rgb values to integer values conversion possibility..

[lalamax3d]

there are almost 5 thread about topic (little variation) few are little helpful., but in true context, problem remains and exist, so i finally decided to ask and get this solved for myself and others here...

tools using (3dsmax / mental ray and nuke)

BIGGEST QUESTION:
1- is it possible to have ID's pass as integer values but "antialiased" from 3d app
2- is it possible to convert RGB image to Interger values, in nuke.

CURRENT WORKFLOW:
in 3dsmax:
when rendering EXR, it gave me option to embed id's inside exr, when i see details, it is called "mono" for encoding option, this is where HUGO gizmo works, except anti-aliasing option doesn't help much..

if i enable render elements separately, then it created rgb image. it seems best "anti aliased" but HUGO gizmo doesn't work here.
how can i convert my id's (rgb) image to INTEGER values. inside nuke??

[alkali]

1) No.
2) You don't want to do that.

Render RGB mask passes.

[Void]

Think about the motion blur, man... The motion blur!

[lalamax3d]

alkali: i'll check rgb mask passes..
VOID: what motion blur has to do with this..?? didn't get that. motion blur needs vectors for motion, that are stored in separate motion / velocity element or pass..

[forkazoo]

I think Void means that a motion blurred ID pass is impossible.

[Paradoc]

I always found it easy to use a Renderlayer (Maya) / Material override (Max) with simple unshaded materials where each ID or object has its own color (thus RGB value). This gives you the exact same anti-aliasing, transparency, DOF and motionblur as the master render because the only difference is the color. It's kind of a failsafe way to go.

In Nuke, I guess this should get you going with that Hugo gizmo you speak of. If you need to tweak the pass with grading to fit Hugo's way of working, be careful that you keep the edge falloff the same by using the correct black and white points.

[beaker]

Render RGB mask passes.

Even RGB passes are a waste. 3d applications can easily render objects do separate arbitrary exr layers. Most of the time I have an exr with a 100+ of them all named properly. With RGB masks your limited on your naming which makes it very hard to find different object masks when you have lots of them.

[Hugh]

Even RGB passes are a waste. 3d applications can easily render objects do separate arbitrary exr layers. Most of the time I have an exr with a 100+ of them all named properly. With RGB masks your limited on your naming which makes it very hard to find different object masks when you have lots of them.

I can only assume that you and he did actually mean the same thing - make sure that each object has its own channel.

If you're worried about disk space (the OP, that is, not Beaker), compressed (losslessly) EXRs can be very efficient when doing matte channels - I've seen 2k, RGB EXRs with different mattes in each channel get down to in the region of 30-100kb each.

[beaker]

No, RGB mattes means you put the mattes as Red, Green, Blue. Unless your working on flame, that is a bad way to store things because your limited to a single name per layer. If you have lots of mattes, this makes it a giant pita to organize thing. For example you would have to name it: Head.r, Head.g, Head.b, Body.r, Body.g, Body.b, etc...so your naming is very limiting. A much more efficient way is simply writing everything to alphas. So Head.a, Body.a, Hand.a, etc...

[Hugh]

Sure - I get what it should mean. But to a lot of people, they just differentiate between RGB mattes (where different channels contain different objects) and an ID pass (Where different values correspond to different objects). What we're generally saying is ideal is closer to RGB mattes than an ID pass, with the added ability to have as many channels as you want.

How you decide to name the channels is a challenge unto itself - you might want to, as you suggest, just put each one into the alpha for the layer. You might want to name the channel something like "matte" (so head.matte, body.matte, hand.matte), or you might want to group them together (so person1.head, person1.body, person1.hands, person1.feet)

[alkali]

Even RGB passes are a waste. 3d applications can easily render objects do separate arbitrary exr layers. Most of the time I have an exr with a 100+ of them all named properly. With RGB masks your limited on your naming which makes it very hard to find different object masks when you have lots of them.

"RGB mask passes" is a generic way of saying "render solid mattes for your objects so you get proper AA." What you do with them is your choice, but that's about the least complex way I could come up with to get my point across.

In reality, your workflow is exactly what I would do: pack arbitrary mattes into a single EXR sequence (although depending on what kind of storage system you have, scanline requests from a 100 layer EXR could be cumbersome).

[beaker]

"RGB mask passes" is a generic way of saying "render solid mattes for your objects so you get proper AA."

Right but every 3d person I ask for RGB masks gives me masks in the rgb channels so I usually need to be specific that I want actual masks in an exr file not an exr full rgb channels which happen to be masks.

scanline requests from a 100 layer EXR could be cumbersome

with bbox's they compress down to around 10 meg a frame. So very little hit.

[alkali]

Yeah, that's understandable. I typically work on both sides of the fence, so when I ask myself for masks, I'm already pretty clear about what I want. But like Hugh mentioned, when differentiating between ID passes and mask passes, the masks would fall much closer to the realm of RGB masks than IDs...