 | For this tutorial we are going to use a cartoon-style model of an Ant as a skin.
This model has been provided by It's Ming! It was
modeled with Lightwave.
It's Ming! have a wonderful assortment of
cartoon-style models available at their website. No
distribution of this model is permitted without the permission of It's Ming!
Click here to download the Ant
Model in 3D Canvas format. |
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 | Drag and drop an appropriate skeleton onto the scene from the Skeleton Object Library. You will want a biped skeleton with standard bones. In the default Skeleton Object Library, this
is the first of the two skeletons provided.
Take care to drop it on the scene, not on the skin. |
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 | The next step is to adjust the size and position of the skeleton to fit the skin.
The best way to do this is to have a front view and a side view to work with.
Select View Selection from the View menu. Choose the
icon that indicates two vertical-oriented views.
Right-Click on the left view, and select View->Orthographic->Front
from the popup menu
Right-Click on the right view, and select View->Orthographic->Side
from the popup menu
Using the front view, reposition the skeleton so that it is centered on
the skin with the pelvis in its final position. You will want to move it using its root
bone so that no Inverse Kinematics occur. For bipeds, the lower back bone is the root
bone. Make sure that the skeleton is in front of the skin. At this stage working with a
skeleton that is embedded in the skin is awkward. |
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 | The next step is to resize and reorient the bones to fit the skin.
You will want to have the bones be oriented in the same way as the limbs of the skin, and
the joints in the skeleton match the location of the joints in the skin.
The best approach is to work on one bone at a time starting with the hips and working your
way outwards towards the end of the limbs. First rotate the bone so its orientation is
correct, and then scale the bone so that its length is correct.
You will find that as you rotate and scale bones others will appear to end up in the wrong
position. This is okay since as you continue along the chain these will be corrected. You
may find yourself tempted to correct the size and orientation of bones out of order. Try
to avoid this since it just makes the process more complicated.
To reorient a bone, click on the bone and rotate it using the Edit
Control. Note that in orthographic modes the Edit Control only displays two of the
three rotation axes. The third axis is pointing towards you. You can still use this axis
by clicking the point where the two other axes meet and dragging. You will need to do this
to reorient the bones appropriately.
To resize a bone, click on the bone and scale it using the Edit
Control. While scaling the size of the bone is displayed on the status bar at
the bottom of the window. You can use this to ensure that equivalent bones on the right
and left side of the skeleton are of equal size.
Sometimes a properly sized and oriented bone will protrude slightly from the skin. This
usually happens at the thickest point of the bone. There is no need to be too concerned
about this since the bone will be hidden whenever you play an animation. Just make sure
that the bone is positioned and oriented correctly and of the right length and all will
work out in the end. |
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 | Once you have resized and reoriented the bones appropriately in the
front view, reposition the skeleton so that it is embedded in the skin. As before, you
will want to move the skeleton using the root bone to avoid any inverse kinematics.
Before you do this, switch to wireframe mode. Click on the Primary Toolbar to enter wireframe mode. Once bones are
embedded in an object it is much easier to work with them in wireframe mode.
Now, re-orient the bones for the side view. Re-orienting the bones may also require that
you resize bones slightly for their new orientation. Again, start with the hips and work
your way outwards towards the end of the limbs.
Also, delete the topmost bone from the Skeleton since this bone is intended exclusively
for jointed models. |
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 | Using the Hierarchy, move the
skin onto the root frame of the skeleton.
Click the hierarchy tab on the left side of the window in
order to show the full view of the scene hierarchy. On the hierarchy panel click on the
ant object and drag it
and drop it on to the frame that contains the "Back - Lower" bone. You may
find that you will need to close a few items to make dragging and dropping easier.
This is a critical point. The ant object must be in the root frame of the skeleton so that
skeleton moves when you move the ant. Also, it is important that this be done before you
set the range of effect for each bone.
In this example the eyes are separate objects, so they must be moved to the frame that
contains the skull so they will move when the head moves. |
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 | With this particular model, we want to be able to pose the antennas.
Drag and Drop a standard bone from the Bones Panel onto
the topmost bone. Drag a drop a bone onto the bone just added.
Both bones will automatically have Inverse Kinematics enabled. This means that if you try
to move a bone, the entire skeleton will move using Inverse Kinematics. Right Click on the
first bone added and disable Inverse Kinematics. Move the bone so that it is at the base
of the antenna. Right Click on the bone again and re-enable Inverse Kinematics.
You will notice that we now have a gap between bones. With 3D Canvas this is just fine.
There is no need for bones to connect at a joint. Bones are a type of scene component and
can be positioned and oriented in the same way as any other scene component. |
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 | Reorient and resize the two bones added the last step so that they are appropriate for
the antenna.
Right-click on the topmost bone and choose Properties from the popup menu. Change the
Inverse Kinematics mode from Enabled to Fixed. This will ensure that when either bone is
dragged, only the base of the Antenna will be bent. |
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 | Repeat the last two steps for the other antenna. |
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 | Up until now, the Ant in the scene has been a 3D Canvas Object. We are now about
to transform it into a skin.
Double click on the middle back bone or single-click it and click to attach the Ant object to the skeleton
as a skin.
This will open the Skeletal Bone Range window which allows you to adjust the portion of
the object that is affected by this bone.
All points included within the translucent cylinder will be affected by this bone. The
range of effect of the bone can be adjusted using the sliders.
The Origin Range slider is used to increase or decrease the circumference of the bone's
cylindrical range at the bone's origin.
The End Range slider is used to increase or decrease the circumference of the bone's
cylindrical range at the bone's end.
The Extent slider is used to increase or decrease the length of the bone's effect. |
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 | Repeat the above step for every bone that you want to have affect points.
Keep in mind that bones should overlap so that they share points. This will produce nicer
results during posing.
The shoulders, hips and lower back do not need to have an effect range.
The shoulders do not need to have an effect since they will be wholly enclosed in the
upper back, middle back and upper arms.
The hips and lower back do not need to have a range of effect since all points not
specifically assigned to other bones are automatically assigned to be affected by the root
bone (the lower back). |
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 | Here we have all of the bones with range of effects.
Note that all bones and their range of effect are displayed for easy posing. When you
record an animation or a snapshot, the bones are made invisible. |
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 | We are not quite done however. Due to the way this model is designed, with bent knees,
we have a small gap at the knee. |
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 | As it is, when a skeleton is posed, these unassigned points will not move when the leg
moves. |
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 | The solution is to add a Spherical Bone from the Bones
Panel. Drag and Drop it on to the thigh bone. Then adjust its position and size so
that it fill the gap. Note that spherical bones are only available with 3D Canvas Pro. If you do not have 3D Canvas Pro you can
substitute a short standard bone.
Double click on the new bone or single-click it and click to set its range of effect. Unlike
Standard bones, Spherical Bones' range of effect is the same as the size of the bone. So
any point enclosed in the Spherical bone will be affected by the bone.
We could also have solved this problem by changing the Extent of the thigh and shin bones.
But, that would likely have resulted in too much overlap of bones which usually produces
unattractive results during posing.
Spherical Bones can be useful to add to places where unattractive deformations are
occurring to add just a little bit of weighting to how much the skin is deformed by each
bone. |
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 | We now have a fully posable skinned skeleton.
Click here to
download a model of the Ant with a skeleton attached. |
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 | To pose the ant, simply click on a bone and drag.
In order to show the Ant in a posed state, I have hidden the bones by clicking from the Primary
Toolbar.
To move the whole object without causing any Inverse Kinematics positioning, simply click
and drag the object by the root bone, any exposed skin.
If you want to rotate a bone beyond the range of its Inverse Kinematics joint, you can
simply rotate it using the Edit Control. |
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 | To re-pose the object to its neutral relaxed state, select the skin, and click on
the Edit Toolbar. |
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