Alpha Contribution

[gery_cg]

Hi, i was wondering if there was any way using the alpha contribution to get different masks for different materials. I always put the floor as 0 so i have a mask of the full object, but what happens if the contribution differs from the materials? Is there any way of using that info in Photoshop for creating perfect masks (with antialiasing) for every material?

Thanks!

Gery

[dalomar_cg]

Re: Alpha Contribution

Yes, you definitely could. It would require rendering out a number of passes and setting the alpha contribution for each material/pass. Basically what you want would have a contribution of 1 and everything else would have an alpha contribution of 0. This could be done via scripting but since all you care about is the alpha for the mask (you should already have the original rendered image) then you should adjust your settings so that the render doesn't take as long (ie use saved GI solutions (or none at all), don't use blurry reflections)

[Micha_cg]

Re: Alpha Contribution

Gery, you have seen?

http://asgvis.com/smf/index.php?topic=5039.0

It should be faster than manualy change materials and setups - select you objects you need a mask for and press the mask render button.

[gery_cg]

Re: Alpha Contribution

dalomar, that's usually what I do, before the alpha contribution thing I only rendered the parts I needed to masks unchecking some boxes in the preferences, now I do it with the alpha contribution, although I thought there was probable a more "pro" way of doing it. Maybe in the future =)

micha, yes, I saw it and I was going to try it when I have the time. Unfortunatelly my DVD drive broke when I uninstalled Windows partition out of my mac and was going to reinstall. Now I have no render engine until I buy new DVD... Do you know if there is any work of Vray for Rhino Mac? I know it isn't even finished, but maybe someone is already working with them.

BTW, the .exr file, how do you open it? When using the OpenEXR plugin in Photoshop i get only one layer. With ProEXR plugin I get all of them and seems to work fine, but maybe there is a workaround with the plugin already in PS (is that the command line thing you told me dalomar?). Will it be updated in CS4?

Thanks guys

Gery

[dalomar_cg]

Re: Alpha Contribution

I thought there was probable a more "pro" way of doing it. Maybe in the future =)

I'm not sure exactly what is the way most "pros" do it. I know there is a little v-ray plugin called VRaySphereFade, which basically allows you to put a little gizmo around an object to only render whats in that sphere, and it kind feathers out for smooth compositing. I'm not sure if thats the best way, or the most effective, but it might help out.

There are a few channels that will be available soon that might help out. Those will allow for some selection of specific object based on their uniqueness or their material (I can't remember which at the moment).

[Micha_cg]

Re: Alpha Contribution

There are a few channels that will be available soon that might help out. Those will allow for some selection of specific object based on their uniqueness or their material (I can't remember which at the moment).

Antialiased? Wire color channel?

[dalomar_cg]

Re: Alpha Contribution

I've explained why the MatID channel isn't antialiased and we are consistent with vfMax on this. Unless Vlado changes this behavior (which is highly unlikely), then it will stay as it is.

I'm not sure what the situation regarding wire color is.