Rendering VRay Decals

[JuhaHo]

I wonder what I'm doing wrong this time. I have these client sticker, that I'm supposed to clue to machinery. I'm using *.png files with alpha channel. The opacity is not rendered correctly.

E: The black parts are rendered transparent.

[bardo]

Two questions:
- why don't you post on the 3dsmax subforum? It seems you're a max user...I suppose you'll have more probability to found support.
- have you tried with another decal using the same file format? Are you sure the PNG is totaly transparent where should be transparent? have you tried with another file format like TIFF adding an alpha channel ? Could you show the problematic part of the render and the same part of decal image?

[JuhaHo]

Thanks,

I captured a small portion of the decal. To me it looks like it has alpha channel.

I'm not sure which would be the correct subforum to post these. There are so many.

[bardo]

I'm not sure which would be the correct subforum to post these. There are so many.

In my opinion you could write here. If you post there, I suggest to add also the result of the render (I think it's enough the problematic part if you want to protect the confidentiality of the image)

https://forums.chaos.com/forum/v-ray...s-max-problems

[bardo]

I've set a simple file.
3ds2022 + vray5

[JuhaHo]

Thanks,

I'll test this later. I'm rendering the main image since yesterday. Once it's finished maybe later today, I'll return to the decals and rerender those areas with region render

[bardo]

Watching the manual video about decals, you can see that you can set a file to use as mask.
So, I suggest, while you waiting for the final rendering, to create the mask map to use with the decal.
In this way it should work.

[JuhaHo]

Actually, I'm already using the image as a mask.

[fixeighted]

Why not just invert the map?

In any case, with the settings you showed there should not be an issue, unless you inadvertently had 'invert' ticked already

[JuhaHo]

Thanks,

It's still rendering the original image (started yesterday). When it's finished I can start playing wit this issue. The sticker originally came as EPS, which I converted in Photoshop to PNG with alpha channel. I have encountered this issue earlier, but somehow managed to get the transparency right. However, even if I use the old decal model I need to solve the transparency issue whenever I change decal image.

[Vizioen]

Thanks,

I captured a small portion of the decal. To me it looks like it has alpha channel.

I'm not sure which would be the correct subforum to post these. There are so many.

I'm guessing you're looking at your PNG file in photoshop. What you see is, it the transparency layer of the PNG, that is not the alpha channel. You can see if it has an alpha channel in the Channels window of Photoshop. The alpha channel should be black and white (maybe grey if you have semi transparent parts).

From ChatGPT as I'm too lazy to explain it myself:

• Transparency vs. Alpha Channel:
  • The transparency you see (checkered background) is stored in the PNG file's transparency information, not as a standalone alpha channel.
  • Photoshop renders this transparency directly as part of the image layer, but it doesn't automatically create a separate "Alpha" channel in the Channels panel unless you explicitly add one.
• Photoshop's Transparency Workflow:
  • When you open a PNG with transparency in Photoshop, the transparency is embedded in the layer itself.
  • Instead of showing up as an alpha channel, Photoshop integrates this into the layer's transparency mask (essentially baked into the layer's structure).
  • The transparency is visible but not represented as a separate "Alpha" channel unless you manually generate one.
• Creating an Alpha Channel for Transparency:
  • If you want the transparency to be represented explicitly as an alpha channel, you can create it manually:
    1. Go to the Layers panel.
    2. Right-click the layer and choose Select Pixels to create a selection based on transparency.
    3. Switch to the Channels panel, create a new channel (this will be the alpha channel), and fill the selection with white (for opaque areas) and leave the rest black (for transparent areas).

2 options:

- So either you have an alpha map in your PNG image, then just duplicate that map in 3dsmax (as you don't want to change the logo itself I suppose) and set the Mono Channel Output to Alpha, then use that map in your decal mask
- If you don't have an alpha channel, create a black and white image (white = visible logo, black = transparent) save it as a separate PNG and use that as the decal mask

Bonustip: I've already said this to you in a different thread as well as Bardo in this thread, just post your issues in the 3dsMax forum (issues in this case), you use 3dsMax so that's your DCC, and that's the subforum you need to use.

[JuhaHo]

Thanks,

I don't know. I have spent quite a few hours creating this texture from scratch. I have used Standard Max Bitmap as well as VRay Bitmap. I have tested PNG, TGA and PSD.

E: I made it. I Disabled the Mask option and used only material opacity. So, never use Decal opacity.