Zbrush 2020 Exporting Normal Map after Subtool has been poly grouped and Zremeshed?

Amank679

Hi All,

I'm sculpting detail on my high poly version of my gun model and came across an issue where I cant export normal maps out of Zbrush after Zremeshing.

So far my process has been:

• Import low poly
• Create poly Groups
• Subdivide (with smooth modifier off) 4-5 times
  
• Zremesh
• Subdivide (With smooth modifier off) 1-3 times
  
• Sculpt detail

The reason I'm doing this is to even out the polygons so I can sculpt easier on the model. The downside to this is that subdivisions are required to export normals, but After Zremeshing, I only add two subdivisions as the polycount itself was quite high from the first subdivision before Zremesh.

My model already has UV's but Zbrush doesn't recognize them and tells me to unwrap. When I do the software freezes up and I have to restart it. If I click New from Uv Check, It created UV's entirely different from what I had in Maya with plenty of Overlapping.

I've atached imahes belwo ofmy Maya UVs and then my Zbrush UVs

Please let me know your thoughts.

Thanks In advance!

cryrid

When you zremesh the model, you're completely changing the topology / vertex order which means the original UV set will no longer match the new model. Same deal with dynamesh (which might be faster than what you're currently doing).

For what its worth, I wouldn't recommend baking your normal maps inside zbrush. It has quite a few limitations (such as its reliance on subdivision levels). If you bake with other programs (xnormal, substance painter, maya, etc), you'll be able to use different models for the high res and lowpoly versions. This means that your sculpt in zbrush won't even need UVs or sub-d levels. 

Amank679

cryrid said:

When you zremesh the model, you're completely changing the topology / vertex order which means the original UV set will no longer match the new model. Same deal with dynamesh (which might be faster than what you're currently doing).

For what its worth, I wouldn't recommend baking your normal maps inside zbrush. It has quite a few limitations (such as its reliance on subdivision levels). If you bake with other programs (xnormal, substance painter, maya, etc), you'll be able to use different models for the high res and lowpoly versions. This means that your sculpt in zbrush won't even need UVs or sub-d levels. 

Ok, that makes sense. My low poly doesn't have holding edges as I'm trying to stay below a certain poly count and with the way my topology is set up in some areas, I can't get clean edge loops for said holdng edges  without going back and manually adjusting those.

I've tried exporting out the high res model with the sculpted detail to bake into substance painter, but the end result has a bunch of weird creases and shapes coming in with the sculpted detail I want.

If I just subdivide with smooth modifiers off, my sculpted detail comes off really rough most likely because of the way the topology doesn't flow evenly.

Kanni3d

Why are you subdividing your sculpted mesh after the fact? It should just be as simple as exporting your high res mesh/sculpted mesh (all subdivs on it), and then grab your lowpoly (Not sure how you're generating it, is your lowpoly simply just subdiv 1? or do you have a blockout from another 3d package) and export that seperately? 

Amank679

Kanni3d said:

Why are you subdividing your sculpted mesh after the fact? It should just be as simple as exporting your high res mesh/sculpted mesh (all subdivs on it), and then grab your lowpoly (Not sure how you're generating it, is your lowpoly simply just subdiv 1? or do you have a blockout from another 3d package) and export that seperately? 

Sorry, I'm super new to Zbrush, but The way I'm going about it is like this:

1. Import OBJ created from Maya
2. Polygrouping areas that detail would be sculpted onto
3. Subdividing 5-6 times with smooth modifiers off (Because no holding edges are present)
4. Zremeshing those polygroups (Using legacy 2018)
5. Subdivding those poly groups 1-2 times for better definition
6. Sculpting detail

The low poly I bring into Zbrush isn't a blockout, but just the low poly model that I'm trying to even out the topology for better sculpting results.

All I'm trying to do is add details like screws and additional linework that's on the grip, handle and a few other areas of the gun.

The smt subdivisions I'm adding are on the low poly model.

I would add a picture, but for whatever reason I' m not able to attach anything.

But like the above image of the polygrouped gun, you can see how the topology isn't even throughout the model, especially the green area poly group.

Basically, the end result I'm trying to achieve is a subdivided high res gun with evenly spaced quads with sculpted detail with full definition. Once that's done, I would export the normal map and add it on to my model in substance painter.

I'm using Marmoset Toolbag to bake the other maps which I would also import into substance painter. I'm only using painter for texturing.

I hope this clarifies a few things!

cryrid

Dynamesh is a better tool for creating a consistent spread of polygons. You might be better off just painting the screws using substance painter though. 

Amank679

cryrid said:

Dynamesh is a better tool for creating a consistent spread of polygons. You might be better off just painting the screws using substance painter though. 

I did try adding some screws via substance painter sometime ago and it does work, but I come across an issue where the edges of the screw detail are really jagged. Not sure if it's because of my texture resolution, but I have it set to 2048.

I'll try out Dynamesh

Kanni3d

Yeah, just keep your obj from maya as your lowpoly, bring a duplicate into zbrush and dynamesh it pretty densely to sculpt. That should do it  

Amank679

Hey all, I've come across another issue, one I've had before where symmetry doesn't seem to work properly when I sculpt detail.

Like sometimes, if I'm sculpted on the left side of the object with symmetry on, the right side doesn't project show the corresponding detail correctly or at all. 

I haven't adjusted any of the symmetry settings, and only have the X axis enabled. It's been an issue for the longest time and usually happens when I switch to a new subtool.

Deform - Unify fixes my issue, but it changes the position of my subtool from where it original sat to center of the zbrush grid.

Please let me know your thoughts.

Kanni3d

Try duplicating and deleteing the previous subtool. This usually happens to me when I import a new subtool, and I notice that it's far from the intended position, and if i duplicate it, the new cloned subtool is placed correctly

cryrid

Make sure Local Symmetry and Mirror are both turned on as well. Otherwise it will center on the top-most subtool, and strokes will apply in the same direction rather than be mirrored. 

Amank679

Kanni3d said:

Try duplicating and deleteing the previous subtool. This usually happens to me when I import a new subtool, and I notice that it's far from the intended position, and if i duplicate it, the new cloned subtool is placed correctly

Sadly, that didn't work for me. An alternate solution I found was after Deform - Unify, I sculpt my detail then go back and put in the original position and scale coordinates the subtool came with on import. It's slightly tedious because I have to type in numbers, but fixes my issue. Thanks for the suggestion though!

Amank679

cryrid said:

Make sure Local Symmetry and Mirror are both turned on as well. Otherwise it will center on the top-most subtool, and strokes will apply in the same direction rather than be mirrored. 

Sometimes local symmetry would randomly disable itself, but the mirror options is always on by default. I only really adjust the X, Y or Z Axis for symmetry. The solution That found is after Deform - Unify, I sculpt my detail then go back and put in the original position and scale coordinates the subtool came with on import.

cryrid

That is a sign that Local Symmetry is off. 

You could try using the Transform: Set Pivot and Clear Pivot options. The former will temporarily place the Subtool's pivot point on the center of whatever polygons are visible, and will temporarily center the mesh to this pivot. The latter will then restore the original pivot and position of the subtool. 

Amank679

cryrid said:

That is a sign that Local Symmetry is off. 

You could try using the Transform: Set Pivot and Clear Pivot options. The former will temporarily place the Subtool's pivot point on the center of whatever polygons are visible, and will temporarily center the mesh to this pivot. The latter will then restore the original pivot and position of the subtool. 

That sound's a lot simpler, I'll try that out and let you know how it goes.

Thanks!

Amank679

cryrid said:

That is a sign that Local Symmetry is off. 

You could try using the Transform: Set Pivot and Clear Pivot options. The former will temporarily place the Subtool's pivot point on the center of whatever polygons are visible, and will temporarily center the mesh to this pivot. The latter will then restore the original pivot and position of the subtool. 

Tried your method, works well for me. Thanks for sharing that! I'll let you know If I come across any issues with it.