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I am very noob with Blender. I started playing VRChat and discovered that we can create our own avatar.

I had 0 skill with Animation programs, but I watched some tutorials on how to upload my own Avatar model to VRChat.

So I downloaded an Avatar from the net, used Unity to upload it to VRChat and successfully did it right, but there was no lip sync.

Therefore people advised me to use blender to do that, so I downloaded Blender and imported this avatar to it: I noticed that it has over 40k polygons which is double the polygons that Avatar needs to be to be uploaded to VRChat.

The problem is that the whole body including head, body, hands and legs are under one mesh, but I want to reduce only the body's polygons so that the face doesn't look messed up in the Chat.

Is it possible to separate the head from the body and have it separated mesh so that I can decimate only the body without changing the head and by keeping everything in tact without messing something like the bones and/or the lip sync ?

I will be very appreciated if someone helps me with that.

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    $\begingroup$ yes you can "separate the head from the body" but you'll want them to be connected again, and that will be difficult because you'll have reduced much geometry only on one part... I would try to keep it as one mesh, but act on different parts (imho it needs experience). Blender has a "decimate" modifier that can act mainly on some specified (vertex groups) part of your model, but it deeply alters your model's geometry... If it was mine, I would try to act manually, to be sure to not alter too much the original shape and geometry. If you can post an image of the model (editor > image button). $\endgroup$ – m.ardito Jan 6 '18 at 10:43
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    $\begingroup$ Sounds like instead of decimating, you should dissolve unneeded edge loops. Keep your topology manageable and still reduce your poly count. $\endgroup$ – Mentalist Jan 6 '18 at 15:06
  • $\begingroup$ Thanks m.ardito and Mentalist for your replies. It sounds complicated to me, to be honest as I mentioned, I have like 0 skills about blender specially that I need something a bit complicated. Anyway, here is the link to the model I am trying to decimate deviantart.com/download/714687339/… $\endgroup$ – Thomas Klima Jan 6 '18 at 16:17
  • $\begingroup$ BTW I was able to reduce the quality of it using Unity, but as I mentioned above, because the head is in the same mesh as the body, I couldn't only reduce the quality of the body alone, and this led me to have a bad looking face of the model inside the VRChat itself. If I can just keep the same quality of the face and ignore the other part's qualities which aren't that important, I would be more than happy. P.S.: The Tris number is over 45000 , it has to be less than 20000 to be uploaded to VRChat. Thank you again! $\endgroup$ – Thomas Klima Jan 6 '18 at 16:17
  • $\begingroup$ I tried the above link but it gives me a non-existent page... if it's a paid model, it could be not available to others... $\endgroup$ – m.ardito Jan 7 '18 at 10:14
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I'll try showing you some simple way to simplify (by hand) your model body: I downloaded a full body human mesh from this site.

The archive is compressed with .rar format, so you have to unrar it before (it's like a .zip archive, just different): find a suitable program for your computer system (eg: http://www.7-zip.org/, free and open source).

The extracted model itself, is in .obj format so you can't open it in blender directly, you have to import it: blender has a "Wavefront (.obj)" importer by default, use it with default settings, it works well.

You get this model:

enter image description here

how to simplify it body without touching its head?

example: select a "loop" of vertices (this is a particular one that goes over all the model'storso)

enter image description here

how to?

select two vertices sharing an edge, like in the picture below,

and in edit mode use the

mesh > edges > edge loop

you can also get the same menu floating, like in the picture, using the shortcut CTRLE

enter image description here

anyway you can select loops in any way, with the many selection tools of blender...

tip: a useful simplified way to select a loop is to select one of its edges while keeping pressed the ALT key (and, as always, SHIFT if you are adding to a previous selection)

now the loop is selected,

enter image description here

now press X to get the "delete" menu, and use "dissolve edges"

enter image description here

and you get

enter image description here

you can also "dissolve" several edge loops together:just leave some loop between them, like here:

enter image description here

and you'll simplify it faster

enter image description here

that's it, you reduced you vertex count without ruining your shape!

you can do this on arms, legs, torso, just be sure to do it simmetrically, and just where it don't alter too much your body shape and... don't loose your head :))

Hope it helps.

edit:

after importing your real model into blender (using mmd_tools addon), I saw it's quite dense, but made of triangles instead of quads...

enter image description here

as said below in comments, loops work only on quads, but fortunately blender can convert triangles (tris) to quadratic shapes (quad) - 2 tris become 1 quad. with this menu command:

enter image description here

after which you get your model almost entirely in quads

enter image description here

Then I noticed another problem: there are doubles (how I noticed? some loop was still not working, so I guessed that... experience)

So you have to remove doubles first: in edit mode, press W to get the "specials" menu and press "remove doubles"

enter image description here

you see there were some

enter image description here

Now loop tools work as expected, and you can try my suggested path above

enter image description here

You may have noticed that converting 2 tris to 1 quad has reduced total faces count (of course) from about 45k to 25k. But exporting back your "quad" model to pmx, triangles will be restored by the exporting process (so 1 quad will become 2 tris). So, based on your question info, you'll have to reduce your "quad" model below 10k quads, acting on body obnly, I guess. It's a lot!

I also noticed your model is fully rigged, so it could be ready to be animated in VRchat? ...if yes, of course, reducing body vertices could make it move differently than intended, who knows.

It's not as easy as those people that advised you to use blender thought perhaps. It can be done, imho, but it will require a lot of tries and patience, and restarts if it becomes a mess...

Last, about this comment: "Is there a possibility just to make the head in a different part of the body's part so that I can decimate only the body using Unity? Because I have nice Unity plugin for reducing the Tris but need to make the head a different part or mesh than the whole body. "

you can split your mesh easily in blender, too. select head vertices, the press p, and select "selection", Done. And you can act on body only. But if you later need to join that head with the simplified body, it will be worse. And if the model is to be animated in VR chat, using the full armature that the model has, it will be even worse, trust me...

But you can try different things, at least!

edit2:

about your last comments, and the fact that you can't reduce much triangles... yes, it is impossible to get below 20k triangles if you don't want to edit the head...

enter image description here

as you see, your head alone (selected) is made of over 12.2k quads, ie: around 25k triangles... that does not deend on blender tools, it's just how this bee is done.

If you want to go below 20k for the entire model, you must edit the head also... sorry...

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    $\begingroup$ I am speechless after your answer, I really can't thank you enough for this awesome explanation. Thank you very much. I will try and follow your steps carefully and hope I won't ruin the model. BTW about the link, weird it was working yesterday, it is a free model, but maybe because the site requires registration. Anyway I uploaded the file to google drive in this link if you are willing to check it out drive.google.com/file/d/1TaflwseoA6rY5T1JoFj2j4SjAy0XI2vu/… Thank you again and again for your help and time! Best regards! $\endgroup$ – Thomas Klima Jan 7 '18 at 21:44
  • $\begingroup$ You're welcome! Not needed at all, but if you think this helps you, consider upvoting my answer (see near answer title), and if it solves you issue, you can also mark it as accepted. This may help showing other users what is useful, what solves an issue like yours. Have fun! $\endgroup$ – m.ardito Jan 7 '18 at 21:50
  • $\begingroup$ I followed also your steps, they are nice but I couldn't reduce the "Tris" number that much. Is there a possibility just to make the head in a different part of the body's part so that I can decimate only the body using Unity? Because I have nice Unity plugin for reducing the Tris but need to make the head a different part or mesh than the whole body. Best Regards! $\endgroup$ – Thomas Klima Jan 8 '18 at 5:11
  • $\begingroup$ I have now your "bee" model in blender. Te problem is that this model is made of triangles instead of quad (better topology, as the model I used above). Loops work only on quads. I'll try to find something easy for you. $\endgroup$ – m.ardito Jan 8 '18 at 8:20
  • $\begingroup$ Edited answer with more info, using your model. $\endgroup$ – m.ardito Jan 8 '18 at 8:56
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M.ardito answer is a really good option. Use his method if you want a precise editing done by hand. It will take time and patience, but you will surely get a good result. I have instead a more automated method, limited dissolve, which is more rough (and evil).

Since you said you don't have experience with Blender, I'll show every step (I used a model made in 5 seconds because your link doesn't work):

Step 1: Press tab to enter edit mode (or click on Object mode and then select Edit mode)

Object mode

Edit mode

As you can see from top right, my cube has got 30730 vertexes.

Step 2: Press "A" to select all the vertexes

All vertexes selected

Step 3: Deselect the parts you don't want to simplify

Press "C" to select the Circle select tool. With this on, click middle mouse button to deselect.

Circle tool

You may find difficulty selecting some vertexes, for example if some parts overlap or are near. To workaround this, you can hide vertexes, by selecting them and pressing "H". If you want to show them again press "Alt"+"H". You can also use vertex groups in the object panel to help you:

The vertexes groups panel

Choose the method which you find most comfortable. In my case, I would select with Circle tool the vertexes I don't want to simplify, hide them, see if I want to change something, unhide them, add/remove vertexes, and once you have all the vertexes you don't want to be optimized press "Ctrl"+"i" to invert the selection, and proceed to next step. Notice that you can change the circle tool size by moving your mouse wheel.

Step 4: Simplify

Once you have all the vertexes you want to delete selected, go as shown in the image to "Limited dissolve":

Limited Dissolve

The Limited dissolve tool optimizes based on an angle, see next image (if you don't get this menu, move the mouse cursor to the screen where your character is, and press "T"):

Options for limited dissolve

As you can see it optimized my vertexes to 40. This is both minimal and maximum optimization, because there were no angle at which there were more or less vertexes, my cubes basically had 6 faces each, with no curves, just some straight 90 degrees angles, so the tool gave me this result. With your character instead it will work better, optimizing the position of the vertexes. I recommend not going under the 20000 vertexes you said, since it may cause problems to the rigging system (I actually never tried this on a rigged object). Keep changing the max angle according to that. I hope this solves your problem :) .

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  • $\begingroup$ Thank you F. Alessandro for this great post, so this is another method and I have to pick one. Thanks! BTW I posted a new link by myself in the comment under M.ardito's method, is it also not working? Or did you mean the first link? Yes the first link isn't working anymore. Best regards! $\endgroup$ – Thomas Klima Jan 7 '18 at 22:46
  • $\begingroup$ No I completely missed the other link, and this one works. Thanks for making me notice. $\endgroup$ – F. Alessandro Jan 7 '18 at 23:10
  • $\begingroup$ I did your steps. But maybe you understood me, actually I want that the Tris number (and not the Verts) to reduce from 45000 to 20000 or else I couldn't upload it to VRChat. After I followed your steps, and deselected the whole head, the arms and the legs, and left the body selected, then applied the last step ( Mesh --> Delete --> Limited Dissolve ) the "Tris" number has been decreased from 45000 to only 43000. Is that normal? $\endgroup$ – Thomas Klima Jan 8 '18 at 1:54
  • $\begingroup$ Here are screen shots of what I did... Before: photobox.co.uk/my/photo/full?photo_id=500474520902 After: photobox.co.uk/my/photo/full?photo_id=500474520904 $\endgroup$ – Thomas Klima Jan 8 '18 at 2:07
  • $\begingroup$ I can't see the photos. Whenever I click on them it redirects me to "photobox.co.uk". Anyway have you tried changing the angle? I can't convert the 3d model to try with my own method. Maybe you can upload your .blend file on "blend-exchange.giantcowfilms.com"? $\endgroup$ – F. Alessandro Jan 8 '18 at 16:20

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