appreciate it if someone could share any general techniques they might have found that give better results when rendering with radiosity.

03-18-2003, 02:59 AM

03-18-2003, 04:49 AM
Turn ON notion blurr.

03-18-2003, 04:51 AM
should be:

turn on motion blur.

03-18-2003, 05:59 AM
U just need to up the radiosity settings, it adds a huge ammount of time to the renders but would look much better. Try increasing the "Rays Per Evaluation".


03-18-2003, 06:19 AM
I just did a couple of test renders to illustrate, i'll have to post them in 2 seperate posts.

Image Info: 640*480, No AA, No Shading Noise Reduction, 1 Spehere, 1 Ground, 1 SkyDome (White, 100% lum).

Image1: Rays: 4*12, Render Time: 80.6 seconds.

03-18-2003, 06:20 AM
Image2: Rays: 9*27, Render Time: 396.1 seconds.

03-18-2003, 06:25 AM
So as u can see, even with no shading noise reduction, putting the rays up by a few settings really improves the quality. With AA and Shading Noise Reduction the second image would look pritty much flawless. But the rendertime is huge.
The amazing radiosity renders u see around the net often take several days to render just that 1 frame but the results can be well worth it.


03-19-2003, 01:08 AM
thanks for the help everyone, especially to SpankDaddy. Whats the weather like in the UK at the moment?

03-19-2003, 02:15 AM
Well its just gone 9 am here and its sunny and bright, but bloody freezing :), theres frost all over and patches of ice.


EDIT: i forgot to say in my other posts, HDRI can often produce some extra grainyness (in both reflections or when using radiosity) so in the image editor panel, add the "Full precision blur" filter to it, this usually helps.

03-19-2003, 03:26 AM
hey spankdaddy where in yorkshire are you? I was born in Leeds,
but now live in leamington spa

03-19-2003, 07:46 AM
That sounds pretty cold SpankDaddy! I'm sitting in a little city called Port Elizabeth in South Africa where it's been unbearably hot. There have been loads of English tourists clogging up all the bars and nightspots, because a few of the world cup cricket matches were played here.

I was in the UK over December/Jan 2002/2003 - boy was it cold! What are the employment opportunities like over there for digital artists? Are there a lot of young creatives floating around, is there a lot of competition?

03-19-2003, 08:06 AM
Just received this - totally unrelated to anything, but it's quite funny!

03-19-2003, 01:45 PM
I was sent that too, very funny, shame the reality is so different,
we could be at war tomorrow.


03-19-2003, 02:18 PM
scottn> lol nice pic.

Matt> Im in Barnsley, so im like 25 mins down the M1 from leeds :)

Btw it really warmed up, was quite nice by dinner time.


03-20-2003, 03:46 PM
apply full precision blur to your hdri image.
there is good information here http://www.newtek.com/products/lightwave/tutorials/fullprecision/index.html
explains where the grainyness comes from etc.
hope this helps...funny pic.

03-23-2003, 11:34 PM
Thanks for the help people, I appreciate it.