Author Topic: Some questions about render passes  (Read 1251 times)

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Offline Andrew_G

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Some questions about render passes
« on: February 15, 2019, 04:29:34 am »
Hi,

I`m super fresh KeyShot user - as for now I use trial version. In my work I use Cinema4D and Vray but as I do pretty similar renderings (to each other) and all of them are basicaly product shots, I though that I may a give try to keyshot. But as always, I have some problems about some issues, and who knows, maybe you can help me out:)

1.
In my work I must use render passes. I need to separate some object elements from another. Is there any way to force KeyShot to use better AntiAliasing for Render Layers? If I render an object  with Include Alpha option it has great antialiasing. But only if I put the same object into Render Layers, the same object has very ugly AA. I tried all three AA options, and unfortunately all looks bad. I know that I can use Defringe option in photoshop, but hello, we have 2019 year:D

2. Can I force KS to render Reflection pass along with specular? Or even render specualr as separately pass? As for now I deal this issue in a simple way: I just make a second render with pure black color and use this second render as Reflection / Specular layer in post process, but making second render is making my work harder:)

3. Can I use render layers for objects behind glass? In vray I could use All Channels option for refraction material, and if I set meterial or object ID for another object in render results I will see separated mask for this object (or material). Can I do this in KS?

Sorry for many question, but these ones are most imporant for me:)

Offline Esben Oxholm

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Re: Some questions about render passes
« Reply #1 on: February 15, 2019, 07:16:55 am »
Hi Andrew.

1. I've had this problem myself. What I usually do is to create my own mask (as you do right now for the spec pass) using the flat material type in black and white variants and render it out using the Custom Control rendering mode as it has nice AA than using max samples.

2. You can render Reflection as a separate pass. Wouldn't that be the same as a specular pass?

3. To the best of my knowledge, the answer for this one is no. Not currently.

Hope it helps a bit. Let me know if something is unclear.

Offline Andrew_G

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Re: Some questions about render passes
« Reply #2 on: February 17, 2019, 03:03:35 am »
Hi Esben,

Thank you for your anwsers. I`ll try to make these special mask that you wrote. As for now I`m not sure how I can achieve it, but I`ll try to dig it in:)

Regarding to reflection pass. I made some testing renders in vray and KS, with same simple object and very similar HDRI as lighting and results for reflection passes was quite different. In general, reflection pass should look the same as normal rendering except color of the object - it should be black with reflection. When you render (for example) black glossy cylinder with reflection pass you should have two almost the same images from "normal" rendering and from reflection pass. But in KS these images are completely different. And reflection pass is just... dont want to say ugly, but it doesnt match the original image.

In KS manual you can read (https://luxion.atlassian.net/wiki/spaces/K8M/pages/315588719/Layers+and+Passes)  that reflection pass is without specular reflection and I think that this might be the reason why it looks like this.

As for now I have a crush on KS, but these two things (reflection pass and masks) make me sad. Instead of one render (just like I have done it in vray) I have to make three renders. Normally it wouldnt be a problem, but usually I need to make few visualisations of some objects a day. And with such a workflow it may be a little hard to achieve.


Offline Esben Oxholm

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Re: Some questions about render passes
« Reply #3 on: February 17, 2019, 11:59:10 pm »
Hi Andrew.
Thanks for clarifying.

My passes game is not my strongest asset :)

I totally see that it adds quite a few extra steps to your workflow when you need it several times a day.
You can streamline it a bit by using multi-materials and studios, but I agree that it's not optimal in your situation.

Hope you are able to solve it one way or another.

Offline PerFotoVDB

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Re: Some questions about render passes
« Reply #4 on: March 25, 2019, 06:45:05 am »
+1 on this question.

Have the same issues here.
Rendering clown passes with transparent objects is impossible :(