Can anyone give me some pointers as to how to do multi-pass rendering in Bryce. There seem to be alot of articles on the net for other apps, but nothing for Bryce and I'm not sure if the different passes would be the same. What would the basic different passes be? I'd really like to have a go at this method of composition.

I believe multi-pass refers to redering in layers... instead of rendering all of the image in one pass it does it in multy-pass...   many passes....  as to exactly what does each pass renders and what does it choose to render ( of the same image) , i don't know...  

I do know that certain calculations are done to render different pixels into imulating certain shades, colors and hues of an image...  not to mention hdr and all the other good stuff renderers do...

Bryce does render in more than one pass as you may already seen....

hope it threw so light...

As far as traditional multi-pass rendering,............Bryce doesn't do that.  I believe you are refering to apps like C4D, Lightwave, 3D Studio Max and the like,..........which may use seperate passes for such things as radiosity calculations, shadow maps, lens effects,  post render  effects and such,.............Bryce does not do this. With bryce you will have to render each layer by itself and composite them in the image editor of your choice(like Photoshop) with Object Mask renders. Hope this is what you are refering to.

Bryce does Object Masks and depth of field masks.

You can create masks, render particular objects with different materials and enviromental attributes and layer them together in Photoshop.
I've posted something similar here:

http://market.renderosity.com/mod/forumpro/showthread.php?thread_id=2659299

(check out Rochrs Cargo ship)

Here are a few examples of MPR not in Bryce, but depending on how well you know your tools, you can achieve similar results.

http://www.rethinkfx.com/tutorials/compmax.htm

http://www.3drender.com/light/compositing/index.html

http://3dny.com/catalog/product_info.php?products_id=28

You can simulate it by making a set of copies from the same scene and isolating channels of materials on them. So one withe verything black except ur specular, one with everything black instead of ur diffuse. one with a light-dome. that kinda thing

render a beauty pass (all materials applied)

render a highlight pass (the model completely black with 100% specularity)

render a "light" pass (the model black, no specularity with any visible lights)

render a reflection pass (increased reflection on the model..it could be a pure mirror or it could be diffuse with increased reflection)

render a shadow pass (crank lights up very bright so as to bleach out the model except for primary shadows)  These may have to be rendered separately if there are multiple lights.

render a mask for the object (just use bryce's mask render)

you then have to composite all of these in a image editor..be it photoshop or after effects..whatever.

Apply each render and adjust the opacity of each until you get the desired effect.  Use the mask render to apply the layers to only the rendered object you are working with,this way you can composite over photos or a select background.

luck

BT

Thanks very much everyone for the info and links .

Bryster, thanks, that was exactly what I was looking for. I'm off to have a go....

Dont forget the light-dome in grayscale! It can give u that GI effect that gives just a little extra dimension to renders sometimes.

Rendering a seperate greyscale light-dome is more economic on rendering speed then adding a light-dome inside your main scene, and it's also easier to tweak in photoshop without need to re-render!

And ofcourse you dont have to lose specular highlights anymore because u can still get those from the key-lights in other render passes

http://www.renderosity.com/mod/gallery/index.php?image_id=407649&member