Advanced Skeleton Maya
Apr 08, 2013 How to rigging a character with advanced skeleton in maya. How to rigging a character with advanced skeleton in maya. Skip navigation Sign in. If you're new to Maya. Technical director Oyvind Nostdal developed Advanced Skeleton to make character creation a much more efficient process. AdvancedSkeleton is a collection of Maya tools for doing character setup. Main Features:-Unlimited body configurations, 3 heads, 5 legs, 100 fingers, & anything goes.
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Advanced Animation Controls In this section, you add some more complicated controls to your character rig. This process involves using math functions to create automatic torso motions, setting driven keys to create a rolling foot control, creating an advanced backbone with spline IK and clusters, and creating color indicators that warn when a control has been moved too far. Although these controls require more time to set up, they make it easier and faster for you to animate your character. Some of the expressions used in this section use expression functions. An expression function is a predefined command that can be used in an expression instead of explicitly writing the complicated math associated with the command.
Some common expression functions used in Maya are abs, trunc, cos, rand, and time. You can view a list of functions in the Expression Editor under the Insert Functions menu (see ). To view a complete list with detailed explanations of each function, look in the Expressions section in the online documentation of the Help menu. You can find a list of the advanced expression functions on the menu bar in the Expression Editor. Constraining the Torso to the Feet One thing that can be useful for easily moving your character around in a scene is to connect the torso to the feet with an average expression. This always keeps the UpperBody icon between the two leg boxes whenever they move in X and Z.
In addition, you create an expression to make the torso automatically dip in Y each time a foot takes a step. The amount of the dip is based on the size of the step (see ). Add expressions to make your character's torso automatically move when each foot takes a step. Keep in mind that although these expressions make certain actions easier to animate, they may not be appropriate for all scenes. Sometimes you will want to disable these expressions and animate these motions manually. This is especially true if your character is going to rotate extensively from the Rig node, such as to perform a 360-degree flip.
This is because the Rig and Feet nodes, which are parents of the nodes involved in the expressions, cannot be affected by the upper body and leg boxes. The reason for this is that having a child node affect a parent node causes a cycle, which generates an error message from Maya. Because this is undesirable, using the expressions causes the Rig and Feet nodes to get left behind as soon as you begin moving your character around using the average expressions. In turn, this causes the pivot points to be off for any kind of body rotation using these nodes. Exercise 3.12: Creating Torso Averages and Dip.
The first step in constraining the torso to automatically move when the legs move is to create a couple of group nodes that are sitting directly on top of, and are the parents of, the UpperBody icon. If you constrain the channels of the UpperBody icon directly with these expressions, you will no longer be able to manually animate the upper body of your character. Instead, you constrain the channels on some parent group nodes that propagate the movement to the upper body through the parent child relationship. You can then manually add keyframes to the UpperBody icon in addition to the automatic movements.
The term often used for keeping the channels of a child node open for setting manual keyframes is a freedom node. In the hypergraph view, select the UpperBody icon, and press Ctrl+G twice. Name the top group node UpBodAuto1, and the lower group node UpBodAuto2 (see ). If your UpperBody icon was originally placed right on top of the Rig node, your two group nodes should be sitting right on top of the UpperBody icon. If not, go into insert mode and move accordingly.
Because you are going to write expressions, you want the channels of your group nodes to have 0 values in translation and rotation, and 1 in scaling. If they are sitting right on top of the Rig and UpperBody nodes, this should be the case. Keep in mind that in versions of Maya before 4.5, you should not freeze the transforms of nodes that are parented in your skeleton hierarchy. Doing so changes the orientations of your skeleton centers and dislocates any IK handles that are child to these nodes. This problem seems to be fixed in the latest version of Maya, however. Making two group nodes as parents of the UpperBody icon creates extra channels that can be constrained in your expressions. After you have some channels to constrain on the UpBodAuto nodes, you can begin writing the expressions for averaging the torso between the leg box positions.
One important thing to check before writing the expressions is that the Feet node is directly between the leg boxes. Keep in mind that the information in the channels of the leg boxes is based on the parent node's position. You want, therefore, to make sure that the Feet node is directly between the leg boxes in X, and lined up with the center of the boxes in Z.
In addition, before writing the expressions, check the channels of the objects involved for any irregularities in the rotation or scaling channels. They should not, for instance, have Scaling values other than 1, or Rotation values other than 0. The first expression you write should constrain the X translation of the UpBodAuto1 node with an average. Adding a number of values, and dividing the result by the same number of values, creates an average.
Use the following syntax: (A + B) / 2 Replace the letters A and B in the preceding expression with each leg box's X translation to average the X translation of the UpBodAuto1 node. Do this on your rig by opening the Expression Editor, and type the following expression: UpBodAuto1.tx = (LtLeg.tx + RtLeg.tx) / 2; Name the expression Averages, and click Create. Test the control by translating one of the leg boxes in X. Your character's torso should remain directly in between both leg boxes. To constrain the Z translation in the same way, edit the expression by copying the first expression, and paste it on the next line, changing each X-axis to Z. The second line in your expression should look like this: UpBodAuto1.tz = (LtLeg.tz + RtLeg.tz) / 2; One other average constraint that you may want to use on your character is placed on the Y rotation channel.
Advanced Skeletal Maturation In Children
It is written like this: UpBodAuto1.ry = (LtLeg.ry + RtLeg.ry) / 2;. One thing you may notice when you test your average constraints is the leg boxes tend to pull the feet out of their sockets when a foot steps. The reason this happens is because the torso doesn't dip when your character steps in X or Z. In a real body, when you take a step, your torso dips.
The bigger you step, the more your torso dips. If your torso didn't dip, your feet would come out of your sockets too! So to make your character's torso automatically dip when your character takes a step, you can just create another expression. In the Expression Editor, click the New Expression button, and type in the following: UpBodAuto1.ty = 0 ((abs(LtLeg.tx - RtLeg.tx) + abs(LtLeg.tz - RtLeg.tz)) / 6); This expression finds how far the distance is between the feet by subtracting one foot from the other in X and Z. The absolute function removes negative signs from the expression, because there is no such thing as a negative distance. Dividing is needed because you don't want your character to dip as far as it steps. Name the expression Dip, click the Create button, and move your leg boxes to test the dip.
You probably need to divide the effect by more than 6 to produce less of a dip. In addition, your character has probably moved out of its default position in Y (see ).
This is because the expression is activated when the feet move apart, and the feet are already apart in their default pose. You can type in a number greater than 0 as the start number to adjust the character back up in Y. Another way you can make adjustments to your character's default position is by just translating your freedom nodes. The only channel that will be constrained on UpBodAuto2 is the X translation channel. So you can make any needed adjustments to the Z or Y translation of your character on this node. Also notice that although the expressions force the torso to move with the feet automatically, you can animate the UpperBody icon to compensate or add to the movement as needed. This enables you to animate basic movement of your character quickly, while adding subtle variations to the movement by manually animating the freedom node.
Advanced Skeleton Maya
Check to see whether the expressions constraining the torso caused your character to move out of its default position. Writing Conditional Expressions Another kind of advanced expression is a conditional expression, which uses the if and else commands. These commands enable you to set up a condition of some kind, and do one of two expressions depending on whether the condition evaluates as true or false. This is a good way, therefore, to have your character controls switch between two opposing actions. The automatic controls you create with conditional expressions on your character simulate the torso shifting weight when a foot is raised, and cause the hips to rotate in Y when a foot steps forward and backward.