Newbie Q: RPF, occluded objects and layers

[Anonymous]

Hi All,

I have a simple questions regarding if the RPF format is able to achieve
this:

In my 3dsmax scene, I have 3 objects, A, B and C.
From the camera viewpoint, A is nearest the camera and fully visible.
B is behind and partially blocked by A, and C is behind B and partially blocked
by B. Thats the full 3d scene.

Now I want to render A and C in 1 pass and B in another pass.
Can I render an RPF with just A and C (B hidden)
and then render another RPF with just B (A and C hidden),

And the compositor package (like combustion) would know how to
slot in B between A and C using whatever needed G Buffer info?

Thanks!

[xuefeng xu]

If you render with scanline and enable render occluded for all the objects you should be able to do it all in one pass. If you want to do it in seperate passes then you will need ZDepth for all passes to composite properly.

-Eric

[Adam Redhead]

Hey Pixel Monkey,
I’ve seen your name on the Brazil website so I assume your a max user with Brazil plugin and combustion, which is what I’m using. My question is- For your typical workflow what type files are you using in and out of Max/Combustion (RFP or openEXR) and how are you compositing them in combustion?

Thanks,
Bllibong

[chris]

between max and combustion i’d go 16bit PNG unless you need float, in which case i’d use RPF over EXR. combustion doesnt handle EXR too well (as compared to Toxik).

“MaxBustion” is PNG or RPF in my book.

//gD

[Adam Redhead]

Gary,
Thanks for the info.

Is a 16 png file the same as a 16 bit (half float) as far as having more dynamic range. I like to have a little room for exposure adjustment in case I render a little too dark. I use RPF format because of the extra channels, but I’m curious why PNG as opposed to other 16 bit file types?

Thanks,
Bill

[chris]

16bit png is not the same as 16bit half float. while 65536 total available colors in each RGB channel does provide 281 trillion color as opposed to 8 bit 16.7 million (and thats just a shitload of color to work with for things like depth of field based on grayscale etc), its not float.

when i work in float for combustion, RPF handles it much better. this is a apples and oragnes discussion to the things the RPF G-buffers offer – which are the 3d compositing and 3d post operations.

EXR half float is nice and typically way more color space than i need – but that floating point aspect means a non-destructive color space which is just great for really bright and really dark images (especially things like fire, flares, glows and other really bright things).

//gD

[xuefeng xu]

Do to the way Combustion (and possibly other compositors) handle compositing and alpha channels, I avoid formats that use pre-multiplied alphas (like PNG). No matter what I did I was always getting a halo around my images.

For 8-bit I generally use TGA files, if I need higher dynamic range I would go with EXR. There were some alpha related issues with EXR prior to 4.0.5 so make sure you are up to date.

At this time Brazil doesn’t support layered G-Buffer channels so render occluded won’t work with it. For a ZDepth pass I create a Distance Blend falloff and use that in the Material Ovverride. (See the Brazil 1.2 Guide for generating passes from your Splutterfish Account page for more info on the ZDepth Pass) From there I would create some Scene States and hide objects based on your needs, or from your description just do 1. Use the GBuffer Builder to connect the ZDepth of the images with the other color. Connect the 2 layers into a 3D Composite. From here you need to enable Layer > 3D Depth on both layers.

That should do what you need, if not post some sample images and I, or someone else can throw together a sample CWS for you.

-Eric

[xuefeng xu]

Do to the way Combustion (and possibly other compositors) handle compositing and alpha channels, I avoid formats that use pre-multiplied alphas (like PNG). No matter what I did I was always getting a halo around my images. For 8-bit I generally use TGA files, if I need higher dynamic range I would go with EXR. There were some alpha related issues with EXR prior to 4.0.5 so make sure you are up to date.

At this time Brazil doesn’t support layered G-Buffer channels so render occluded won’t work with it. For a ZDepth pass I create a Distance Blend falloff and use that in the Material Ovverride (See the Brazil 1.2 Guide for generating passes from your Splutterfish Account page for more info on the ZDepth Pass). From there I would create some Scene States and hide objects based on your needs. Use the GBuffer Builder to connect the ZDepth to the already rendered color channel (You will have a GBuffer Builder per layer). Connect the 2 layers into a 3D Composite. From here you need to enable Layer > 3D Depth on both layers.

That should do what you need, if not post some sample images and I, or someone else can throw together a sample CWS for you.

-Eric

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