Blender to Zbrush for highpoly model - My Struggle

Boosted24v

So I'm fairly new to the 3D modeling world, only been doing it about 5 weeks now. I've been working with Blender 2.8 and was introduced to the concept of using zbrush for smoothing things out and adding finer details on highpoly models. But I'm having an issue. When I leave my model as-is, with ngons on larger flat surfaces and import into zbrush (obj file) the model is ripped apart. I concluded zbrush didn't like the ngons, so I used blender's triangulate faces feature which did infact resolve the exploded model issue but it still made the model look like total crap. Any helpful tips? 

cryrid

You're right about n-gons - zbrush doesn't support them so you'll need to stick to quads and triangles.
Quads will give you the best result when it comes to subdivision smoothing and sculpting. 

Boosted24v

cryrid said:

You're right about n-gons - zbrush doesn't support them so you'll need to stick to quads and triangles.
Quads will give you the best result when it comes to subdivision smoothing and sculpting. 

@cryrid

I've discovered this the hard way lol, I generally try to stick with them (quads). Unfortunately, at least in my many hours of researching the topic, haven't been a whole lot of "best practices" material out there for dealing with this problem. Most will teach you how to make the shapes you want, but won't teach you how to set it up for export to other programs. The main issue being topology from boolean operations. So I'll post a picture of my model with all ngons intact, and one after the automatic "triangulate faces" feature is used. I'm a bit of a perfectionist so I'm just looking for a better way and for a better result. Any tips are greatly appreciated.

I feel like there must be a way to deal with at least some of this with sacrificing the shape I'm trying to achieve. The triangulation really messes with the shape.

oglu

Why do you think this gun has to go to Zbrush?
Just do it the right way and do some hardsurface modeling.

Boosted24v

oglu said:

Why do you think this gun has to go to Zbrush?
Just do it the right way and do some hardsurface modeling.

There were some finer details I thought might be easier to achieve in zbrush, like adding slits in the buttons for grip, grip texture on the pistol grip as well.

Example:

Blaizer

You don't need Zbrush for that, it's an overkill.

Anyways, your mesh is not suitable for subdivisions (it's just a raw mesh), ngons are not the unique problem here. Mudbox can use ngons, and the result would be the same as in blender if you apply a subdivision modifier.

Try to model the dents of that piece you marked. You can achieve easily that look with subdivision modelling. And for the grip details use traditional texture work, It's just a noise texture pattern.

dlz

Boosted24v Can you attach some images of the problem you're having? i always try to get my model with quad faces and some minimal triangles before importing to zbrush. With triangulated faces should work fine too, you can dynamesh or use zremesher or other techniques once in zbrush.

Also i try to use other file formats as .ma or .fbx as i'm having less problems with that files

Boosted24v

Did a quick pass with the knife tool to cut in the grooves on the buttons, I guess it doesn't look terrible lol. Probably a detail most wouldn't even notice, But i'd like it overall looking as realistic as possible.

Boosted24v

@dlz Its just when I select all ngons and use blender's automatic triangulate faces (pictured in above post) it ends up looking like this inside zbrush. I haven't tried doing anything with it inside zbrush yet cuz i've been trying to figure this out.

dlz

@Boosted24v

oh, it's not that bad, you can work with that and get good results.

You can use that workflow(or something similar) and i think you will have a decent mesh:

https://polycount.com/discussion/168610/3ds-max-zbrush-proboolean-dynamesh-hardsurface-workflow-tutorial/p1

i tested with maya and have good results and with blender i think it should be the same

FrankPolygon

@Boosted24v There's a lot of factors at play here but the majority of the issues with the model are related to inaccurate or incomplete shape geometry and noncontinuous / non-coplanar topology. When it comes to the actual modeling process the issue is more of what's being hidden by the n-gons rather than the n-gons themselves.

Both Christoph and Alberto are correct: this object can be replicated in a subdivision modeling workflow. Using ZBrush to re-mesh, smooth and sculpt details on hard surface models is an established workflow but it still requires an understanding of the fundamentals behind low poly modeling and subdivision modeling so it's worth looking at how to resolve common issues with subdivision models.

Here's some sample geometry with different topology layouts. As long as the shapes are reasonably accurate and the individual surface segments are coplanar (flat) it doesn't really matter if the base geometry is quads, triangles or n-gons. The key here is to keep all of the geometry on the same plane as the rest of the surface segment.

The very last sample has a surface segment that is non coplanar. Though this surface appears flat as an n-gon triangulating the geometry reveals that it's not completely flat relative to itself. Since the geometry isn't flat the shape of the surface will change depending on how it's triangulated. To resolve this issue the elements of this surface segment need to be made coplanar.

Here's a closer look at what's happening: the edges along the back and bottom of the surface are both perpendicular and coplanar. The edges at the top and front of the shape are tapered inwards since they are connected to the vertex in the middle of the V shaped groove at the front of the rail block.

The flat shading on the n-gon hides how the triangulated geometry will behave. Triangulating this n-gon generates a faceted mesh where the triangles are out of plane with each other. This means part of the surface will be flat and part will be angled. To resolve this the surface needs to be made coplanar with continuous supporting geometry. This can be done by extending the v shape along the lower edge and creating a transition shape at the end of the groove. Similar to the second to last sample in the previous example.

Here's a couple of the previous sample meshes with various topology layouts and subdivision applied. The first two examples lack support geometry and this causes the shapes to colapse. Adding support geometry to the quad grid and the n-gon topology produces almost identical results. Accurate shape geometry and coplanar surface segments ensures that subdivision and triangulation produces the expected smoothing results. This is where the traditional modeling fundamentals still apply to the Boolean to ZBrush workflow.

Cryrid is also correct: ZBrush only supports triangles and quads but not n-gons. Coplanar n-gon segments can be triangulated without causing major issues and the re-meshing tools in ZBrush can rebuild this mesh in all quad topology.

Here's an example of a triangulated n-gon and Boolean mesh before and after re-meshing in ZBrush. As long as the starting shape is accurate, the mesh triangulation isn't a major factor since ZBrush will do all of the heavy lifting. No need to go overboard with manual cleanup or manually creating quad grid meshes. Let the software do the work.

Here's a comparison of subdivision modeling and Boolean to ZBrush. Subdivision modeling took 45 minutes and Boolean to ZBrush took 20 minutes. The results are largely indistinguishable so it comes down to time efficiency. That said there's still a lot of work that can be done with similar efficiency levels using subdivision modeling and there can be edge cases where having to run something through the ZBrush pipeline for multiple changes late in production can wipe out any time savings.

A good base mesh should be usable as a low poly mesh otherwise a lot of time needs to be spent either re-creating a clean low poly or optimizing an overly dense base mesh. This is where being overly sloppy or lazy with a Boolean to ZBrush base mesh can end up resulting in the time savings being a wash between the two workflows. That's why it's still important to build fundamental modeling skills.

At the end of the day what workflow is right for the project depends on the artist's goals, tools available, and restrictions like time, budget, quality level, etc. It doesn't have to be an all or nothing proposition: subdivision modeling, Boolean to ZBrush, Fusion 360 to MoI3D, etc are all legitimate workflows and it's up to the artist to decide what makes sense for each stage of the project.

To recap:

• Create continuous geometry elements that support the entire shape.
• Create accurate geometry that maintains a consistent surface.
  
• Keep individual surface segments coplanar.
• Use automated re-meshing tools to cleanup messy geometry.

Adjacent issues with exporting from Blender and importing to ZBrush are covered in the guide listed in the resources linked below.

Here's supporting documentation from Pixologic:

http://docs.pixologic.com/user-guide/3d-modeling/modeling-basics/creating-meshes/zmodeler/targets/polygon-targets/

http://docs.pixologic.com/user-guide/3d-modeling/topology/zremesher/

Here's a short guide on exporting Boolean meshes from Blender to ZBrush by Victor Kam:

https://www.artstation.com/artwork/GXWBoQ

Additional Boolean to ZBrush resources:

https://polycount.com/discussion/168610/3ds-max-zbrush-proboolean-dynamesh-hardsurface-workflow-tutorial/p1

https://80.lv/articles/001agt-002mrs-004adk-how-to-build-a-realistic-gun-for-video-games/

Here's a process breakdown that uses both subdivision modeling an Boolean to Zbrush workflows.

https://www.artstation.com/artwork/KaJPER

Here's a process breakdown that uses Fusion 360 and MoI3D:

https://www.artstation.com/artwork/xzKWRY

Boosted24v

@dlz That is actually identical or damn close to what I was going for in terms of work flow, I watched a tutorial on flippednormals on making a pistol. He went from 3ds max to zbrush but I tried to follow using blender to zbrush workflow. But since I'm very knew to this a bit of a perfectionist I haven't established that feel for "good enough" I only know junk and perfect so its a struggle lol.

@FrankPolygon This is probably the most comprehensive explanation of topology that doesn't involve a human face or body. Very much appreciated. So far i've only really figured out boolean modeling, I've only ever tried using a subsurf modifier after I already had something pretty built and in most cases Blender doesn't like me for it an crashes so I'd love to learn more about that flow. Boolean modeling for a new guy like myself kinda like giving a machine gun to a novice shooter, My topology is all over the place but trying to square it away. I'll take a look at the links you posted and see what I can learn, fix and create with it.

dlz

FrankPolygon Incredible explanation! Thank you! And excelent resources linked.

I liked a lot especially the one that uses both subdivision modeling an Boolean to Zbrush.

When testing that in maya and zbrush I figured out something similar some time ago but he has the process very depurated

@Boosted24v If you want to learn more about subdivision modeling you can get easily info in the internet, there's even a thread here in this forum that help me a lot: only trying to do some of the shapes the people post there and see how other people solved, increases greatly your skills in modeling.

https://polycount.com/discussion/56014/how-the-f-do-i-model-this-reply-for-help-with-specific-shapes-post-attempt-before-asking#latest

Boosted24v

@dlz I greatly appreciate all the help and support, It has definitely helped and will continue to help as I try other models as well. I chose this sidearm because I thought it was fairly simple but its definitely proven to be far more complex than I thought it be and really been pushing me. At least from a newbie stand point. I can't wait to get great finalized result so I can try something new and continue to challenge myself and improve. (this is my 4th go at this model, refused to move on until its at a satisfactory level of detail and quality)   

Because of you guy's help I've finally got it into zbrush, as an .fbx none-the-less which google searches had me thinking would never work. Only one out of 16 pieces didn't work (extractor on the slide) so I gotta figure out what the deal is with that part. Other than that I played around with it for a little bit in zbrush using the smoothing brush on the main body (lower portion) I was pretty satisfied, other than the area around the magazine release button. This portion will prove to be quite difficult I think because the lower portion of the gun is molded plastic and the upper portion is steel. This is my first time really using zbrush so I guess Ill be playing around with this and discovering the best techniques to accomplish the look and detail I want. Thanks again for everyone's help

Coolpaulman45

Hey, I am also new to 3d modelling and was running into the same issue as you in when importing from Blender into Zbrush.  You probably already know about this but I just wanted to make sure.  Blender has a version of GoZ called GoB.  Its completely free.  Import with a single button from Blender and then Zremesh.  I might be speaking out of school, but it seems to solve all the topology issues you might run into. 

GoB:https://github.com/JoseConseco/GoB 

How to use/install: https://www.youtube.com/watch?v=2-pFspCbykk

Hope this helps!

gnoop

I have never had to do  subdivision modelling .   it's just extra headache imo.

For Zbrush  I usually just apply triangulate modifier with "keep normals" checked in  and export fbx.

Then import fbx in Zbrush  and do  DynaMesh.   Works fine usually.  Flat things stays flat.

Then export dynameshed fbx back to Blender and project UV on it  from initial mesh. Using "projected face interpolated" typically .    Takes a while sometimes  if dynameshed object is too heavy so let it some time.

Then import back the dynameshed thing  into Zbrush with UVs for alpha displacing   etc  and continue there.

ps, I bet  that GOZ for Blender uses fbx too