Going back through a whole load of posts here (prompted by pumeco's announcement of his 'PRO-RENDER'), it occurred to me that I haven't actually specified what it is that I've been going on about with True Ambience. I've presented everything obliquely, but not actually spelled it out. I apologise for this oversight, but it's not as if I've been selfishly making amazing pics with 'my' knowledge, or anything - I just didn't get organised. Anyway, here goes. What I found was that it was best to turn the concept of Bryce 'ambience' completely on its head. Under the normal render settings, a Bryce material that has some ambience will appear to be lit by itself - it is illuminated whether there is an external light source or not. Taken to the maximum setting, it will appear to glow (with no effect on its surroundings). I always hated the unrealistic appearance of ambient materials, and avoided them at all costs - preferring to use multiple lights to provide 'fill'. However, messing about in the depths of the True Ambience feature eventually led to a realisation. The True Ambience setting can treat ambient materials in a completely different way to normal. I reckon the best way to think of how materials interact in the way I use True Ambience is like this: - Diffuse materials act as diffuse 'reflectors' of light. - Ambient materials act initially as 'receivers' of this diffuse light, and subsequently as both 'reflectors' and 'receivers'. The absolute key to how this works (bizarrely enough) is to enable ambience in all individual materials but disable all ambience overall by way of the sky settings (set 'ambient color' to black under the 'shadows' window). In a normal render this will result in no ambience. Under True Ambience, this will result in, effectively, radiosity. Under this variation of True Ambience, a light shone onto a diffuse material will illuminate that material as normal. However, that diffuse material will now also act as a diffuse illuminator upon the ambient channel of any material. It will act upon those ambient channels whilst taking into account any obstruction by objects. It will act with appropriate light falloff. Any ambient channel thus lit will now act similarly upon any ambient channel, again taking into account obstruction and light falloff. And so on. This is as close as Bryce gets to the automatic 'bouncing' of diffuse light - and it's bloody amazing. For realism, the ambient channel of materials should be set to the same colour as the diffuse channel; and (as a starting point) the ambient channel should be set at 60 (diffuse 100). The sky dome also acts as a diffuse illuminator. Unfortunately, this method is flawed for reasons I've mentioned previously. Mesh objects do not smooth under 'ambient' light. Some primitives (the cube!) do act consistently under 'ambient' light (one side brighter than the other; light 'leaking'). The result of Bryce booleans fails to respond to 'ambient' light properly. Transparency doesn't work properly under 'ambient' light. These problems are a real shame, because without them this would amount to a render feature for fantastic realism. Hopefully pumeco's 'PRO-RENDER' will live up to the hype and overcome these limitations, and we'll all be knocking out photorealism with no downsides. This should give you something to chew on in the meantime. (BTW, it's gone 2am here, and I've probably forgotten something important (no proofing!). I'll look in tomorrow and answer any questions)

By way of illustration, here's a collection of Bryce primitives lit only by the Bryce sun. The primitives have materials set in my True Ambience mode as I've described above. Premium effects are enabled at 144 rays - but only soft shadows are engaged **not True Ambience**. All sky settings are black. The only light is the sun. The result is a typical raytrace render. Any surface (or part thereof) hit directly by a light (in this case, the sun) is illuminated, everything else isn't. Rendertime approx eight and a half mins. Note the objects lurking in the shadows at the back of the big cube.

This is exactly the same scene, except I've enabled True Ambience - the only difference. This is a very different story. Much more realism from just one light. Note how the objects at the back are now illuminated, mostly from diffuse reflection from the ground plane. Note especially how the little cube at the back picks up the red from the adjacent cylinder. That is a tertiary bounce. This is 'radiosity'. Not by strict definition, and not perfect. Render time? Approx fourteen minutes.

Ooh, another thing. Obviously with the overall ambient colour set to black, no ambient materials will glow. This is a problem if you want glowey objects. The fix is to use simple volume materials. And, not only will the objects glow like a normal ambient material - they will actually cast light on the surroundings! When I say simple volume materials, I mean it. Use flat shading only. Basic shading or full shading will freeze/crash Bryce. G'night!

nice,definately a bookmark.

Layman question... I see the red on the back cube... but why doesn't the big cube pick up any of the red or yellow from the other objects?

Muddy: I can see the red and yellow reflected on the big cube on my monitor (and on the ground, as well). Maybe your monitor is set a bit dark.

I see it as well,check your calibration.

"set 'ambient color' to black under the 'shadows' window" So THAT's the secret! thanx!! that's what I've been doing wrong...

Thanks tjohn & Bolt. A minor adjustment and I can see it.

This is what I hoped you would do when you first brought it up PJF, so thank you for finally reading my mind. 8)

Hi PJF, Just spotted this thread, and thought I'd pop in for a nosey peek. It's great that you've decided to explain this sort of thing in great detail, hopefully novices will get on the bandwagon as well as the power users. Great stuff, I just know I'm going to love looking through the threads here, I will look at them all sooner or later. Thanks for your comments and advice, I think we're gonna have some seriously interesting chats in the future! Respect!

I should point out that some of the stuff I was doing in earlier threads was different to this. This method evolved out of those. Hey, I'm no power user, just a curious fiddler. There's a lot of areas of Bryce where I'm still a novice. I Don't think I've ever touched any animation controls apart from the 'Delete All Keyframes' easter egg!

Thanks for this PJF (and good to see you back, pumeco). At some point when my PC has a few days of spare CPU time, I'll definitely have to look into this sort of stuff (my absolute novice area - along with typing it seems.).

Message edited on: 06/28/2004 20:01

Just a little advice, DON'T use true ambience with metaballs! Ouch what a render time hit! My metaball human renders in about 8 minutes normal. Turned on true ambience and plop rendered the nose.....over 1 hour for the first pass esimate just for that small section!

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