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devin
06-04-2013, 08:32 PM
Is it possible to include dissolve and transparency information when creating matte objects or are you just limited to fully black or white?

I have a static scene with a human body which consists of both solid and partially transparent objects. I have another object, a surgical instrument, that passes into the body. The body is wrecking havoc with the render time so I'm hoping to render it out as a static background layer, render out the animated instrument on its own with an alpha channel, and then apply an alpha matte of the body to the instrument to comp it with the background.

I've tried every combination that I can think of in the object > properties > render tab and in the surface editor > advanced tab and I've also ran an exhaustive search in the forums. No luck. Surely this question has arisen before.

I'd really appreciate any insight or info on how best to achieve this. I can probably set up several masks and layers in After Effects but I'd still like to find a solution out of LW too. Inquiring minds...

Thanks,
Devin

nickdigital
06-05-2013, 10:45 AM
You could try rendering out a version of your body that's grayscale and use that as a luma matte in AE.

devin
06-06-2013, 08:52 AM
Thanks for the reply. I've already set up a series of masks in AE but I'll have to circle around and give this a try as well for future projects and to satisfy my curiousity.

gerardstrada
06-09-2013, 07:02 PM
Thanks for the reply. I've already set up a series of masks in AE but I'll have to circle around and give this a try as well for future projects and to satisfy my curiousity.

You could also use DP Image Filter Node Editor to export a transparent mask of the body object. Just input the Transparency Buffer (from DP Render Buffer node) to the scalar input of a DP Mask Objects/Mask Surfaces node and export it in a scalar DP Global Buffer. Do not forget to enable the buffers in Image Filter node.

More about DP FNE usage and Matte objects/Matte Surfaces passes here (http://lightwiki.com/wiki/Multipass_Rendering_with_Filter_Node_Editors#Mater ial_Matte_Pass).



Gerardo

devin
06-10-2013, 07:42 AM
Thanks, Gerarado. I should have known that DP would have something to address this. I'll give it a shot. Much appreciated.

stiff paper
06-10-2013, 02:40 PM
Is it possible to include dissolve and transparency information when creating matte objects or are you just limited to fully black or white?
The automatic matte objects are limited, yes. However...

Before LW had an automatic way of making any object be a matte object (i.e. back in LW 5), everybody used to make their own.

You start by saving out a copy of your object with the name changed. What we used to do was simply add the word "BLACK" in caps to the original name. Do this first. You don't want to accidentally save over your real object. Then you turn off all of the surface settings. Zero diffuse, specular, reflection, everything. Also make the surface color be black so you can see it's a matte object in the viewports. In the regular surface panels (i.e. not nodes) under the "Advanced" tab there's a setting for "Alpha Channel." Set it to "Constant Value" and 0. Save out your new BLACK object. You've now made a matte object. Whenever you need it you simply replace the real object with its BLACK version.

What this means is that you can now dissolve your matte object. Also, you can make specific surfaces on it be transparent, or you can even texture the transparency on specific surfaces. (If you use transparency you'll need to set the alpha back to "Surface Opacity" again.)

Areyos Alektor
06-10-2013, 06:48 PM
You can use a Transparency Map as Clip Map, just think to set Layer Opacity to a value slightly greater than 50 percent for the Clip Map.