How to create a bone diagram?

Transcription

1 How to create a bone diagram? This tutorial shows how to create a bone diagram. A bone diagram represents relations between endpoints and surface interaction. A bone is transformed by a force field, and the skin transforms with the bone according to its settings. It can be usefull for creating diagrams that interact with for example a ground plane or planes that are transformed into a design. It covers the basics of fields kinetics and skin. 1. Create the bones. Fisrt we need to create the bones and make them interact with a force field, the forcefield represents an environmental constant. We want each end joint to interact with a different force (for example a different program aspect) To create the bones we need to set them up carefully, it is wise in this case to use the Snap Grid. We'll create 3 individual bones and connect these lateron using the hypergraph. First create a bone (Animation Menuset >> Skeleton >> Joint) Lets draw a bone in the TOP view. Select three coordinates (snap to the grid) and press enter to end the joint

2 duplicate this joint 2x and place them as in the picture above. We want the bones to have a small initial bend so select the second joint of each bone and change its Y coordinate. Bring the 3 joint of each bone back to the ground plane by setting its Y coordinate back to 0

3 2. Create the IK handles we want the bones to react as some sort of kinetic. This means we have to create in invers kinetic handle, the IK two bone handle is for posing joint chains that consist of three joints (two bones). The IK two bone handle is ideal for posing joint chains that you would like to stay in more or less the same plane, even though that plane can rotate. For example, the shoulder, elbow, and wrist joints of an arm all stay within the same plane. for further understand of the two bone IK handle look at the Maya Manual to create the IK handle for one of the bones select from the Animation Menuset >> Skeleton >> IK Handle Tool. Then Select the first joint of the bone and then select the last one.

4 When you move the IKHandle you'll notice that the bone reacts as a human arm. Do the same for al the other bones. 3. The Pole vector When moving bones it sometimes happens that the bones switch direction or move in a strange way. This happens when the IK Handle approaches the Pole vector or alligns with it. To be sure that The pole vector doesn't mess up your scene you can place it in the correct direction. (select the IKHandle >> select the manipulator tool >> move the Pole manipulator in the correct direction (as shown in the image).

5 do the same for the other three bones. 4. Constrain a Active Rigid body to the IKHandle We want the IK handle to move/animate with certain force field. But we can not attach a field to the IK handle of the bone, therefore we have to attach the handle to a active rigid body. We can do this in two ways, parenting or constraining. Here I'll show you how to constrain two objects. First create a nurbsphere scale (0.2,0.2,0,2) To constrain the two >> first select the sphere >> and shift select the ik handle and select from the Dynamic Menuset >> Constrain >> Point Constrain. You'll notice that the IK handle snaps to the sphere, move the sphere back to the IK handles original position.

6 Do the same for all the other bones. 6. Attach Fields. We want the IKhandles to move, and now that they are connected to the spheres we can by dynamic moving the spheres. To attach a newton field to the sphere >> select sphere >> Dynamic menuset >> Field >> Newton. Move the Newton Field close to the ball and play the animation. If everything went well, create the Spheres and the newton fields for all the other joints.

7 7. Connect the joints We want the whole joint system to work as one piece to manipulate a surface, therefore we have to connect the bones to each other. You can do this with the hypergraph (Windw >> Hypergraph). The hypergraph is one of two main scene management editors in Maya (the other is the outliner). The hypergraph shows a network of boxes representing nodes and lines connecting them representing relationships. You can use the hypergraph to view and edit hierarchical relationships (the same information the outliner shows) or dependency relationships (input and output connections between attributes). To connect the second bone to the first bone we need to MMD the second bone on the first joint of bone number 1. The result should be like in the picture below

8 do the same thing with the third bone and drop it on the second bone. (see picture below)

9 If place the force field in a line with the bones nothing special will probably happen, but when you place the first newton field outside the line of the first bone, thing are getting more interested. 8. Add the skin/suface. Stop the animation and rewind the movie The final step is to create the surface that is going to be manipulated. Create a Nurbs plane and set the C and V patches to10 (Modeling menuset >> Create >> Nurbs >> Plane optionbox). Spread the plan over the joints (see picture)

10 To connect the plane to the bones you'll have to select the plane, and select the joint that you want to connect to the plane, in our case joint1. Then select from the Dynamic Menuset >> Skin >> Smooth Bind optinbox. Hhere you can change some settings. Bind to: Specifies whether to bind to an entire skeleton or only to selected joints. Selections include Complete Skeleton or Selected Joints. Bind Method: Specifies whether joints will influence nearby skin points based on the skeleton's hierarchy, or only on joint proximity to skin points. Selections include Closest Joint or Closest Distance. Max Influences: Specifies the number of joints that can influence each skin point. Default is 5. (You can also limit the range of joint influence by specifying the Dropoff Rate.) Dropoff Rate: Specifies how rapidly the influence of each joint on skin points will decrease with the distance from each joint (and the joint's bone). The greater the Dropoff Rate, the more rapid the decrease in influence with distance. The lower the Dropoff Rate, the further the influence of each joint. When you bind skin, the Dropoff Rate applies to all the selected joints. Use the slider to specify values between 0.1 and 10. You can enter values up to 100. We'll leave these setting to their default value for now. Select Bind skin. If everything wen well you are able to play your animation with a skin deformation.

11 9.Enrich the diagram. If everything went well you can put extra object in your scene create more nodes create different forces create more IK handles