Ok, stupid question …
I've naturally assumed Houdini could do this since it does deep rasters, but I can't find a good / direct way to say .. for the red channel in the pixel op ..
If ( plane Op_Id array 1 == 3, $R, 0)
Basically, I want to isolate an object by obj id, and I can't find a good way to access or manipulate stuff once it's in a deep raster layer. Is there an equivalent to a point expression for cops. Ideally it would look something like this ..
imgsample(“../node”,$X,$Y,“Op_Id”,0)
How do you read and set values from one image plane into another?? Right now I'm using the channelcopy COP, but looks like all it can do is, well, copy channels :roll:
I think I'm looking at this the wrong way …
Op_Id - extract image plane
27408 31 5- andrewlowell
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Hmm, as to expressions I think they don't support deepraster plates, but I could be wrong.
The point is that Expression COP is pretty slow compared to Vex which additionally gives you access to any plate you want. So I would rather try to avoid expressions and use Vex or Vops.
As to using Op_Id as mattes, you're probably concious of that, but let me just note here that these mattes suffer from artefacts related to pixel filtering similar to issues with Z-depth plates. This method is quite limited in practical usage of selecting pixels on screen.
As far as I know, splitting a scene into layers is much more applicable and error free solution commonly used out there.
The point is that Expression COP is pretty slow compared to Vex which additionally gives you access to any plate you want. So I would rather try to avoid expressions and use Vex or Vops.
As to using Op_Id as mattes, you're probably concious of that, but let me just note here that these mattes suffer from artefacts related to pixel filtering similar to issues with Z-depth plates. This method is quite limited in practical usage of selecting pixels on screen.
As far as I know, splitting a scene into layers is much more applicable and error free solution commonly used out there.
- edward
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As to using Op_Id as mattes, you're probably concious of that, but let me just note here that these mattes suffer from artefacts related to pixel filtering similar to issues with Z-depth plates. This method is quite limited in practical usage of selecting pixels on screen.
Doesn't turning off filtering for these planes work?
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- symek
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edwardAs rdg mentioned the trouble maker is main plate filtering.
Doesn't turning off filtering for these planes work?
I wrote it more like a general note. Sure there are some workaround. Object's Id are around in any application for a 10 years at least since RPF introduction, but I've never heard it's used extensively (not that I refuse their usage at all).
Whatever you do, they won't fit exactly, edges issues. That's why layers are still most popular way of working I think.
What I used to do was to export two ID mattes with minmax min and minmax max filters applied. Then the difference can be used as a mask to tweak edges… But is it really worth of efforts? these ID plates?
It's like a UV mapping in Cops, makes impression, but still makes no sense .
cheers,
sy.
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mandrake0arturmandas
Anything similar on a per material basis? Shop_Id?
you can do it manually.
add to the shop networks (each shader must be modified) a bind export give it a name this case: Shop_Id set a value or export the parameter.
make in mantra a new image plane with the Shop_Id and hit render.
Thank you, yes I know how to do this manually, the reason I wrote is that I am looking for a way to do this automatically…
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