Material ID channel process tutorial

[andybot_cg]

Hi All, I wanted to share a process I've been using with the current 1.49.01 version of VfSU. This is a way to use the material ID to mask out a selected material and then composite in a texture in place.

I am using the method similar to Nomer's post http://forum.asgvis.com/index.php?topic=4156.0 but using the material ID channel in place of the diffuse map.

This is also an update for the environment map grass method from Micha http://forum.asgvis.com/index.php?topic=2320.0 since that method doesn't work in the current version of VfSU (the most recent complaint here: http://forum.asgvis.com/index.php?topic=10354.0)

Here is a link to my tutorial:
http://charlottesvillearchitecturalrendering.com/?p=127

[sebekf]

Re: Material ID channel process tutorial

as usual, thx for sharing exhaustive information .

[thomthom]

Re: Material ID channel process tutorial

Nice tutorial.

Though - I don't think using the magic wand to select the MaterialID areas is the best tool. Because you end up losing some pixel information.


When I use MaterialID I either use Black and White colours - so that I get a clean mask. This can be pasted directly into the Alpha channel in Photoshop when you have created a Layer mask.

Another method when I have multiple areas is that I use Red, Green and Blue colours - pure 100% colours. That way each of the colours acts as a layer mask - you just go into the color channels in Photoshop and extract the relevant colour.

[andybot_cg]

Re: Material ID channel process tutorial

@jarynzlesa: you're welcome, hope you find it useful

@Thomas: Thanks! Good point about using white for material ID for a single texture and using the RGB channels for multiple. I imagine that can come in handy especially for issues like seeing the material through transparency.
Since I usually end up painting over the edge of the mask to blend things better (such as at the edge of the bushes) I don't usually worry about the tiny discrepancy. The original image is at 2400px wide, so it doesn't show up in print.

[dkendig]

Re: Material ID channel process tutorial

Honestly the method Micha used for grass never made any sense to me in the first place. Material ID or a matte material (which we don't support yet) would be the way I would go about this. I mean really the important thing is capturing the shadows on the surface where the image of the grass is going to be, and having an area that you can use as a mask to put some grass in post process, right? I don't know, maybe I like post processing more than others. I don't like texture colorization in SketchUp either, so maybe it's just me.

[andybot_cg]

Re: Material ID channel process tutorial

Hi Devin,

Good point. I think the biggest limitation in Micha's grass method is that there is no flexibility in postprocess, the texture is baked into the render. There is much more freedom to adjust the image once you use layers and masks in pp.

Andy

[dkendig]

Re: Material ID channel process tutorial

yeah, I guess some people just don't want to mess with image editing apps like gimp or photoshop unless absolutely necessary.

[nomeradona_cg]

Re: Material ID channel process tutorial

thanks for sharing. i love this simple yet very useful tutorial. btw it was free agent's method. If i remember on some of the question related on the above subject, i just keep on quoting on that particular post which shared to us by free agent. :-[ :-[

[nomeradona_cg]

Re: Material ID channel process tutorial

btw congratulations to your site. i love it. both the NPR and realistic approach were properly documented. How i wish we could have a common site to introduced all these excellent sites. of all fantastic users and visualizers. I hope in few days time i can make one dedicated to showcasing all these excellent sites.

[andybot_cg]

Re: Material ID channel process tutorial

Thanks Nomer!!
Thanks for noting freeagents contribution.

Andy

[thomthom]

Re: Material ID channel process tutorial

Honestly the method Micha used for grass never made any sense to me in the first place. Material ID or a matte material (which we don't support yet) would be the way I would go about this. I mean really the important thing is capturing the shadows on the surface where the image of the grass is going to be, and having an area that you can use as a mask to put some grass in post process, right? I don't know, maybe I like post processing more than others. I don't like texture colorization in SketchUp either, so maybe it's just me.

Micha's process had the benefit that you got shadows imposed on top of the material. When you use material ID to mask out you have to do extra work to preserve shadow areas.

[dkendig]

Re: Material ID channel process tutorial

Yeah, there's another V-Ray plugin that's supposed to be used for that. We will have to look in to adding that to our product.

[thomthom]

Re: Material ID channel process tutorial

Yeah, there's another V-Ray plugin that's supposed to be used for that. We will have to look in to adding that to our product.

yay!
Shadow catcher material?

[dkendig]

Re: Material ID channel process tutorial

essentially, yeah. When we start adding features on purpose, we'll throw that one in to the mix.

[andybot_cg]

Re: Material ID channel process tutorial

Heck yeah, sounds good. More features! (and I'm very much looking forward to the next beta to play with...)

So far I've had good success with material ID and adding back shadows with "multiply" transparency when the material is a light color and low or no color saturation.