Zbrush: Some fairly minimal normal map issues

mrlemonyfresh

Hello everyone

I'd like to show you these:

(See attached, i can't seem to get the included img code to work)

I circled problem areas.

From left to right:

-What's that, how did it get there..?

-Can I get the contours of the lines to bias more towards the hi rest mesh instead of so straightly along the lines of the low mesh?

-Again, what is that? looks like the normal folded in on itself or something.

Please let me know if you need any more information.

Eric Chadwick

What's your workflow? These look like errors you get from changing the lowpoly mesh after baking. Did you export your highpoly out of Zbrush and bake in Maya, or somewhere else like Xnormal? Did you make any changes to your lowpoly after baking the map? Any overlaps in your lowpoly UVs? Any UV mirroring?

mrlemonyfresh

Hello Eric, and thankyou for taking the time to help.

Well, I baked the high poly onto the low poly within zbrush and the low poly one had been altered by the higher poly versions (as per usual). I did not change the low poly one after baking, this is normal map straight from zbrush back into my original low poly model. All the verts are still there and nothing is taken or changed in the topology, it's just a slightly different shape.

Long story short, my workflow in this case goes:

Maya: low poly model and uv export to obj

Zbrush: subdivide, reshape, create normal map

Back to maya: apply normal map to original low poly model.


You can see the errors in the actually normal map. I'll find them now and upload them really soon.

I'll show you the normal map and point out to you where the problems are.

mrlemonyfresh

Ok I already diagnosed the problem with the cheek bone, it's simply an overlooked UV problem. Some how i managed to merge some uvs in the cheek bone.

(see attached: 1 )

The problem i guess will be replaced the uvs of the one in zbrush.. but how..?? or do i need to start again?

But as for the other problems, i still don't know the answer to them.

However, have a look at the normal map screen shot (attached 2) as you can see, there are some places mainly along the edge of islands/UV_shells where there appears to be a seam which has come apart for some reason.

Finally, I still need a way of getting a more rounded normal map that defies the sharp and angular directions of my topology, is that possible?

Eric Chadwick

I would suggest not baking in Zbrush. Xnormal or Maya will do a better job with an exported model.

I haven't baked normalmaps in Zbrush, but it looks like the gaps are places where the raycasting failed, where the baker couldn't "see" the highpoly surface for some reason. Could be overlaps, could be ray distance, dunno.

Getting a better rounded normal map... that means you need a better lowpoly mesh. Have you seen these threads?

You're making me hard. Making sense of hard edges, uvs, normal maps and vertex counts

Understanding averaged normals and ray projection/Who put waviness in my normal map?

mrlemonyfresh

That does sound right, duly noted. I'll probably try in xnormal.

Thanks for the direction Eric, I'll have a look at these links when i get back from work.

Eric Chadwick

Xnormal is definitely worth the examination. Highly recommended!

mrlemonyfresh

Just thought I'd let you know that I managed to get a near perfect bake in Xnormal, thanks to the ray casting calculation tool! Unfortunately I wasn't able to get a circle line alone some faces like I wanted but that isn't so bad, and if it's very noticeable near the end I could probably just edit it in photoshop.

One other problem i still have is that I must now replace the base object in zbrush of my character. Recall me saying that I'd muffed the cheek bone UV's before exporting? well i need to fix that now. Hopefully I can replace the base mesh in zbrush.

Eric Chadwick

Check this thread. Importing UV's into sculpted mesh in ZBrush.

(Was the top Google hit for "zbrush uv import base")