Skinning

Skinning is the process of connecting geometry to the rig, it uses values between 0 and 1 in which 0 and 1 correspond to tone, with 0 being white and 1 being black, and decimal numbers making up the mid tones. One of the processes we will cover in this lesson is various forms of weight painting including the connection editor, weight painting with the brush, and the interactive weight paint.

There are two different kinds of binds, the Hard [rigid] bind, which can be either on or off [1 or 0] this is better for hard surface modelling, and the Soft bind which uses gradients for more organic movement.

To begin with, Hide the left_arm_layer in the display by toggling off the V.

 

We will need to test to see how the joints move, to do this we will need to add an animation to test the limits of the joints, this makes it easier to scroll through a timeline than manually move joints. First, on the timeline, every 10 frames pick a joint. For the shoulder, move  the cursor to frame 0, right click on rotate y, and click key selected. On increment 10, move rotate Y to 100 degrees and then press key selected, then for increment 20, reset the rotate y to 0 and key selected. Now when you move the timeline, the arm should move. We will now need to repeat this step for each joint, below is the specifications for each joint.

elbow

right click on rotate y, click key selected

0 - key selected

10 - move -100 degrees key selected

20 0 - key selected

wrist

right click on rotate z, click key selected

0 - key selected

10 - move -60 degrees key selected

20 0 - key selected

Finger joints

right click on rotate z, click key selected

0 - key selected

10 - move -10 degrees key selected

20 0 - key selected

Thumb

X axis for the thumb joint

-90 degrees

Duplicating Keyframes -

You can duplicate Keyframes by shift and dragging over your keyframes and pulling them over to your next spot in the timeline. This makes the process go by much quicker.

Weight Painting -

Switch from your modelling menu to the Rigging menu and then find the skin menu along the top, there are various options for skin weights but for now we will need bind skin, and paint skin weights.

Later on however we will be using the component editor which can be found under the Windows tab, general editors and then component editors.

To bind the skin to the joints, first unhide geometry, this will work similarly to  parenting by selecting and joining elements together. Under the skin menu select bind skin, this will connect joints and the geometry and will also add colour indicators to the joints. Now when you play the animation the skin and the rig will move, this is the basic bind. From here, we will need to adjust the settings in the bind skin. Under the bind skin menu there is a slider for max influences, change it to 1 and apply to rig and skin. This is a rigid bind

Component method

The component method is the most rigid and secure method of weight painting but can be more complex to understand. To make things easier on ourselves first put your component editor on one screen and your rig on the other. It is best to work with your model unsmoothed, so press 1 to unsmooth. There is a smooth skins tab on the top, select it, then go into the attribute editor and locate the skin cluster 1 max influences option and set this to 3. Now that you have done this, lock the joints in the display menu and go into vertex mode, selecting all vertices on the upper arm. The vertices selected should show up in the component editor screen. They should all be set to 1 initially, the total should never be more than one in the total box. It is also to note that vertices are colour coded to the joints they're attached to. Beginning with the pinkie finger, select all vertices on the pinkie knuckle [in a ring], you will see that currently these vertices are shared between two joints. We will be performing a process called weight normalization to fix this issue. To do this, select all of first column [vertical] in the component editor and set to one, then do the same for the next joint below it [go to joint 2 column and set to 1]. Then,  go back to the top joint and select all of joint 2 column in the component editor, set all except the third one from the bottom to 0.5. Moving onto the middle joint, find the joint 2 column in component editor and set all except the third one from the bottom to 0.25. Now, do the same for the bottom joint you selected. Now when you move the timeline slider, the finger skin should warp in a more natural fashion.

Weight Painting

Weight painting is another method to perform this function. You will need to locate the skin dropdown and then the paint skin weights menu. You will be presented with a brush function, which much like Z brush you can use the keybind b to make the brush bigger or smaller. On the left hand side, the tool settings is where all the options and joint components are kept. Before you begin painting, you will need to lock all joints that you dont want to work on currently.

In this case, we will be working on the elbow so lock all the wrist  and finger joints. The tool menu should look like the image below.

Start off in replace brush mode and set opacity and value to one, once you have done that find and press the flood button. Like stated before, tone is dictated on a scale of 0 to 1 with decimals making up the gray tones in-between. We will first need to set our value to 0.5 and set our mode to add. Selecting Shoulder int, find the center line around the elbow, making your brush size smaller and painting around the joint. For the vertices below the elbow joint set value to 0.25 and go around and for vertices below the elbow joint [shoulder] set value to 0.75 and go around. For the top bit, set to one and colour in up to the joints making sure not to cover vertices youve already done, it might be worth changing the brush mode to replace rather than add at this stage to ensure that you dont end up adding together the values. It should end up looking like the image below.

We can then use this method for the lower half of the arm too as well as the wrist and fingers. This method is much less tedious than the component method and still allows for more natural movement of the joints and skin, however it takes a bit of fidgeting with the painting to get everything to look right.

interactive bind skin

The final method you can use is the interactive bind skin method, this method has a heat map that you can expand and alter to your liking and works very similarly to the base weight painting method. It offers less overall control especially with finer details but is much quicker to do.