Hello, I have an issue with parenting with automatic weights. It says Bone Heat Weighting failed, and none of the bones are weighted properly. I’ve looked around everywhere and can’t figure out how to fix this issue. I tried with envelope weights, which somewhat works but it leaves some of the topology unweighted.
Can anyone please help? Thanks.
Can you put a blend in? Usually it is because automatic weights will not see vertices behind other vertices in a mesh. So you can clean up the mesh or try other strategies like scaling it super big, parenting it and then scaling it back.
You can put a blend in here and give me the URL and I’ll look at it.
Okay, I tried some clean ups, removed some double vertices and such. It didn’t fix it. I’m still new so I don’t know what else to clean up.
Here’s the file, I had to remove some stuff because it’s a fairly big file, but still too big for pasteall.
https://mega.nz/file/is5nEY6B#RuF3mGh9fGc1KwjP553AyCJGfbYudzntW7s-mdvvAuo
It might be due to the high poly count, you have over a million faces. When I get this problem with parenting with automatic weights I add a Decimate modifier to the model and move the ratio slider down so that it drops the face count down to a lesser amount. Then I try parenting again and it usually works.
It usually doesn’t make much difference to how the model looks dropping the face count as long as you don’t go too low with it.
Could be worth a try.
Most times I duplicate the model first then hide the duplicate, just in case I need the original for some reason.
Well first of all, you have triangles. They don’t work well in Blender for deformation at all. Re import your model with quads instead of tris if you imported . As mentioned earlier your mesh is so dense automatic weight will never work on this. The distance between vertices can not be evaluated for weight painting, it is too small. Even if it did work, you wouldn’t be able to move it in the view screen worth a crap, it is way too dense. You need to get somewhere in the low ten thousands. If it were mine I would Retopo it to a lower mesh and then it should work. However if you are adventurous and still want to use autoweights, scale your model and armature up like 100. Parent it with auto weights. Then scale it back down. I got that to work after I applied your transforms on both the mesh and the armature. You can then pose it but it will not animate well.
With the collapse modifier setting? I tried this, brought it down to a 0.05 and it still does not want to apply the auto-weights 
What do you mean re-import it? And by retopo, do you mean decimate?
Where did you get your model? It looks like a game model. If you brought it into blender by importing, then do it again with quads. I couldn’t tell from your posts where it came from like a sculpt, import, modeled, etc. Retopo is a term used to describe retopology for a mesh. You create a new mesh with new topology over an existing mesh. You can google it for Blender. Basicially you create a new model.https://www.youtube.com/watch?v=CuQzPDs99yM
To use decimate effectively, you need to start with quads which you don’t have.
Here’s a video I did troubleshooting the Meta rig and final Rig as well as weighting problems: https://youtu.be/uTo0kXE8mJA?t=5515
This is the run down to narrow your bone heat errors:
Oh, I know I’m quite new to Blender, but I painstakingly made it over 10s of hours 
I’ll check it out, thanks
Okay, one quick question, I tried applying all transforms but it makes a lot of things break lol. Do you know how to avoid this? The eyelashes get long, my character teleports and shrinks.
That means you have either parented things to those eyebrows, or that it is the child of something else.
ALT+P is the shortcut to cut parents, and KEEP OFFSETs.
If that didn’t work, select your object, go to OBJECT menu>Apply transform>Apply transforms to deltas.
If you only have 10+ hours in blender and you’re doing all of this…you’re going to strive some more.
Sorry for the late response, I was busy on other projects.
Haha, well, just this specific character has taken me 10s of hours, I have some experience apart from this character… Although, this is the biggest project I’ve ever attempted… I was originally planning on making a low-poly character for my game, but I got overambitious 
So, I tried clearing the eyebrows parents and then applying all transforms and this happens,
I tested it right now and same deal.
Regarding the weight paint issue:
I had this problem recently with a Riggify rig. I solved it by scaling everything up, by a scale of 2.
Auto weights struggle if a mesh is small. If it’s really small - then try a factor of 10.
All of the above helps too (Apply scale, remove doubled, etc…)
I had the same problem, all the solutions featured here didn’t work. I solved the issue by scaling the mesh and the rig by 10, parenting them, and then scaling them back to the original size. I don’t know why, but it fixed the problem
