Alpha by texture isn't fully transparent

[Micha]

Hi,

I tried to use the alpha from the PNG, but it doesn't work, the alpha is semi transparent only. Did I something wrong?

-Micha

[Micha]

Here I deleted the underlying diffuse layer and I ask me how could I get the area around the non tiled texture transparent?

[natali.velcheva]

Hi,

The way an alpha appears (white/black/glitched) depends on the software used to create the PNG file in the first place. As a workaround, you can try the following steps. The first one is about Opacity map. Slot there your png file and wrap it in a Color correction texture. In the Color Correction, go to Rewire Channels, for RGB channels use Inverse Alpha (01).

After that go to the Bitmap - Color Manipulation and enable "Invert Texture" and "Invert Alpha" (02).

The second thing is to disable the Diffuse Texture Alpha (03),

the png file doesn't have its channels properly set and that is the reason you don't get the expected result.
We know that this is not the best solution but it will save you from modifying the texture in external image-editing software.

Kind regards,
Natali

[Micha]

Thank you for your suggestions. What would be the way to get a clean texture PNG? Would the perfect way be to have a picture with a backround color and to add an alpha map? Which background color works?

[konstantin_chaos]

Hi Micha,

So there is no issue with your PNG or any other for what is worth.
The thing is that many applications (like Photoshop for example) let you work with transparency directly so you don't really see the RBG colors for the transparent pixels.
On save PS will generate the RGB data for the transparent pixels in an automatic way and convert the opacity to an Alpha channel.
If you look at the RGB data afterwards it looks strange (blocky colorful areas surrounded by white pixels) but this doesn't matter since the alpha is preserved in a separate channel.

If you then use the approach suggested by Natali, the rendered result will be correct.
If you want to direct the way the raw RGB data looks, you'll have to basically paint the RGB and add an alpha channel.
Keep in mind that if you just add a BG color in PS against the existing transparency (in your example texture) the final result will not be what you expect - there will be a color bleed right at the alphas edge.

In any case, we'll do our best to improve the workflow you've originally utilized.
We'll also try to improve the workflow for decals creation in Rhino as a whole.

Regards,
Konstantin

[Micha]

Hi konstantin_chaos ,

thank you for the insight. Interesting maybe that I found ways to get it work. First I setup the material at VfR2, since I know, there I get what I need. Later I load the material to VfR4 and I was surprised - it works. So, I finished my project.

Today I tried to find why it works on this way and I found the key option - it works if a transparency map is used and the default color is right set. Per default the color is a medium grey and so the range around the decal is half transparent only.

The opacity by texture alpha can't be used since the default color for the embed alpha can't be set. A simple solution could be if internal it would use black instead the current white. An other solution would be a default alpha color. But also if the default alpha color can bet set, I tried to create a material per VfR2 and I was surprised again - it works too. So, it seems to be an internal setup problem only. Attached the material for this kind of setup.

Additional the viewport of Rhino 5 and VfR2 shows no tiling if tile is disabled at the Vray material. At Rhino 6 and VfR next the texture is still shown tiled. I hope this could be fixed too.

Best -
Micha