RIGGING & ANIMATION BY XANTHE FARRUGIA
BLOG LINK:HTTP://RIGGINGANDANIMATION.TUMBLR.COM/
RIGGING AND ITS USES 3D rigging is the process of creating a skeleton for a 3D model so it can move properly. Characters are normally rigged before they are animated because if a character model isn’t rigged, than it cannot move around. After the modeler finishes building a character, it’s a static 3D mesh and before the 3D character has to be handed over to the team of animators, it must contain a system of joints and control handles so that the animators can pose the model.
A character rig is a digital skeleton combined to the 3D mesh. Exactly like a skeleton, a rig is made up of joints and bones, each containing a handle that the animators can then use to bend the character into a desired pose. A character rig can be either be simple or really complex. A basic rig for simple posing can be built into the 3D mesh in just a few hours, while a fully articulated rig might require days or weeks before the characters are ready for animation.
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Major components of Rigging
1. Placing the Skeleton – this is possibly the easiest part of the rigging process. Joints should be placed exactly where they would be in a real life skeleton. In order for the rig to work as it is supposed to, the bones and joints must follow a logical hierarchy. The first joint that is placed in a character is called the root joint. Every consequent joint has to be connected to the root either directly or indirectly through another joint.
2. Forward Kinematics - this is a method used to calculate the joint movement of a fully rigged character. When using this method, any given joint can affect parts of the skeleton that fall below it on the joint hierarchy. 3. Inverse Kinematics - this is the reverse process from forward kinematics, and is often used for rigging a character’s arms and legs. With this method, the terminating joint is directly placed by the animator, while the joints in the hierarchy that are placed above it are automatically interpolated by the software. 4. Constraints – the person who is doing the rigging, has to keep in mind that joints like the elbows and knees are limited to a single degree of freedom in the world and this means that they can only bend along one axis, and it is a good idea to set up joint constraints when you are building the rig. 5. Squash and Stretch - before the rigging is done, the person must consider whether the rig will support squash and stretch, or whether the character will move realistically. If you want to keep the animation realistic, it is really important to set a constraint to lock the position of each joint.
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ADVANCED RIGS
Advanced rigging is a type of rigging that uses controllers. Control rigs are equipped with inverse and forward kinematic tools that let the animator control the skeleton of a character easily and helps him to achieve great results over the entire body. Therefore control rigs helps to make complicated animation become easier.
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SKINNING
Skinning is the process of combining the 3D mesh to the joint setup created in the rigging process. It is the process pf taking the joints and bones of the rig and binding them to the actual 3D mesh. When the joints are bound to the 3D mesh it allows the animator to move the joints and the mesh will follow. The joints that were setup will now have effect on the vertices of the model and move them accordingly. The problem with this is that a rig normally consist of hundreds of individual joints, and most joints needs to have influence on only certain parts of the mesh. Hence this is where skinning is useful. Skinning is important not only for creating a model that moves as supposed to in all places, but also so it deforms properly. Skinning can be used to deform the model based on the transformation of one or more nodes. Usually when using skinning, invisible nodes that are called a skeleton or armature, are used to deform the model. Without skinning the mesh to the joints, the joints will have no influence on the actual 3D model.
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INVERSE AND FORWARD KINEMATICS Inverse Kinematics is the process of animating bones by going up the hierarchy which is great for keeping the hands in place while animating the upper body, while forward kinematics animate the bones by moving down the hierarchy, or forward which is great for smooth arcing movements.
Forward kinematics means that the character rig will follow the hierarchical chain. This means that there will be more control over the animator’s chain, but it also means that the animator has to position each joint in the chain independently of each other. Inverse Kinematics means that the child node in the rig’s hierarchy can influence the movement of its parents.
Forward Kinematics and Inverse Kinematics are really important to any animator. When Inverse Kinematics is used, a child within a character’s rig’s hierarchy can influence the movement of its parents. IK is great when you have a character that has to push against a wall, or keep their hand in one place, while the rest of the body is moving. When using forward Kinematics, the character rig follows the hierarchical chain. This means that you have more control over the chain, but it also means that you need to position each joint in the chain independently of each other. With FK if you positioned the character’s hand first, the rest of the arm wouldn’t follow along automatically because the chain moving up the arm would be upstream in the hierarchy. So the animator has to start by positioning the joint higher up in the hierarchy and then work his way down the hierarchy until he gets the desired pose. Therefore IK is great to be used when you need something to stay in its place, while FK can be used for everything else.
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PARENTING HIERARCHY PARENTING CAN BE USED BETWEEN LAYERS WITHIN A COMPOSITION TO SET UP A HIERARCHICAL LINKING STRUCTURE. IT IS THE TERM USED WHEN PLACING A NODE BENEATH ANOTHER IN A HIERARCHY SO THAT IT CAN BECOME THE CHILD OF THE NODE ABOVE IT IN THE HIERARCHY. THIS IS USED WHEN THE ANIMATOR WANTS A PART TO FOLLOW ANOTHER PART. THE ADVANTAGES OF PARENTING LAYERS IS THAT THE CHILD LAYERS WILL FOLLOW THE PARENT SMOOTHLY WITHOUT HAVING TO SELECT THEM OR TO CREATE A SERIES OF KEY FRAMES. THE DISADVANTAGE OF PARENTING LAYERS IS THAT THE ANIMATOR WOULDN’T BE ABLE TO MOVE THE PARENT INDEPENDENTLY OF ITS CHILDREN, SINCE THE CHILD LAYERS RECEIVE ALL THE TRANSFORMATION INFORMATION FROM THE PARENT. |
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RIGGING Head Neck02 Neck01
L_Clavicle
L_Shoulder
R_Clavicle R_Shoulder
Spine04 Spine03 Spine02 L_Elbow
R_Elbow
Spine01 Pelvis L_Hip
R_Hip
L_Wrist
R_Wrist
L_Hand R_Hand
R_Knee
L_Knee
L_Ankle R_Ankle R_Foot R_Toe
L_Foot L_Toe |
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MOTION CAPTURE
Motion Capture is a process used to record movements and later translates them onto a digital model. It records the actions of an actual human, and than uses the information to animate digital character models in 3D computer animation. The animation data is mapped onto a 3D model so that the model performs the same actions as the human. Motion Capture has a lot of purposes these days like tracking head movements of pilots, tracking the performance of athletes in sports, to determine injuries in medical applications, creating characters with real human movements in cartoons, games and films and loads of others.
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HISTORY OF MOTION CAPTURE
The use of motion capture is quite recent. It started in the 1970s and now it is beginning to spread. It wasn't recognized as revolutionary animation technique until the mid 1980's, when it was used for entertainment purposes. The idea of copying human motion has always been there. For example to make the human movements convincing, in the Disney movie "Snow White", they designed the animation with the reference of film, plays or real humans. this method was called rotoscoping. In fact motion capture was inspired by this technique.
Motion capture was originally used by the Military to track head movements of pilots by using electromagnetic motion capture.
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MECHANICAL MOTION CAPTURE This type of motion capture is used through the use of an exoskeleton. Each joint is connected to an angular encoder. The value of movement of each encoder is recorded by a computer that by knowing the position of the encoders can than copy these movements onto a model. The type of motion capture gives high precision and it has a great advantage that it is not influenced by other factors such as cameras. On the other hand it is limited by mechanical constraints related to the encoders and the exoskeleton The accuracy of this technique depends on the position of the encoders and the modelling of the skeleton.
MAGNETIC MOTION CAPTURE This technique of motion capture utilizes sensors placed on the body to capture the low-frequency magnetic field generated by a transmitter. the sensors are cabled to an electronic control unit that shows the locations withing the field. then the electronic control unit is connected to a computer that uses a software to represent the positions and rotations on a 3D model. The data captured by this technique is accurate and requires no further calculations. The only disadvantage that it has is that any metal object disturbs the magnetic field and distorts the data.
OPTICAL MOTION CAPTURE This technique is the the most commonly used. There exists two types of this technique which are 'Reflective' and 'Pulse LED'. Optical motion capture technique is capable of capturing data digitally, which is capable of turning real life motion into digital form. this technique brings better feeling of life to characters than the other techniques. Optical motion capture is done by using a number of special cameras from different angle. by using two or more camera angles, it brings a sense of a 3D world. It uses reflective markers which are placed on actor's body in order for the software to identify the position in the 3D world easily. The advantage of this type of motion capture is that the actors feel free to act and it is really detailed. The disadvantages are that it is very expensice, it is prone to light and markers can get hidden by props or other actors. |
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References 1http://3d.about.com/od/ Creating-3D-The-CGPipeline/a/What-IsRigging. htm 2 http://blog.digitaltutors. com/understandingskinning-vital-steprigging-project/ 3 https://github.com/libgd x/libgdx/wiki/3Danimations-andskinning 4 http://blog.digitaltutors. com/understandinginverse-and-forwardkinematics/ 5 https://www.video2brai n.com/en/lessons/usingparenting-to-createhierarchical-animation 6 https://www.toonboom. com/resources/tips-andtricks/rigging-animatedcharacters 7 http://download.autode sk.com/us/maya/2011h elp/index.html? url=./files/Inverse_kine matics_Parenting_a_mo del_into_a_skeleton_hie rarchy.htm,topicNumbe 8 r=d0e18213 https://courses.cs.washi ngton.edu/courses/cse4 58/08au/projects/projec 9 t6/rigSkel.html http://www.slideshare.n et/anveshranga/motioncapture-technology10 15980853 https://sagarlonkar.com/ about-2/motion/types-of11 capture motion-capture/ https://lukebeech.word press.com/motioncapture/ |
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