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…


12 Enlightened Replies

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  1. deepelements says:

    I’ve uninstalled Blender 2.79 and installed version 2.77, to be more compatible with Avastar 1.7. I’m also going to start over. But, do you think that I needed to “generate physics” or anything for this mesh tank top? Does it require additional weights?

    I will let you know what comes of my efforts 🙂

  2. deepelements says:

    Hi, Gaia. Your posts and YouTube videos have been so incredibly helpful and I’ve learned a great deal about how to create mesh clothing for second life, using Marvelous Designer. But …. I need some help !! Please 🙂

    My end product had distortion on various places, noticeably the shoulders and the lower front. I’ve attempted weight painting and various manners of updating or modifying the weights…to no final success.

    I’ve exported it from MD (Ver 7) to Blender 2.79, after important my Avatar by shape using the Avastar Plugin (ver 1.7). The posing rings around my avatar do not automatically display on my avatar, so I go into the avastar settings and choose pose to show them, then switch them to object view. I clear all selections and choose the shirt, then holding Shift I select the armature (rings) and then I bind to armature using the avastar tab. It is rigged, and the weights are said to be from the mesh. When I check the weighting, it looks like it’s weighted normally from each bone onto the shirt.. The shirt does move with the body in pose mode.

    When I upload into Second, it is distorted and looks improper on the shoulders, and some toward the bottom. In the upload window, the item appears fine. But, I can preview the distortion before uploading by clicking the skin weights in the preview window and then I see the distortion. So, I’m assuming it must have something to do with the weights..

    Another variable that I think exists i that I notice there is weight mapping on the opposite side of my tank top, where I can see a different set of shaded colors on the inside that is unaffected by weight painting happening on the outside of the item. But, when I flip it I cannot see any differing weights.. The inside is transparent and I’ve tried BOTH using solidify modifier, and not using it. There is always this occurring distortion…

    Any help you can offer would be a blessing!! I’m more than happy to provide anything you need 🙂

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