Ability to export a seperate matte for each object id?

[joconnell]

Hi Folks,

I've just started using the vray frame buffer and render passes and more speciifically the object id channel - it looks like a really handy way that I can pass a lot of object mattes down to the flame op here and I was just wondering would it be possible to rather than having a unique colour for each of the object ids, would it be possible to get vray to output a white and black matte channel for each object id instead? It's be much handier than trying to key each colour to get each channel. I don't use object ids all that often so it could be me doing something quite daft - any thoughts on this?

[studioDIM]

it *should* be possible to script a render effect that does just that.

I'll try looking into it later on (tonite/tomorrow).

No transparency would come out though, but i guess you know that already


Lele

[joconnell]

Hmm - would it render with the same camera motion blur as vray though?

[studioDIM]

my guestimation is that it would work as a POST effect.
Ie. taking the rendered objID, and copying each different id into a new BW image.
IF it worked like that, it would surely take into account the moblur/DoF when done in camera.

You might, though, try and script something comp-side.
Shake, or even DF might do the same job on an objID layer.
Wouldn't know about Flame, but if combustion is anything to go by, it's going to be hard-ish.

Lele

[joconnell]

Ah yes getcha now - Just have to figure out what way maxscript has access to object id channels.

[mike.edel]

seems its accessible by maxscript since max8:

Object_ID : RenderElement
Object_ID - superclass: RenderElement; super-superclass:MAXWrapper - 5:0 - classID: #(21, 0)

NEW in 3ds Max 8: The Object_ID RenderElement outputs the Object IDs assigned to objects via the Object Properties dialog.

Note:

This RenderElement is not available in Autodesk VIZ.

Constructor

Object_ID ...

objectIDRenderElement ...

Properties

<Object_ID>.bitmap UndefinedClass default: undefined -- bitmap;

Gets the bitmap the RenderElement writes to.

<Object_ID>.colorMode Integer default: 1 -- integer; Object_ID

Gets/Sets the color mode.

Possible values are:

0 - Object Color

1 - Object ID

<Object_ID>.elementName String default: "Object ID" -- string

Gets/Sets the name of the RenderElement.

<Object_ID>.enabled BooleanClass default: true -- boolean

Enables/Disables the RenderElement.

<Object_ID>.filterOn BooleanClass default: false -- boolean; FilteringOn

Enables/Disables filtering for the RenderElement.

[joconnell]

Cheers for that Mike - I wonder does vray use the same methods? I'll look into that later this evening when i'm less hungover

[studioDIM]

I was looking into the algorithm to use to achieve that, and just noticed that the objID is not taking into account moblur...
So you'd get a wrong type of alpha as output.

Maybe it's just me, but that's how it looks rendering from either Vray's framebuffer or max's own.

Lele