Author Topic: Render clown pass only?  (Read 4186 times)

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Offline mattjgerard

Render clown pass only?
« on: August 15, 2017, 10:48:24 am »
Hey all ! Is there a way to render just a single pass from the render pass selection, and not the rgb composite image? Some times I need to apply a similar material to several objects to create a mask in PS for some effects, and so far I've been doing this by just rendering out they whole thing at 5 seconds or 5 samples just to get the clown pass to render. Would be neat if there was a way to just shoot out the clown without rendering out the RGB too.

Is there a way to do that? I'm diving into render layers as well to accomplish some of this, but most of the time its an "aw crap" moment after the main render cooked all night, and using the clown pass to create a mask is infinitely easier than drawing paths and making selections in PS.

Offline INNEO_MWo

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Re: Render clown pass only?
« Reply #1 on: August 15, 2017, 10:58:27 am »
If I need this I create a new scene set or studio and apply some flat materials on my parts. That simple way of own clown pass can be rendered in performance mode within 1 sec.
I've created some simple flat materials with the Photoshop preset colours of the colour selection tool.

Offline mattjgerard

Re: Render clown pass only?
« Reply #2 on: August 15, 2017, 11:05:54 am »
If I need this I create a new scene set or studio and apply some flat materials on my parts. That simple way of own clown pass can be rendered in performance mode within 1 sec.
I've created some simple flat materials with the Photoshop preset colours of the colour selection tool.

Great idea, then the main RGB image is the clown pass, right? That would work great, as there is less stuff/layers/files to manage.

Offline Speedster

Re: Render clown pass only?
« Reply #3 on: August 15, 2017, 03:30:40 pm »
I often make my own clowns.  If you have a lot of materials applied to a model, KeyShot will often create an auto-clown that is very close in colors, making it hard to select at anything above 1%.  So I pull a KS auto-clown, but also copy (or instance) the model and create my own clowns.  I often do this on "large lumps" or models that I know I will have to apply curves or levels to the entire model in post.  That way I can easily isolate the entire model or models.
Bill G

Offline INNEO_MWo

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Re: Render clown pass only?
« Reply #4 on: August 15, 2017, 09:57:40 pm »
When do you need clown passes in scenes with thousands of parts in hundreds of different materials? Most time I isolate up to 10 different areas and that's all. All I want is to reduce my post time drawing masks and alphas.

I guess the question is how to apply the clown materials to many parts as smart/quick as possible.

Offline mattjgerard

Re: Render clown pass only?
« Reply #5 on: August 16, 2017, 06:47:28 am »
Great thoughts, and I will be using this technique in my next build.

I'm pretty particular about being very organized with my models when building my scenes. I am now assembling and modeling all my stuff in Cinema4D which supports grouping and layering, so I can be very very tight about grouping different parts of my models and scenes. The awesome C4D plugin for keyshot does a great sjob in honoring the heirarchy, so I could use those groups to apply flat materials to whole groups of objects.

This last one was I had an aseptic isolator with a bunch of bottle filling cruft inside that I needed to tweak, but it was all looking through windows, so the window provided a single flat color in the clown pass. i had to turn off the window so the clown pass could see through it and give me different colors for all the objects inside the unit. This is all fine, its the way it should work, and knowing that I can group all the stuff inside the machine into one group and apply a single flat color and shoot out a quick RGB clown would have made my life a slight bit easier yesterday.

Anyhoo, thanks for the tips,  I might put in a request to see if the clown pass can have a checkbox that would allow it to honor transparency. Basically if the object is more than X% transparent, ignore that material and apply the clown colors to the objects behind the transparent material. That would be cool, and since I'm not a programmer that gives me license to say that it would be totally easy and complain as to why it hasn't been done yet :):):)

Offline INNEO_MWo

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Re: Render clown pass only?
« Reply #6 on: August 16, 2017, 06:53:04 am »
this topic about transparency is already discussed inside this forum. It isn't as easy as it seems.

Attached you'll find my clown pass materials described in German.