I’ve had these problems before in the standard scanline renderer, but I was wondering if vray had anything available to solve the issue.
Check the attachments below. I have a vrayBlendMaterial, the base material is just a grey diffuse, and the Coat material is referencing a bitmap for its color (the color channel of the bitmap) and opacity (the alpha of the bitmap). The bitmap is saved as a transparent tif through photoshop. The rendered result has nasty dark rings around it, ie, it’s not compositing properly. Un-pre-multiplying the texture helps a bit but not much. Using the alpha as a mask in the vrayBlendMaterial instead of an opacity has the same results.
Does anyone know what can be done to solve this? Some sort of extra operation on the bitmap? A different bitmap format?
Any advice will be uber appreciated.
- Neil
PS: I’ve included the max file (2014) if anyone wants to play with it.
Nope, as I mentioned, using the alpha as a mask in the vrayblend material instead of in the opacity causes the same problem (I should have referred to the “mask” as the “blend mask”, my apologies for not being clear).
Make the top coats diffuse color the same mid grey.
Because of the alpha map, 3dsmax samples the diffuse color in the actual color slot (which was black)
Well, that solves this simple test case, but the real material I’m using contains bitmaps in 5 different base layers/topcoats, not a simple grey color, so afraid that technique is a no go.
But thanks for giving it a try! And thanks for the compliment, glad you’ve enjoyed my work.
I had a hard time getting this to work - you could run it through a composite node but obviously you lose the modular approach. Or paint wider than your Alpha but that’s a pretty gash solution.
I’d be interested to hear if there’s a better way.
saving tes2.tif as a png seems to fix your issues ? (as most apparent by the yellowish spots)
I assume it’s an issue with the Tiff file format.
(the only application I know of which handles this right is After FX where you can say what background the input image is premultiplied against.
saving the transparant image as a png seems to come in right in max as having no background
(though the way max displays the images (view image) looks rather weird)
Yves is right, Max seems to always multiply transparent TIFFs against black. We don’t have 2014 installed here yet but if you do view image on the Tiff inside Max it will probably show it with a black BG.
Awesome, thanks you guys! Last time I tried this (like 7 years ago), tif was the format that worked the best for me. But png works great now (I’m pretty sure I tried png last time and it didn’t work, but who knows).
I had this exact issue on my last job. I can tell you exactly nothing because I couldn’t solve it
Essentially the alpha/mask is not multiplying against the coat shader? I’ll do a test later today, as I probably
will be using blends with coat masks in the future.
In Gimp there is a option for saving color-values for transparent pixels. With that option on the blending is perfect
Don’t know which software are you using for your tiff files - but try to find out something similar.
