ZBrushCentral

Flipped normals during retopo. Why?!? (URGENT)

ZBrush Usage Questions
#1

Well, I’ve had this problem a couple of times. I start creating my new topology and, somewhen, Zbrush decides to flip the normals of my new topology, so when I project mesh details everything goes to the hell of corrupted meshes (I mean, the mesh explodes).

The last time this happened to me I just changed the Projection Range from 0.1 to a negative value and everything was fixed. After that I simply made the new adaptive skin and with the new tool I flipped the normals before I created normal and displacement maps (if not, when exporting with GoZ to 3dmax normals are inverted and the maps are useless).

But now I just can’t do this because only one part of my new mesh has flipped normals. Even more strange: Zbrush only flipped the normals of the hand I created, the other one (created by symmetry) is fine.

I have no idea why Zbrush inverts the damned normals and why only to one of the hands. I really need to know the reason and a possible solution as soon as possible, please. I need to finish this topology in less than 24 h.

Thanks for any idea.

Flipped normals.jpg
Flipped normals.jpg1214×446 69.5 KB

#2

Hello

Since you are on a time crunch. Why don’t you just work on the hand that is fine and then do a duplicate and mirror to the other side or use the Mirror and Weld option.

keep in mind the Mirror and Weld option can not have subdivision levels so you would have to rebuild them after.

On another note the Projection range being changed to a -1 will also fix this issue.

Let me know if any of these helped you.

Can I also see a wireframe of your new topo?

Paul

#3

Thanks for your quick response, gabo.

I tried giving a negative projection range value but what happens then is that while the “broken” hand gets fixed the other hand and the whole head (the part of the mesh without flipped normals) implode. I guess this keeps happening because the flipped normals are still inverted.

So, how does the Mirror and Weld way goes? I finish the hand, then delete the wrong one and mirror and weld. Will this create a nice left hand? And do I have to do this before I make the new adaptive skin or after that? If it is after, will I be able to rebuild the lower subdivision levels without losing my clean topology?

Some screencaps of the wireframe:

1.jpg

Thanks again, gabo!

Attachments

2.jpg

3.jpg

#4

Hey

Yes you must make it a skin before you Mirror and Weld. You will lose your subdivide levels however if you use Subtool Master Mirror you will not lose your subdiv levels.

Let me know how this works.

Paul

#5

You can also try flipping the normals of the messed up hand inside of zbrush before you project your details. Hide everything except for the polygons that need their normals flipped, then look under tool->display properties-> click flip. After that unhide everything and project details through the subtool menu.

#6

@gabo:

I finally went through. I think the problem was that I started again the mesh from the fingers while the head was yet open. I went on from the neck and did the arm. When I reached the hand nothing happened, the skin projected just perfect. And so the rest of the body.

But I’ll keep in mind the Mirror and Weld, may come in handy in the future. Thanks!

@nstine:

Sounds interesting what you said, but I think I tried to flip normals during retopo and it wasn’t possible. Maybe Zbrush doesn’t allow to flip until the new mesh is finished and turned into Adaptive skin.

Have you ever tried to?

Anyway, thanks for your time.

#7

I believe you would have to flip it after creating an adaptive skin and then append the skin to the original and project details from the subtool pallete. However, you could try going into preview mode and flipping the normals there and see if it carries over into the adaptive skin, but my guess is you will have to do it afterwards.

#8

Flipping the normals in Preview mode is definitely not possible. At least I couldn’t, I don’t know if I did something wrong. But maybe the other option will work.

Is it possible to project details onto a subtool which actually isn’t a Zsphere? I didn’t know it. I’ll try it.

Thanks!

#9

Yes, you can project details onto normal meshes and etc, not just zspheres. All you need are at least 2 subtools. Make sure that both are visible and select the mesh you want to project details onto. Then under the subtool menu press Project All. You may also want to store a morph target before you project so you can use the morph brush to help fix any areas that projected incorrectly.

#10

I knew the process of projecting subtools because I use the appended Zsphere retopology method, but I thought it was only possible to project onto Zsphere based subtools.

Good to know. I’ll try.

Thanks!