I'm getting these bald spots on the back of my separate scalp mesh. The hair is not combed behind the scalp, it's just not there at all. Weight painting is totally red for both density and length, and I've tried disabling modifiers like frizz and noise, and every other one. Does my model just have bad genes?
UPDATE: The shader was the culprit! The missing hair was simply transparent, but I've switched the short hair to a simple node, and it's all a lot smoother. The complex setup is still on the longer hair.
I've only got basic experience with Blender's grooming system, but here are my would -be checkpoints:
Check the UV map is in good condition, that those bald polygons are properly mapped;
Check normals are facing the right way for the entire surface
Check the hair isn't poking through the other side or lying parallel to the surface, which seems obvious and you probably already did;
Check you are displaying all hair curves on your viewport, that your limits are enough for the amount of curves
I figured out it was the shader I was using, creating too much variation, and those parts were transparent. I put a simple shader on the short parts and it all looks a lot smoother.
Awesome you figured it out! Strange to hear it was the shader but hey good job troubleshooting