Date post: | 07-Nov-2014 |
Category: |
Documents |
Upload: | aannewball |
View: | 731 times |
Download: | 1 times |
Personajes digitalesAndrés Adolfo Navarro Newball
Personajes digitalesArticulation and animation of
digital creatures is informed by understanding of human and animal anatomy
Digital creatures can be realistic, fanciful, animal-based, or any combination thereof
Personajes digitalesTodas tienen anatomíaSus anatomías, realistas o no, se
basan en estructuras anatómicas de organismos existentes.
Deben funcionar de acuerdo a las leyes físicas de su propio entorno
Personajes digitalesPersonajes realistas se benefician
de los organismos que buscan imitar
Personajes nuevos. Pueden ser diseccionados en componentes basadas en organismos reales
Personajes digitalesLa clave es la estructura anatómica
básica Analogía evolutiva entre las
estructuras que dan movimiento
Young Sherlock Holmes, Caballero del vitral, 1985http://www.youtube.com/watch?v=CT-qV41ovv4
http://www.youtube.com/watch?v=v_FfHA5whXc
FormaRestringida por el ambiente
◦ Terrestre / acuático◦ Dieta◦ Velocidad de movimiento
Piel◦ Skin of a biological creature cannot hold
its form without the underlying anatomy◦ The skin of a digital creature exists
without need for support from underlying structures.
Forma The form of a biological creature is determined by the
expression of those underlying structures through the skin.
It is important to understand how the form of the digital creature could conceivably be built up from the inside
The responsibility for identifying anatomical elements falls primarily to the artists tasked with creating the animation rigging and deformation systems for the creatures. Saphira, Eragon
http://www.youtube.com/watch?v=bpkwhr5P0l4
Forma Bulge: fat, organ, muscle, cartilage, or
bone◦ If bone: connection point for articulations?◦ If muscle: relaxed or contracted?
Ridges:◦ Convex curvature of bulges
Bulges and ridges communicate the existence of anatomical elements under the skin.
Cavities and creases the absence of support for the skin. Areas of great articulation
Forma
Preferible modelar en una pose neutral
Articulación Rigging:
Construir el sistema musculo-esqueletal de un personaje
Tomar un modelo inanimado y transformarlo en un personaje que el animador puede manipular cuadro a cuadro para crear movimiento
Ensamble de una estructura de soporte. Soporte requerido mas para articulación que estructural
Determina numero y posición de puntos de articulación
Luego, se relacionan los puntos de articulación a la piel
Articulación Músculos orientan movimiento
del sistema esqueletal… Pero los esqueletos limitan los
rangos de movimientoEj: The Atlas-Axis Joint of the
Upper Neck Head◦Separación del movimiento “si” y
“no”
Articulación En estos “huesos” digitales el
movimiento es realizado con translaciones y rotaciones.
Pueden ser movidos rotados, escalados en el espacio
Pueden conectarseBásicamente constan de un pivote y
una longitud. Conectados al end point de su padre.
Desconectado de otros objetos, no sirve de mucho
Articulación
Jar Jar Bink’shttp://www.youtube.com/watch?v=5C9JX6VRjn0
Articulación Biological accuracy to the number of bones
is necessary only if photorealistic representation of an actual skeleton is required
The effect of individual bones in a biological system on the articulation and deformations of skin is mitigated by the action of other parts of the system
Articulación Accuracy in the location of pivot points, the
way the bones behave relative to one another in the deformation of surfaces is more important than the number of bones for digital creatures
There are various techniques that can be employed digitally to replicate the volume preserving function of the rib cage and digestive organs, but often the more efficient solution is to simply deviate from the biological placement of the spine joints
Sistema de controlManera como la intención se
convierte en acción Key frame Captura de movimiento Procedimental
ConexiónMantiene las partes del sistema
juntas.◦ Directa: jerarquía padre – hijo
El movimiento del padre orienta la posición del hijo Estructuras anatómicas mas complejas requieren
mayor estudio
◦ No jerárquica: Permite orientar el movimiento de un hueso gracias
a agentes externos Reduce problemas relacionados con cálculos
◦ Variable: Relación matemática entre objetos Crea comportamientos dinámicos
Creaturas sin huesoAltamente deformablesLos puntos de articulación se
mueven constantemente uno respecto al otro
Se pone una columna y conexiones variables
MovimientoPueden responder a las
siguientes leyes:◦Físicas◦Estructura / morfología◦Funcionalidad de la estructura◦EJ:
http://www.youtube.com/watch?v=N64KOQkbyiI http://www.youtube.com/watch?v=mYHK3wL11
eI&feature=related
Medio en que se mueve el organismo
Movimiento
Movimiento Visible motion that appears internally motivated
or the result of internally motivated action. However, the initiation of the action for a digital creature is external, puppeted
Barriers to motion can also be created but they are computationally expensive if applied as collision detections. More often limitations are programmed into the rig
Driving points in digital creatures are locations where several appendages join together. Controlling a driving point moves the origin points of appendages as a group
Movimiento Physically driven actions for digital creatures
typically exist as layers of motion applied on top of the primary action
Forward kinematic systems describe each joint’s position as solely derivative of it’s parent’s action. In a forward kinematic system the rotation of a parent joint drives the position of the child
An inverse kinematic system describes each joint’s position relative to the action of the last joint in the chain. In inverse kinematic systems the joints between the root and the end joint must solve their positions using the first and last joints as guides
MovimientoDynamic posing differs significantly from IK
and FK techniques. It consists of a non-hierarchical arrangement of articulation points and a dynamic solver that determines how those points relate to one another
The typical role for digital muscles is to act as secondary deformers of the skin during motion.
Hollow man, 2000http://www.youtube.com/watch?v=BMHsrGA061o
MovimientoDeformación: creation of a digital
analog to the effect of bones and muscles moving skin◦Enveloping◦Skinning
Caso 1, el gato con botasEl mejor papel de Antonio
Banderas a la fechahttp://www.youtube.com/watch?v
=7LbumSMoQK8
El gato con botas
El gato con botas
Character setup includes: joint articulation and limb motion, facial animation (simulated muscles, jaw
movement, skin stretching), body deformations to represent muscle
and skin behavior, hair and fur motion, the hierarchy of body part relationships, special character props such as Puss’
animated hat.
El gato con botasDevelopment
◦Involves designing the technical solutions needed to help realize the Director’s creative vision for the project
Design and implementation of the rigging systems
Ongoing Support of the animation rigs for Character Animators once Production begins.
El gato con botasPuss-In-Boots: One
Complicated Cat
El gato con botasUltimately, the rig of Puss-In-
Boots involved designing, building, testing, refining, and supporting a complex motion system. For Puss-In-Boots, the motion system was extremely complex and involved a large number of individual components far beyond anything that was constructed for Shrek
El gato con botas
El gato con botas If, for example, a character needs to be able
to achieve certain actions, then a rig must be constructed that enables the character with those capabilities. In this case, what started out as a cat eventually required the ability to also stand up and walk on its two hind legs just like a human.
Part of the work involved setting up multiple sets of joints—joints that worked differently depending on the situation he was in (whether he was in cat mode or human mode).
El gato con botasPivote en modo gato
Balance:dedos largos pero no tanto
El gato con botas The height of the boots on the inside-back
of Puss’ legs, maintaining the original height on the outside-front. This way, the boots appear to ride high but do not require lots of necessary collision detection
The first model of Puss-In-Boots started out as a real cat (a tabby). But in order to achieve recognizable human facial expressions, his face was slowly pushed towards being more human.
El gato con botas
El gato con botasAlthough the feather strands were
added by the FX department, the spine of the feather became fully animatable as well
To accompany Puss’ boots, Puss also dons a wide, brown leather belt. The belt can be animated so it slides over his body interacting in a believable way with the fur
El gato con botasThe functions of the Character TD department
include:◦ Ensure character designs are functional and
aesthetically match the Director’s vision,◦ Define character setup standards,◦ Develop character setup technology,◦ Implement and integrate the character setup system
(motion system, facial animation, body deformations, tight clothing/wrinkles, whiskers/hair setup plus dynamics, character props setup plus dynamics
◦ Set up characters for animation, and◦ Support characters throughout all phases of
production for the Character Animation and Lighting departments
Caso 2, Los lobos alfa
Los lobos alfaThe system allows the user to have
high-level control over the actions of a character, while the emotional state of the character is autonomously maintained by the computer
Each pup forms a social relationship with the other; the next time they meet, their remembered relationships will affect the way in which they interact
Los lobos alfaEach wolf maintains an emotional state
that is affected by its interactions with the world. A wolf is able to perceive the identity of its pack mates, recognizing them as distinct individuals. It forms an emotional memory of each individual after its first interaction with it
It was necessary to choose a computational representation that captures the necessary range of emotional phenomena
Los lobos alfa
SkinningLa piel se debe mover y deformar junto
con el esqueletoBrinda correspondencia entre piel y
esqueleto a través de una serie de pesosDefine el movimiento de la piel como
una función del esqueleto Asociar una malla al esqueletoAlgunos métodos:
Skeletal Subspace Deformation: poco flexible Animation Space: el mejor Multi-Weight Enveloping: overfitting
Skinningv: posición de un vértice : posición de reposo de v 1 ... b: huesosTi = matriz de transformación del
i – esimo hueso = Ti en reposo
v̂
iT̂
SkinningConvertir la posición del i - esimo
vértice en reposo de coordenadas del modelo a coordenadas del hueso
SkinningConvertir el vértice en
coordenadas de hueso a coordenadas del modelo
Skeletal Subspace DeformationOtros nombres:
Linear Blend Skinning, Enveloping and Vertex Blending
Determines the new position of a vertex by linearly combining the results of the vertex transformed rigidly with each bone
Skeletal Subspace DeformationA scalar weight, wi, is given to
each influencing bone and the weighted sum gives the vertex’s position
Animation spaceProvides greater flexibility than SSD
by changing the single rest pose position of each vertex
Allows each component of the vertex’s position to be influenced independently by each bone
Multi-Weight Enveloping
These additional weights allow each component of v to be influenced, independently of one another, in each component of a bone’s movement.
Bibliografía The Morphology of Digital Creatures Tim McLaughlin, Stuart S. Sumida
Ph.D. Art-Directed Technology: Anatomy of a Shrek2 Sequence
SIGGRAPH 2004 Course. Rachel Falk, Denise Minter, Conrad Vernon, Guillaume Aretos, Lucia Modesto, Arnauld Lamorlette, Nick Walker, Tim Cheung, Janet Rentel-Lavin, Harry Max
Leashing the AlphaWolves: Mixing User Direction with Autonomous Emotion in a Pack of Semi-Autonomous Virtual Characters. Bill Tomlinson, Marc Downie, Matt Berlin, Jesse Gray, Derek Lyons, Jennie Cochran, and Bruce Blumberg Synthetic Characters Group, The Media Lab, MIT
A Comparison of Linear Skinning Techniques for Character Animation. David Jacka, Ashley Reid, Bruce Merry, James Gain, University of Cape Town
Autonomous Animation and Control of Four-Legged Animals. Evangelos Kokkevis, Dimitri Metaxas and Norman I. Badler
The 3D Skeleton Pruning for Removing Undesired Joints. Porawat VISUTSAK, Korakot PRACHUMRAK
Skinning Mesh Animations. Doug L. James Christopher D. Twigg