Fitted Mesh

Since there is currently so much talk about liquid mesh i thought maybe i put together some substantial facts about this topic.

What is Fitted Mesh?

So, what is Fitted mesh, Liquid Mesh, Flexi Mesh, Redpoly mesh, weighting to Collision volumes , … ? These and a few more terms are flying around since some time. But actually all these things describe the very same basic technique, that is:Weighting the avatar skin to the “Collision Volumes”.

More technical details about the Avatar skeleton and the Collision Volumes are explained in The SL/OpenSim Skeleton

Avastar Support for Fitted Mesh

new Collision Volume Bones

Avastar has been prepared to work with 7 new bones for Fitted Mesh:

  • BUTT

Avastar also uses the up to date Character definitions from Linden Lab. So it should be well prepared. Please download the newest Avastar version from the Testversions subfolder of your personal download page.

Shape Sliders for Custom meshes

This feature exists since a long time in Avastar, but it never worked reliably. Recently we have started to enhance this option. Currently (1–december-2013) it works reliably ONLY for the default Avastar (male or female). Here is a short workflow:

  • Reset your Avastar to default settings
  • Rig your attachment to the default Avastar character.
  • If for ANY reason you wish to test fitted mesh on the Avastar character, then freeze first!!!
  • Weight your attachment to the default Avastar character
  • “Attach Shape Sliders” (Only attach your custom mesh, do NOT attach the Avastar meshes them self!)
  • Now the Shape Sliders also work on your custom mesh SIMILAR to how they work in SL

WARNING: If you attach the sliders when your character is NOT fitted to the default shape,
or when you attach the Avastar meshes them self to the Sliders, then you will get a disaster.


Technical details

What is the “original” purpose ?

The Collision Volumes are used as very simplified model of your avatar shape. This simplified model is “officially” used for calculating the collisions of your avatar with other objects and characters.

How does it work ?

The collision volumes are best explained as 19 additional octahedrons hidden inside your character. Here are their properties:

  • They have an adjustable length (from tip to tip) and thickness.
  • Their shape is modified via the SL shape sliders.

Thus the set of Collision Volumes always gives a rough approximation of your Avatar shape. This approximation is enough to calculate interaction of your avatar with other objects and characters.


How is all of this related to Liquid Mesh ?

Technically the collision Volumes have been implemented as (hidden) Skeleton bones. Since every bone can be weighted, this is also true for the collision volumes. And as a lucky coincidence the change in thickness of the collision volumes is transferred to the avatar skin (when the collision volumes are weighted).So it is this discovery that made “Fitted Mesh” come to live and work as you can see in all “Fitted Mesh products”.

What are the limitations?

The 24 collision volumes are distributed over the avatar such that they give a good approximation of the entire avatar shape. But this approximation is not very detailed. For example all shape modifications on the face are actually reduced to one single collision volume.Note: the head is approximated as an octahedron, see image above. Also the torso contains only 3 Collision volumes. And unfortunately the breasts are not(!) approximated, so no liquid breasts here…


10 Enlightened Replies

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  1. tenly says:

    Hi, Ive been looking all over your blog and google and cant find help with avastar. I purchased it for making clothing. But I see all the videos do not give examples of how to set up and get started. I mean I do not expect you to show me how to create everything. but a simple tutorial maybe with a simple shirt as an example of how to set up avastar and get going so I dont start out wrong would be great.

    So far I know I can put a avastar avatar on the stage. not how to use avastar to make clothes. do I put it on a separate layer? so I build clothing around it and then use avastar to attach that to the bones for rigging? maybe the answer is yes, but I dont know step 1, step 2, etc.

    Right now I cant see how avastar even helps in that venue. and Im certain this is because of my lack of knowledge.

    Can you please point me, can anyone point me to a few help videos for something like a wee shirt from start to finish using avastar? Doesnt have to be a shirt. just thinking that cuz it covers several joints…

  2. Brue Gothly says:

    Hello Gaia!

    I was directed to your blog to retrieve Doc Toyoko’s avatar file for use with MD, however, I’ve searched and searched, but cannot find where to download them. Are they still available through your blog, is this a case of right in front of my nose? LOL.

    Thanks for your blog!


  3. JJLater says:

    I’ve been all over your tutorials and can’t find what I’m looking for. I’m making mesh clothing and have tried to make fitted mesh versions. When ever I export my blender mesh to DAE and try to import it into the SL Beta Test Grid, I put on the item and it distorts my avatar into a mess. My head is on the ground, my arm is twisted and in the wrong place, etc. I’m not sure what I’m doing wrong on my export from Blender or my Import to SL. I’ve searched and searched and there is a lot of tutorials on how to rig the new fitted mesh, but nothing I can find about how to get it into Second Life without these troubles.

    The standard classic mesh still works fine for me. So, I’m still creating my work that method for now. But I would love to get a handle on this fitted mesh mess.

    Thank for any help or direction you can give.

    • Gaia Clary says:

      I suspect you try to upload your meshes with joint positions. this seems to be not supported by Second Life.

      If you are not using Avastar, then please check out the fitted mesh survival kit on our Blog. There you find detailed information about how to get your meshes exported correctly out of blender.

      Also there is a chat group dedicated to Avastar users in Second Life. You can join this group “blender avastar” and most probably you will get help from there.

      • JJLater says:

        Thank you. It must be what I’m doing. I knew I had to be doing something wrong in the uploading process or the exporting options in Blender. I appreciate your quick response.

  4. Wow sounds good waiting for a tutorial so I can be sure I have best workflow. Thanks for a great tool Gaia, this is a time saver and also makes life so much easier. I forget how fun it is working in blender as well.

  5. Coby Foden says:

    Thank you for the information. 🙂

    (Oh, psst.. by the way…
    it’s Linden Lab, not Linden Labs


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