Artifacts on baked normal maps

JSArts

Hey guys. Basically I faced the issue  with baking normal map in xnormal, so that is what i have on particular model of tree:  . Maybe, maybe I've chosen not the smartest way of making model but I used tutorial and basically made high polly of tree, then made low poly from it using low resolution zremesher. I just started using zbrush like a week ago. Then made uv, uploaded all stuff in xnormal and got those broken polygons. Tried also to do it in zbrush by dividing low poly until I have high enough density to project bump from high poly so I have neede subdevision levels to bake normal in bzrush and....... got the same broken polygons, exactly the same polygons. I dont know what to do. checked low poly in 3ds max, used turn to poly modifier, checked for smoothing groups, for overlaping vertices..... halp :v


 copy the link to pic if it wont upload : https://www.dropbox.com/s/v9rhkev95o3l2qh/gdg.jpg?dl=0

beefaroni

I'm not 100% sure what's going on but where ever there is a seam you need to have a hard edge. If there are no seams then the edges should be soft. It's possible that Zbrush low poly isn't exporting out smoothing information that will bake nicely. 

I don't have any good resources off the top of my head to help with baking normal maps but there should be something in the wiki and I know there are a few threads here in technical talk that should help. I think superfranky made a introduction to normal maps thread or something. 

EarthQuake

beefaroni said:

I'm not 100% sure what's going on but where ever there is a seam you need to have a hard edge. If there are no seams then the edges should be soft. It's possible that Zbrush low poly isn't exporting out smoothing information that will bake nicely. 

This is backwards. Anywhere you have a hard edge, you need a UV seam, but you do not need a hard edge where you have a UV seam. You can add one though and it's often a good idea.

OP: It looks like there is something wrong with the UVs here, not only do the values look messed up the data doesn't really make sense in relation to the nearby areas. What does it look like with a checkered pattern?

JSArts

Hey, thank you for the idea with checker. Dunno why I didnt check it before, its a kinda basic  thing to do though. Appearantly zbrush UVmaster, in which I made uvs, simply picked random polygons in the model and rotates them welding to main piece with wrong edge......... HOOOOWWWWWW. Anyway gonna fix it in 3ds max. Thank you very much again.

JSArts

Wow. Another question though. I realized there are too many wrong welded polygons and its kind of a pain to reweld them all manually. Pelt tool kills existing seams. Is there any better ways to fix them on more automatic way, maybe another tool or program?

musashidan

Can you post an image of your uvs? Did you unwrap  based on polygroups?

JSArts

Yep, did it with them, but  as  I said in my latest comment I got  those random polygons welded to main pieces with wrong sides.  I dunno how it happened. Now I need to find a quick way how to weld them all without doing it manually - will take forever. uvs here https://www.dropbox.com/s/ds31wq0onfofnf5/weragt.png?dl=0

EarthQuake

I'm not sure if Max has a similar function, but if I needed to do this in modo what I would do is:
1. Select all the faces that are wrong
2. Break them off and move them
3. Select all the edges for the holes you just made by moving the faces off
4. Do a move and sew operation, which will bring those pieces back, but aligned to the correct edges

All of that could probably be done in bulk rather than individually as well.