Forum: Bryce


Subject: True Ambience/Global Illumination

rbanzai opened this issue on Aug 06, 2001 ยท 11 posts


rbanzai posted Mon, 06 August 2001 at 1:22 PM

In the manual they refer to True Ambience as a color-bleed feature, kind of like radiosity. To test I put a red sphere in front of a white wall and enabled the feature. I noticed that the colors of things did indeed seem to change but there was no red on the white wall like with radiosity. Is there something I need to do to get this effect other than playing with color lights and shadows? Thanks


Deathbringer posted Mon, 06 August 2001 at 1:40 PM

Not sure what your settings are for the wall but you might try turning up the reflection of it, and making sure it has the option to except shadows from other objects. Maybe post the image for me to look at and that might help... Good luck


Deathbringer posted Mon, 06 August 2001 at 1:46 PM

I just got my manual out.. I assume you are rendering it in the premium mode to get that effect to work??


rbanzai posted Mon, 06 August 2001 at 1:49 PM

Attached Link: http://www.bryce5.net/gallerybrowseshow.asp?PHOTOID=78

Yes I am. Here is a link to a place with an image rendered with "global illumination." There is no way for me to contact the artist to ask him what exactly he means. P.S. I am not new to Bryce, been using it since version two. http://www.bryce5.net/gallerybrowseshow.asp?PHOTOID=78

Deathbringer posted Mon, 06 August 2001 at 2:34 PM

Man that term is defined in the manual, but if you look at page 194-196 they talk about the "global" things of Bryce.. The only one I can think that he might be refering to is the "global changes" (right middle column, page 194) It says "The component window in the center of the editor, called the Combination component, represents the final combined texture. Any changes you make to this final component are considered global changes since they affect the entire texture" Not being at home its hard for me to test things out and all I have is my manual and books here that I read..over and over and over..:) Hope that helps you some.


rockjockjared posted Mon, 06 August 2001 at 3:54 PM

The only way that I could get "global lighting" to work was by faking it...setting up a LARGE amount of spotlights around an object and then playing with the light levels...but I have never been able to get the results that I have wanted. Jared


PJF posted Mon, 06 August 2001 at 6:33 PM

The key word is 'ambience'. As far as I can tell, this feature only works for materials with the ambience level activated. To get an object to appear to cast light onto another object, both objects must have materials with some ambience level. The light that is cast comes only from the ambient aspect of a material - not from 'bounced' light from its diffuse channel. Only the ambient aspect of the 'receptor' object's material is affected by 'true ambience'. In the image, sunlight has been disabled and the sun colour set to black. There are no diffuse colours in the materials, and there are no lights in the scene. The light being cast onto the floor comes from the ambient materials of the wall and sphere. The light being cast onto the top of the sphere comes from a brighter yellow object just out of view. The most obvious affect is from lighter colours onto darker colours, but only down to a certain darkness level - very dark or black doesn't appear to receive light at all. The light that appears to be cast from 'light' colours is realistic in its fall off rate. Looking at the image, you'd think that the darker colours were having no affect on the lighter colours at all. This is because their fall off rate seems to be very slight. The wall and ball are darkened slightly by the presence of the dark floor. It's almost as if the fall off rate for light colours onto dark colours is squared with distance (as with real light), while the rate for darker onto lighter seems linear with distance. I find the effect far too limited to be of any real use. In Bryce4, I'd have simulated the 'radiosity' with lights (positive, negative and coloured) and the scene would be more realistic and would have rendered faster. This is another quirky Bryce trick that someone, somewhere will find useful occasionally. The rest of us will fiddle with it to see what it does, baulk at the render overhead, and move onto something more practical. I'm not aware of there being a global illumination feature in Bryce5. The image in the link provided by rbanzai is rendered in Bryce4 I believe. 'blueba' put up a whole series of Bryce4 'trick' renders to show what could be achieved by simulation methods.

rbanzai posted Tue, 07 August 2001 at 10:34 AM

Thank you for your help and your excellent demonstration. Like a previous poster a couple of weeks ago this seems to be more of a "glow" feature than anything else, and if glowing light was needed it might be more realistic using "True Ambience" than other methods. Other than that it seems limited. I will wait and see though because Bryce-ians come up with so many clever uses for their tools.


griggs posted Tue, 07 August 2001 at 4:23 PM

Hia rbanzai you are so right about not taking things at first glance in bryce. I used ambient light set up to do this image. With True ambience off this image is almost pure black but with it on :) Check it out it was rendered with 1 light in Bryce 5. Looks pretty convincing to me. Griggs

PJF posted Tue, 07 August 2001 at 6:52 PM

Hmmm, Griggs has made me investigate further; so now I'm eating my words (the git ;-)). There is a kind of global illumination available via 'true ambience', and it looks like being a very powerful tool indeed. Damned annoyed I have to go to bed now! :-D


griggs posted Tue, 07 August 2001 at 6:59 PM

it is indeed PJF will post something to see in just a little while. Griggs