Avastar: -6- Weighting

So you came here to learn more about weighting? Then you have found the right place!

If you are not comfortable with rigging and with the details of the Avastar armature, then i recommend to first watch theĀ 
Avastar Rigging tutorial

There are a couple of manual and even automatic possibilities to create good weight maps for your rig. The first and most commonly known tool is the weight paint brush. You find it in the tool shelf. Here you can select between add, subtract, blur, and some other brush types…




So you came here to learn more about weighting? Then you have found the right place!
There are a couple of manual
and even automatic possibilities to create good weight maps for your rig.

The first and most commonly known tool is the weight paint brush.
You find it in the tool shelf.
Here you can select between add, subtract, blur, and some other brush types.

Let us tryout some brushes to get our dress into a better shape,

Note that you can select a weight value for your brush here.
the exact meaning of this value depends on the used brush.
Especially for the add brush and the subtract brush you will probably want
to set this to very small values around 0.1 or even lower.
I also adjust the brush radius to my taste,
and i set the brush strength to about 1 for now.
You will have to play frequently with these values.
Otherwise the brush strokes might become too strong and you can quickly break
the entire weighting.

Lets start near the hips where we apparently see the worst distortions.
We switch the active bone frequently during our painting session,
and thus we try to improve the weighting for all involved bones.

However, we see after a while that its not so easy
to get this weighting fixed
with the weight brush alone.
But hold on,
until now we have weighted each bone separately,
but we can enable multi paint mode in the tool shelf.

This mode works very well with the blur brush.
Now the weights get averaged over all involved bones,
and that often helps to get smoother results.

But even the multi paint brush does not work in all cases.

So there is another tool available for us.
We can try automatic weighting.
Simply select a bone, then press “w” and select “automatic”.
You can switch to other bones and try automatic weighting again
and see if you can get improvements.

While you often can get some decent overall results with this method,
you might sometimes still end up with some parts that just do not want to get right.

In that case you can use the selection masks.
and try again to use the weight paint brushes.
Enter face selection mode.

Now you can use right mouse click to select single faces,
or shift right mouse click to add more faces to the selection.
Or you can use the rubber band tool by first pressing “b”,
then select the area of faces by left mouse click and dragging the mouse.
You also can deselect areas by using the middle mouse button and dragging.
You terminate the rubber band selection by releasing the mouse button.

Now try to add or subtract the weights as needed.
the brush will only influence the selected faces.
please note that also automatic weights will take care of the selection.

So you can for example modify only the dress border as follows:
select only the lower border of the dress.
now press “w” and select automatic.
this helps often to get the borders smoothed.

But we still have a few remaining issues with our mesh.
lets take another look at the lower border of the dress.
We want to make it fall down a bit smoother
and it should fit more tightly to the raised hip.

Neither automatic weighting nor the brush could help us here.
So now we have to get into fine tuning.

go to object mode.
select only the dress.

Now go to edit mode.
You see that the mesh snaps back to its rest position.
So lets enable weights in edit mode.

Open the modifier stack.
Select the editing icon.

Now another icon appears.
select it as well.
Now the mesh can be directly edited.

Select one single vertex.
open the properties panel.
locate the vertex groups panel.
Now you can modify the weights of this single vertex.

Often you will see immediately what causes the particular problem.
Sometimes you have to try a bit until you find a good solution.

It is important to know that these weight values
are not used directly, they are used to calculate
a percentage of influence for the involved bones.
For example if you set all weights to the same value,
then the weights are distributed equally over all bones,
regardless of the value itself.
But note that a weight value of zero
will remove the influence of the related bone,
but you can not set all weight values to zero at the same time

In practice i found that in many cases wrong behaviour of the mesh
comes from weight values close to zero.
In such cases the mesh often improves by setting the value to zero.
Also note that there should be not more than 4 vertices in the list.
this is a limitation of OpenSim and compatibleonline worlds. It is not known what happens if
the number of weights per vertex go above 4. Actually i never found
any problems related to this limitation.

So this is a very powerfull tuning option in blender.
And you almost always can quickly solve your weighting issues.

but there is yet another sort of issues.
Sometimes you might try to tune a particular vertex,
but just do not get it right whatever you try.
in that case you may need to tune the mesh itself as the
last rescue.

Simply select the vertices that look wrong,
and move them in edit mode.

But please keep aware that you now modify your
mesh, so you should only do very small corrections,
and you should only use this method when weighting just
does not want to get right.

Of course you can use the vertex group editing
and the direct vertex moving at the same time.

And although we now are operating on vertex level,
we still can run into more problems.
In this case for example our mesh does not have enough faces.
this sort of problems can often be fixed by adding edge loops.

So after some tuning and moving,
your mesh begins to look as expected.
Now its time to change the pose
and check if your modifications also work
for other poses.

one easy trick is to check the mirrored pose as follows.
go to pose mode,
select all bones,
copy the selection to the bone copy buffer,
then paste to the opposite side.
and now continue your mesh weights tuning.

During this process you will have to test your
weighting with several poses. Your best option
is to start with the rest pose, then move the
bones until you find an apparent weighting issue.
then fix that issue and finally advance to the next pose.
You should try to get your weighting as good as possible
for the rest pose,
and you should not spend too much time on extreme poses.

But i believe that after some practicing you
will get reasonable results for your weighting.
Please be patient and start over again if you fail.
After all weight-painting is an art by itself.

I hope that this summary helps you
to get your mesh attachments into
a nice shape.

Thank you for watching.

12 Enlightened Replies

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Sites That Link to this Post

  1. Quantum Grids | Creating Clothes for Avatars in Open Sim | March 27, 2015
  1. Franklin kozlov says:

    I also have this problem and cannot solve it you did???

  2. Qutea says:

    Hello, while I followed practically all these steps. I found myself in a pinch. – I went to export into a Collada, but this message error continuously pops up. – I’m not experienced enough to fix this issue. Any feed back would be appreciated.

    —–Below is a picture of the error—-


  3. manu reggiane says:

    no automatic weight when i press w after selecting a bone

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