Alpha from the Image Tiles node Tweet

[SiliconAya]

Is there a way to get the alpha channel from the 'Image Tiles' node? I've been making use of the 'Image Tiles' node to make a UDIM compatible single material for all skin surfaces for Genesis 3/8/8.1 models, however I've been defeated by a simple png image with transparency, which is how Daz G8F characters do make up (also any product the does overlays/LIE using PNGs, for things like burns, scars, make up, tattoos, body paint, etc).

All the Channel Picker/Merger/etc nodes only deal with the RGB channels, not the alpha channel and unless I'm missing something, the only way to deal with alpha channels seems to be the 'RGBA Image' node, which seems a bit of an oversight?
In other programs and renderers I've used like Nuke and Renderman, channel manipulation type nodes deal with the Alpha channel like the RGB channels, it's just another option in the selector drop down menus, it seems odd that Octane has so little way to deal with Alpha channels.

[birdovous]

Not sure with the recent version of DAZ plug in and Octane, but in the version I'm still using (v4.04 of Octane and corresponding DAZ Plugin) the RGBA image nodes are the only way to deal with such texture files (PNGs with Alpha).

And at least in the old version I'm using I noticed bugs when it comes to combining the alpha channel involving materials. However, that is something I have to simply live with as the versions that I'm using are out of support for a long time...

[toby_a]

Hi. I don't think the plugin is limiting what you can do here, by which I mean I think you have the same capabilities as Octane Standalone. I suggest you ask in one of the more general forums to see if anyone has any suggestions.

The only suggestion I can think of is to combine several Alpha texture nodes (which the plugin calls RGBA for some reason), each with a UV offset in its transformation and Border Mode set to Black Color, together using a Composite Texture or similar. I haven't tried this, just an idea.

Cheers,
Toby.

[huakiami]

I can confirm that the method Toby outlines does work, as that is the method I've personally been using to add layered/masked effects to skin.

I have also converted my skin shader to use ImageTiles nodes for all the primary textures. And while I am in agreement that the options for working with a texture's alpha channel are strangely limited in Octane, I don't think I'd use an ImageTiles node for that even if it did support alpha. I find since I'm often combining multiple masks for each UV (i.e. multiple makeup masks on face, multiple tattoos on arms, multiple wounds/scars on torso, etc) that I'd prefer to just work with individual RGBA nodes rather than a bunch of ImageTiles nodes with mostly blank spaces.

As Toby mentioned, Border mode set to Black Color plus an X Translation works well to get them into the proper UV space.

[SiliconAya]

Thanks for the tips guys, will give them a go.

[SiliconAya]

Also, I'm all for renaming the 'RGBA Image' node to 'Alpha Image' to match Octane standalone, I also use the Maya Octane plugin and it has it's own names for common nodes as well, eg 'RGB Image' is 'Image Texture' and 'Greyscale Image' is 'Float Texture' it can get very confusing when trying to match results and materials between them.

However, the problem of having to convert old scenes using the old node names might make it not worth the effort.

[toby_a]

Changing the names of the node types is pretty easy and has no impact on loading old scenes, so I might just change them all to match Standalone.

[toby_a]

Changing the names of the node types is pretty easy and has no impact on loading old scenes, so I might just change them all to match Standalone.

This was done in this release: viewtopic.php?f=44&t=80596.