Hi all
I’ve tried various elements to be able to “select objects” in post and change it’s colour. However each of these 3 render elements gives me same results: VRayMtlID, VRObjectID, VRayRenderID
The render is nicely anti-aliased, but any of the above 3 elements are “solid” pixels at the edges ie Aliased. So the result is that if you pick your object in post and change the colour, it gives “ghosting” or “mess up” the edges.
How to overcome this?
You can use the Multimatte render element, or the VRayWireColor one. You can also use the VRayObjectSelect element in a similar way.
Best regards,
Vlado
Where can I get information on the parameters of each of these (what the settings in each element does)?
multimatte just renders blank for me. wirecolor seems promising so far… more testing to be done
that doesnt tell me anything
Sorry. For Multimatte you have to set your either objectID or material ID and then set the correpsponding R, G or B number to that ID number (and also ensure the checkmark is on for that color). In addtion if you are using matID rather than objectID you have to check the MatID button at the bottom. I’ve never used it but the VrayObjectSelect looks to work in a similar way but actual renders the image rather than just a mask like multimatte.
Which one can I use to render a meterial ID on its own layer? VrayObjectSelect works almost, but the colour is slightly different in “Normal” mode. In “Raw” mode it also renders a filter layer and also a alpha layer which seems to complicate it too much. All I want is to render a specific material on its own layer, that way I don’t even have to select it in photoshop, just adjust the whole layer. Is that too much to ask for?
VRayMtlSelect also seems to change the colour
NEVERMIND: Forgot to click “Color Mapping”
I still think your best option is multimatte (or the alpha from objectselect) and using that as a mask in photoshop. Since the object is rendered over black for ObjectSelect you could have problems in photoshop when trying to use the alpha as a mask due to edge artifacts (i.e., black edges). Using a mask on an adjustment layer should not exhibit these artifacts because the black edges just aren’t there.
I dont understand why the multimatte has an R or B or G you should select. All it does is a mask so how does one of the RGB things help? Do you get different results depending of which one you of the R or B or G you choose?
That is the channel the mask is stored into. By using R/G/B you can store 3 mattes per renderelement. Without the issues all other options give you. As the channels are completely seperate you get a perfect matte.
Regards,
Thorsten
so if I understand you correctly, I could store my “door, table and floor” in one renderelement in different channels r = door, g = table, b = floor? All those will be in one element coming up as 3 different colours?
Then I need to create another multimatte element for my “chair, bed” etc.
Then I could use the r or b or g as a mask?
Exactly. The ObjSelect uses the same selection methology (MatIDs ir ObjIDs) but stores one selection per matte, but the final RGB pass of that ibject (unpremultiplied when set to rawmode) and along with an alpha element
so then if I occupy all 3 channels r and g and b in one channel, can I split them afterwards or does this mean those 3 objects will always be edited together?
Yes you can. That’s the whole Point. In PS for example you can simply copy the channel to be a mask for a layer or a selection and it will be Pixelperfect
If you need a lot of masks for a lot of objects you can use my MME generator to build the render elements and assign the object ID’s here.
ah ok so I dont use the selection tool in photoshop, but the actual red, green or blue channel in photoshop, I then use that channel as the mask on my layer?
I take it that it is similar process if it is an animation and I use AE or Combustion or Composite or Nuke or any of those?
is that correct?
Exactly. Sorry. My earlier reply got lost.
thanks all for your help
Instinct: The multimatte worked great, will be using it on every project now 
dlparisi: after working 100 miles an hour, I somehow missed your post about your multimatte script, thanks I will take a look