Full Version: Auto-retopology algorithms compared

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O.k., did a quick and not so much in-depth test.

The first object looks very good, while the second object has
some issues with the small ribs. I may have to check out
better settings, while i must also admit why to remesh such
objects … , when one could either use the .obj files from MoI
or model them directly with ZModeler …





Regards
Stefan

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Hi Stefan, those are some good results!

> I may have to check out better settings, while i must also admit why to remesh such objects …

Well people ask for an "all quads" output from MoI pretty frequently, and these are the kinds of objects where it's difficult to do that (while also being not unusual CAD models as well) so it's a good example of why MoI does not have that function currently.

- Michael

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How these 2 objects have been transformed into OBJ format ? from what start format ? With what program ?

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Hi Michael,

yes, I understand what you mean. Maybe people requesting such a feature are used to
subd modeling only, prior they discovered NURBS modeling and see a need for this?

But I have never read from them what purpose a quad only CAD model should serve.

Best regards
Stefan

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Hi Pilou,

Michael posted the files in article 8817.23 of this thread. You only need to load
the models into MoI and then export from MoI as .obj, to load into ZBrush.

Regards
Stefan

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I have missed the posts...

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The original files are NURBS models, saved from MoI as
high-res quad/tries .obj meshes and then brought into
ZBrush for ZRemesher.

Regards
Stefan

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O.k., no problem.

Regards
Stefan

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I don't remember if ZBrush accepts the Ngons ?

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Haven't tried yet with 2019, but i remember from the past
it did not like ngons.

For this example i used quad/tris output from MoI.

Regards
Stefan

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Hi Stefan,

> But I have never read from them what purpose a quad only CAD model should serve.

Some people have the idea all quads = always good for everything, not all quads = always bad for everything. That can kind of get drilled in for people who have been very focused on sub-d modeling only for quite a while.

- Michael

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<< For this example i used quad/tris output from MoI.

No more prudent only triangles ?

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There is only that works not! (tell me if you see the images)

I don't know if the problem is from Moi (Nurbs to OBJ) or new ZBrush algorithm...

Inside Moi I take Maximum number of Polygons default, export only triangles and subdivide Larger than 2 unity / All

that was more false then less polygons and no subdivide Larger than


Inside ZBrush it's not me that make the test! (not yet install new zbrush)
Inside ZBrush : Import obj
Polygroups / Normals
Crease / Crease PG borders
KeepGroups & Keep Creases activated
SmoothGroups = 0

a new test must be arrived with a subdivide Larger than 1 unity / All

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Hi Pilou,

very interesting. What i have tried now is to use Ngons/Quads, Mesh Angle 5
and then brought the mesh into Silo and applied a triangulation. My thought
was that then ZBrush must not compute so much when doing polygroups
from normals.

Maybe worth a try, because now i have all small ribs clean. In ZBrush i used
then only keep groups and did not use creases / edges feature.

I am sure your friend can archive much better results.



Regards
Stefan

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Hi all,

In the mean time I've installed ZBrush 2019 and had a go at it.

I have to admit I had higher expectations of ZRemesher 3.0. I guess it's more like ZRemesher 2.2 with sharp-edge support. It doesn't feel like a fully reinvented algorithm. As you can also see in Stefans image there are certain smooth areas where mangled multi-edge singularities occur, in favor of maintaining the sharp edges.

I had hoped ZRemesher 3.0 would make use of Machine Learning to recognize shapes and apply a 'Ground Truth' topology to it.

The rest of the features are of less interest to me personally. I experimented a lot with NPR rendering around fifteen years ago, when finalToon, Pencil+ and Liquid+ were exciting, state of the art 3ds Max plug-ins.

Next to MoI I find my focus centering on Blender more and more since the development of version 2.8. There are a number of free or very affordable add-ons that decrease my need for ZBrush as a companion tool.

I've post a top 5 of Blender add-ons that really help my daily modeling workflow to a separate MoI forum discussion here:

http://moi3d.com/forum/index.php?webtag=MOI&msg=9287.1

Regards,

Metin

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Hi Metin,

i somehow agree with you, but on the other side i have not seen
yet a quad remesher which can replace ZRemesher yet. I doubt,
for example, that 3DCoat's autotopo tool can even handle Michael's
sample model properly. Maybe Marco or you can give 3DCoat with
Michael's test model a try.

I am very very thankful that Pixologic gives us still free upgrades,
so this should be no problem, money wise …

Regarding Blender, yes, it is a DCC app, especially 2.8, which everybody
should take a closer look at.

Best regards
Stefan

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I think the general difficulty is that auto-retopo is targeting generating uniformly sized quads. That works well for the most common organic model type shaping but CAD models very often have a mix of large areas and then smaller sharply defined features.

- Michael

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I agree Michael. It's very complex stuff. I'm hoping that AI will bring the final auto-retopo solution.

Stefan, you're right, ZRemesher is still the best auto-retopologizer in the 3D industry, although 3D-Coat's Autopo can yield very nice results as well, sometimes even better than ZRemesher.

There's also a Blender auto-retopo add-on called Tesselator, which is gradually evolving into quite a nice solution:

https://blenderartists.org/t/tesselator-quad-remesher/1131624

Regards,

Metin

visualization • illustration • 3D design — metinseven.nl

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Greetings fellow MoIists!

Slightly on a tangent, but I came across this guide and it might prove useful to some of you that use Zbrush.

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

Image Attachments:
francis-xavier-martins-tutorial.jpg 

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Sorry but your link no longer appears to be working.

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