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How to convert triangulated OBJ to standart quads thru MeshLab or other software?

wargiswargis Posts: 142
edited March 2014 in The Commons

Hello! Need an advice on modelling for those who had to do with triangulated meshes of clothes and other items. How to convert triangulated meshes of clothing to regular quads? Recently I found Marvelous Designer, extremely useful software for creating dynamic clothes but I attempted to create conforming items and found that grouped triangles cause problems after using them in .cr2 or posing - pokethroughs , spikes etc. (both in Poser7 and DAZ) Obvioisly quads would be much better for conforming and for texturing too. Some people prompted me to use MeshLab for converting from tris to quads through its special filters, but I couldn't find any clear tutorial for this process. My attempts to do it at random led to nothing - after any command from Polygonal and Quads Meshes menu the number of triangles just grows - that's an example of a simple V4 dress -

The original mesh from MD3 -
http://i58.fastpic.ru/big/2014/0317/1c/69c5cc3566b94fdd9a5a25791cdc4d1c.jpg
And a result of conversion -
http://i59.fastpic.ru/big/2014/0317/d3/ed7bc85a52dfd956291f8f3bcb938ad3.jpg
If any of forum users had to deal with similar meshes and used MeshLab - what is the order of actions in conversion?
I guess it's not so straight-forward and I miss some important steps. Or maybe is there any other utility to convert tris to quads, expect from big modeller packages (too big for such limited task).

Post edited by wargis on

Comments

  • frank0314frank0314 Posts: 14,048
    edited December 1969

    Do you happen to have zBrush? Can be done pretty easily in there. Sadly when you convert from tries to quads, you are almost always going to have to do some repairs to the mesh. At least in my experience

  • DogzDogz Posts: 898
    edited March 2014

    On reading your topic title I came in here intending to offer to convert it for you - that was until I saw the screen shot though.


    That kind of generated Tri topology is great for dynamic clothing but it kind of sucks for conforming.
    Generally, these automatic Tri to Quad conversions only really work well on a mesh that was originally made with quad topology - but has since been triangulated. (So its basically for 'restoring' quads more than anything)
    Since that top was never a hand crafted a quad mesh, I'm afraid that what you are trying to do is virtually impossible for most programs.

    Post edited by Dogz on
  • IgnisSerpentusIgnisSerpentus Posts: 2,500
    edited December 1969

    yeah zbrush will do it with qRemesher

  • DogzDogz Posts: 898
    edited December 1969

    I stand corrected, apparently zbrush might be able to do something with it :P

  • Dumor3DDumor3D Posts: 1,316
    edited December 1969

    Hexagon will do this and has been the best I have found at converting every tri to a quad. But, the quads are within the tris and so you still get the triangle bumps showing when posing. I am using zRemesher in zBrush. With a few careful settings and a bit of other work, you can get a good conversion with good topology. I have not yet been able to use the MD thickness and fix one of those. I just add thickness later after fixing the single layer of mesh.

    Like Ignus said, most programs do leave a tri here and there and that is the case with zRemesher. So, you do need to look around and make a few corrections by hand.

  • wargiswargis Posts: 142
    edited December 1969

    Tjanks to all! I see you're right, I've just found several pretty good youtube lessons from MD users about Q-Remesher. It seems it works fast and provides suitable quad meshes, just as I'd like.

  • barbultbarbult Posts: 24,240
    edited December 1969

    Dogz said:
    On reading your topic title I came in here intending to offer to convert it for you - that was until I saw the screen shot though.


    That kind of generated Tri topology is great for dynamic clothing but it kind of sucks for conforming.
    Generally, these automatic Tri to Quad conversions only really work well on a mesh that was originally made with quad topology - but has since been triangulated. (So its basically for 'restoring' quads more than anything)
    Since that top was never a hand crafted a quad mesh, I'm afraid that what you are trying to do is virtually impossible for most programs.


    I'm not a modeler, but I'm interested in understanding why triangles are worse than quads for conforming clothing. Some conforming clothing items I purchased in the store recently were constructed of triangles, and that surprised me. What problems should I look out for with these clothes? Are there any workarounds for those problems, or should I just look for clothes from other vendors next time? (Like Dogz who makes great clothing, with lots of useful morphs, but not enough of it, so I have to buy from others, too :) )
  • IgnisSerpentusIgnisSerpentus Posts: 2,500
    edited December 1969

    dumorian said:
    Like Ignus said, most programs do leave a tri here and there and that is the case with zRemesher. So, you do need to look around and make a few corrections by hand.

    lol Ignis didnt say that

  • DogzDogz Posts: 898
    edited March 2014

    barbult said:
    Dogz said:
    On reading your topic title I came in here intending to offer to convert it for you - that was until I saw the screen shot though.


    That kind of generated Tri topology is great for dynamic clothing but it kind of sucks for conforming.
    Generally, these automatic Tri to Quad conversions only really work well on a mesh that was originally made with quad topology - but has since been triangulated. (So its basically for 'restoring' quads more than anything)
    Since that top was never a hand crafted a quad mesh, I'm afraid that what you are trying to do is virtually impossible for most programs.


    I'm not a modeler, but I'm interested in understanding why triangles are worse than quads for conforming clothing. Some conforming clothing items I purchased in the store recently were constructed of triangles, and that surprised me. What problems should I look out for with these clothes? Are there any workarounds for those problems, or should I just look for clothes from other vendors next time? (Like Dogz who makes great clothing, with lots of useful morphs, but not enough of it, so I have to buy from others, too :) )

    its not so much of a problem for the end user, more of a headache for the content creator. Tri meshed conforming clothing can be rather unpredictable when rigging, they allow for less detail and if you don't have zbrush, trickier to make morphs too (unless they are made with a dynamic simulation), I suppose there are quite a few variables that way, it depends what the clothing item is. But as far as being a customer is concerned, if its on sale here, then it likely works fine, so I wouldn't worry too much... :)

    Post edited by Dogz on
  • Richard HaseltineRichard Haseltine Posts: 100,778
    edited December 1969

    3D Coat will also do auto-retopology, as will dedicated applications like Topogun. For more control, and less expense, you can also do it manually using a background constraint (with the tri mesh in the background) in many modellers.

  • barbultbarbult Posts: 24,240
    edited December 1969

    Dogz said:
    barbult said:
    Dogz said:
    On reading your topic title I came in here intending to offer to convert it for you - that was until I saw the screen shot though.


    That kind of generated Tri topology is great for dynamic clothing but it kind of sucks for conforming.
    Generally, these automatic Tri to Quad conversions only really work well on a mesh that was originally made with quad topology - but has since been triangulated. (So its basically for 'restoring' quads more than anything)
    Since that top was never a hand crafted a quad mesh, I'm afraid that what you are trying to do is virtually impossible for most programs.


    I'm not a modeler, but I'm interested in understanding why triangles are worse than quads for conforming clothing. Some conforming clothing items I purchased in the store recently were constructed of triangles, and that surprised me. What problems should I look out for with these clothes? Are there any workarounds for those problems, or should I just look for clothes from other vendors next time? (Like Dogz who makes great clothing, with lots of useful morphs, but not enough of it, so I have to buy from others, too :) )

    its not so much of a problem for the end user, more of a headache for the content creator. Tri meshed conforming clothing can be rather unpredictable when rigging, they allow for less detail and if you don't have zbrush, trickier to make morphs too (unless they are made with a dynamic simulation), I suppose there are quite a few variables that way, it depends what the clothing item is. But as far as being a customer is concerned, if its on sale here, then it likely works fine, so I wouldn't worry too much... :)
    OK, thanks, I will happily shop away then. I did have an issue where I wanted to use the Polygon Group Editor to hide some polygons, but the triangles didn't allow me to make a smooth edge, so that was disappointing.

  • mjc1016mjc1016 Posts: 15,001
    edited December 1969

    barbult said:
    OK, thanks, I will happily shop away then. I did have an issue where I wanted to use the Polygon Group Editor to hide some polygons, but the triangles didn't allow me to make a smooth edge, so that was disappointing.

    Yeah, as an end user that would probably be the extent of your headaches...but for content creation, Dogz just touched on some of them...there are more. One that is related to what you faced...it is harder to do multiple material zones due to not having clean edge loops/seams to work with.

  • Coon RaCoon Ra Posts: 200
    edited December 1969

    barbult said:

    ... Some conforming clothing items I purchased in the store recently were constructed of triangles, and that surprised me. ...

    They seem to be generated, not constructed. In, maybe, Marvelous Designer with low polygone density set for model. I got a couple, too.
  • DogzDogz Posts: 898
    edited March 2014

    Coon Ra said:
    barbult said:

    ... Some conforming clothing items I purchased in the store recently were constructed of triangles, and that surprised me. ...

    They seem to be generated, not constructed. In, maybe, Marvelous Designer with low polygone density set for model. I got a couple, too.

    Yeah if the topology is a non-uniform tri mesh like the top pictured in the OP^ that's evidently a 'generated' output from the likes MD or the garment maker in 3dsMax etc. Poly modelled / sculpted items will never look like that.
    There is no way to tell before buying a product anyway - as its not common practice on Daz or Rendo for vendors to make a promo showing the topology, its kind of irrelevant I guess, since unlike Turbosquid models and all the rest, most DS/Poser products are not aimed at a user base who can/want/need to edit the geometry. All that really matters to most, is how it renders out of the box. :)

    Post edited by Dogz on
  • Coon RaCoon Ra Posts: 200
    edited December 1969

    Anyway, sometimes it is predictable if a vendor puts a clay render of his clothing model.

  • mjc1016mjc1016 Posts: 15,001
    edited December 1969

    Coon Ra said:
    Anyway, sometimes it is predictable if a vendor puts a clay render of his clothing model.

    That's a big if...not all that many clay renders around.

  • ghastlycomicghastlycomic Posts: 2,531
    edited December 1969

    dumorian said:
    Hexagon will do this and has been the best I have found at converting every tri to a quad. But, the quads are within the tris and so you still get the triangle bumps showing when posing. I am using zRemesher in zBrush. With a few careful settings and a bit of other work, you can get a good conversion with good topology. I have not yet been able to use the MD thickness and fix one of those. I just add thickness later after fixing the single layer of mesh.

    Like Ignus said, most programs do leave a tri here and there and that is the case with zRemesher. So, you do need to look around and make a few corrections by hand.

    Wait.... Hexagon converts tris to quads? I did not know this. How do you do it?

  • frank0314frank0314 Posts: 14,048
    edited December 1969

    Most modeling apps will transfer quads to tris but not sure about the other way around

  • wargiswargis Posts: 142
    edited March 2014

    Thanks, folks, I tried to use Zbrush and found QRemesher a really cool retopo tool! But there is a well-known problem with UVs, which I dream to keep as near as possible to the original MD layout. After retopo and manual unwrapping most of the new maps come out distorted and wavy, not so accurate as in MD. In their forum I stumbled upon a phrase about one possible decision -
    Zbrush should still be useful. Just output the meshes flat, then run the quad mesher on them. Then the UVs can be projected straight from the originals to the new quad mesh. Then the new meshes can be wrapped back into it?s 3d form. using the same UV projection.

    I got the first part - exporting a flattened mesh from MD (resetted to Default Arrangement), then I need to remesh it and export as a new quad OBJ. I did it and got the quad flat mesh with a very precise unwrapping -
    http://i59.fastpic.ru/big/2014/0320/88/c739de1337b9997f1e97a87c3e0ab688.jpg
    What for the second part& How can I do it in Zbrush - projecting UVs from the first flat tri mesh to the new quad mesh? And how to wrap the new Uv-mapped meshes to 3D? The only similar advice I found was for Maya - thru Transfer Attributes. I never used Maya and I suspect there is a similar way in Z-Brush. In that thread nobody explained this secret, but I found one plugin from EZhexagon (QRemesher-guides) and some videos (especially this one - it shows how to flatten a triangled mesh through UV-Master, and remesh it to quad in a flattened state. Сan it help to keep Uvs? I tried to make it with meshes and turn them back in 3D shape - it't doesn't work.
    What can be done in Brush to transfer Uvs in their MD's state to the new remeshed quad model? (If it's possible there at all). Can the plugin (QRemesher-guides) help it? I'm a total newbie in ZBrush and its tools and UI - such a puzzle...

    Post edited by wargis on
  • none01ohonenone01ohone Posts: 862
    edited December 1969

    Blender in Edit mode.
    Mesh/Faces/Tris to quad.

  • fictionalbookshelffictionalbookshelf Posts: 837
    edited December 1969

    ghastlycomic said:
    dumorian said:
    Hexagon will do this and has been the best I have found at converting every tri to a quad. But, the quads are within the tris and so you still get the triangle bumps showing when posing. I am using zRemesher in zBrush. With a few careful settings and a bit of other work, you can get a good conversion with good topology. I have not yet been able to use the MD thickness and fix one of those. I just add thickness later after fixing the single layer of mesh.

    Like Ignus said, most programs do leave a tri here and there and that is the case with zRemesher. So, you do need to look around and make a few corrections by hand.

    Wait.... Hexagon converts tris to quads? I did not know this. How do you do it?

    I would like to know this too and if it's possible in Silo

  • frank0314frank0314 Posts: 14,048
    edited March 2014

    In SIlo once you triangulate then it can't be converted back to quads. The app modeling in quads by default You can't even model in tris. If you want tris you have to model in quad then convert to tri

    Post edited by frank0314 on
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