Blender bake transparency

Hello. I have some problems in blender to bake transparency. It works fine in 2.79 but its not really working in 2.93, i think i got it to work before but then i forgot how i did it. I have tried all settings i can find that has something to do with transparency but it just wont work.

Here is a youtube video that shows my problem

Hi there!
If the pnd is aplha cut, you shall not need an opacity map, plugging it into the alpha, with aplha blend mode should simply work.
If you really need to bake opacity from an apha cut png image, in theory, the greater than (0.00) should mark all areas, that are not alpha cut, then you could bake it out as a simple photo, from the colour or emmission, etc… plug it in and bake it, that should be it I guess:

I tried using Math Greater Than but its still not baking it with transparency

Can you attach or link this png that is in question? :slight_smile:

I have tried with several different images. It doesnt work with any image really

First, you add the image, make sure the Import Images As Plains addon is enabled, then you can Add Image, Images as Planes. Then Blender will auto UV unwrap your picture.

In the Material Properties (red gray ball, right menu) and in there Viewport Display should be Alpha Blend for Blend Mode, then the alpha into alpha should work as opacity without any opacity maps.

If you want to actually bake the opacity map (black transparent, white is seen) then you can add a Greater Then Math node for the colour of the image. As you can see, the alpha cut is not soo smooth, contains artefacts, and it might be an issue, if you want a clean image, but you would need to correct the alpha cutting in an external editor, e.g. GIMP. Mostly it should not be seen in a large composition.

Now that we have it, you make sure the UV map is selected to render, but it should be by basis (right menu, green triangle (object data properties) there UV, it should be selected with the white (active) camera icon.

Then click the object, in the other window create an image texture with the resolution you want (rectangle aspect).

Then you connect the node you want to bake into the shader output, and make sure your image texture is selected as well.

Then go Baking, select Emit, and click bake. The render settings are applied for baking as well, so in this case you only need a few samples like 8-16 maybe, I think it shall be all fine.

Once baking is done, you can go to image editor, and save the image you baked :slight_smile:

Also, I advise you to watch some nice youtube tutorials on baking textures in general, e.g. this one:

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I cannot use the images as planes addon because this is not the image im trying to bake. I am trying to bake something that is not a plane. I just used this image because its more easy to just bake a plane. Anyway. And yeah, i have used blender since 2010 so i have a pretty good experience with the program. But i tried selecting emit from the menu but it still doesnt bake with transparent background. If i select emit i dont get any colors its just all black in the baked image. if i select “Combined” or “Diffuse” i get the image i want but with black background behind my UV and outside my UV it is transparent. But everything under my UV has a black background. but if i select Emit then everything under my UV is just black and i dont even get the image i want in the center of the UV. And yes my Alpha Blend Mode is “Alpha Blend”

Well, the baking bethod depends on what the object is, and what you want?
Only to save the shader maps as pictures, or you want to bake a high poly texture to a low poly mesh? It all depends on the exact plan.

If you like, we can take a look at your exact model and how you like it. I may be able to assist, maybe others will jump in as well :slight_smile:

I just want to save it as an image. I am baking a Wing Model for World of Warcraft and the wing has some holes in the skin so i need to bake transparency. I cannot use the original image for some reason in world of warcraft. I need to bake a new image in blender otherwise the texture dont show up in game…

This is the wing model that i am trying to bake.

If the model is UV unwrapped, and you have the alpha transarency, in Blender it should work fine.
If you want to bake a black and white opacity map, you can do exactly the same that I showed you just with this model. You can use smart UV unwrap, that should do the trick, with a lil island margin like .004 when unwrapping. But the method itself is exactly the same.

Of course you would need to bake all maps with the same UV unwrap to use them together. Colour, Roughness, Bump, etc…

Yeah i dont really need an Alpha Map (Black and White) i just need image with transparency. I am not really sure why its not working because in Blender 2.79 i just need to go in texture settings and select Alpha and make sure the alpha is set to 1.000 then go in Materials Settings and select Transparency and click Z Transparency and change alpha for Z Transparency to 0 and it bakes it with transparent background. But i have not used 2.79 in years so there is a lot of other things i have forgot and i dont really wanna model in 2.93 and then go back to 2.79 to bake the image and i dont really wanna just do all in 2.79 since i have forgot so many things about this version. so i would prefer to just do it all with 2.93 version. but apparently it is not working.

Anyway, thanks for trying to help ! Very much appreciated

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Well, in that case, why not just alphy cut it in GIMP or somewhere? Then you would be sure it is done properly. Okay, might be a bit slow, but you can create a quality asset :slight_smile:

Yeah thats a bit too slow :stuck_out_tongue: I have plans on making a bunch of different wing models and sell so i need to build up a collection of a bunch of different models quickly. Oh well… I guess i have to re-learn 2.79 lol :stuck_out_tongue:

Well I see, but the png itself is alpha cut, you should have no issues. If not, the Greather then may still work.
If not confidential or so, you can share the blend file and we may take a look :slight_smile: don’t forget to pack the textures :slight_smile:

Yeah sure i can share the blend file. Just give me a minute

Hi, the normal PBR workflow would be to make a black and white or greyscale “alpha map” or “opacity map”.

PBR separates diffuse, metalness, roughness, alpha, normals, etc into different images (maps)

As you intend to sell your models I would not put the alpha information in the diffuse image map.

If you search PBR textures online you will find that they include separate opacity maps for the alpha channel when needed.

So i cannot upload because im new user. But i uploaded to Mediafire

SInce the model will be used for World of Warcraft i need to have trasparency in the same image as diffuse. I cannot have a separate alpha image.