Automatic adjustment of rigs to extracted skeletons

In the animation, the process of rigging a character is an elaborated and time consuming task. The rig is developed for a specific character, and it can not be reused in other meshes. In this paper we present a method to automatically adjust a human-like character rig to an arbitrary human-like 3D mesh, using a extracted skeleton obtained from the input mesh. Our method is based on the selection and extraction of feature points, to find an equivalence between an extracted skeleton and the animation rig.Peer ReviewedPostprint (published version

Improving automatic rigging for 3D humanoid characters

In the field of computer animation the process of creating an animated character is usually a long and tedious task. An animation character is usually efined by a 3D mesh (a set of triangles in the space) that gives its external appearance or shape to the character. It also used to have an inner structure, the skeleton. When a skeleton is associated to a character mesh, this association is called skeleton binding, and a skeleton bound to a character mesh is an animation rig. Rigging from scratch a character can be a very boring process. The definition and creation of a centered skeleton together with the ’painting’, by an artist,of the influence parameters between the skeleton and the mesh (the skinning) s the most demanding part to achieve an acceptable behavior for a character. This rigging process can be simplified and accelerated using an automatic rigging method. Automatic rigging methods consist in taking as input a 3D mesh, generate a skeleton based in the shape of the original model, bound the input mesh to the generated skeleton, and finally to compute a set of parameters based in a chosen skinning method. The main objective of this thesis is to generate a method for rigging a 3D arbitrary model with minimum user interaction. This can be useful to people without experience in the animation field or to experienced people to accelerate the rigging process from days to hours or minutes depending the needed quality. Having in mind this situation we have designed our method as a set of tools that can be applied to general input models defined by an artist. The contributions made in the development of this thesis can be summarized as: • Generation of an animation Rig: Having an arbitrary closed mesh we have implemented a thinning method to create first an unrefined geometry skeleton that captures the topology and pose of the input character. Using this geometric skeleton as starting point we use a refining method that creates an adjusted logic skeleton based in a template, or may be defined by the user, that is compatible with the current animation formats. The output logic skeleton is specific for each character, and it is bounded to the input mesh to create an animation rig. • Skinning: Having defined an animation rig for an arbitrary mesh we have developed an improved skinning method; this method is based on the Linear Blend Skinning(LBS) algorithm. Our contributions in the skinning field can be sub-divided in: – We propose a segmentation method that works as the core element in a weight assigning algorithm and a skinning lgorithm, we also have developed an automatic algorithm to compute the skin weights of the LBS Skinning of a rigged polygonal mesh. – Our proposed skinning algorithm uses as base the features of the LBS Skinning. The main purpose of the developed algorithm is to solve the well-known ”candy wrap” artifact; that produces a substantial loss of volume when a link of an animation skeleton is rotated over its own axis. We have compared our results with the most important methods in the skinning field, such as Dual Quaternion Skinning (DQS) and LBS, achieving a better performance over DQS and an improvement in quality over LBS. • Animation tools: We have developed a set of Autodesk Maya commands that works together as rig tool, using our previous proposed methods. • Animation loader: Moreover, an animation loader tool has been implemented, that allows the user to load animations from a skeleton with different structure to a rigged 3D model. The contributions previously described has been published in 3 research papers, the first two were presented in international congresses and the third one was acepted for its publication in an JCR indexed journal.En el campo de la animación por computadora el proceso de crear un personaje de animación es comúnmente una tarea larga y tediosa. Un personaje de animación está definido usualmente por una malla tridimensional (un conjunto de triángulos en el espacio) que le dan su apariencia externa y forma al personaje. Es igualmente común que este tenga una estructura interna, un esqueleto de animación. Cuando un esqueleto esta asociado con una malla tridimensional, a esta asociación se le llama ligado de esqueleto, y un esqueleto ligado a la mallade un personaje es conocido en inglés como "animation rig" (el conjunto de elementos necesarios, que unidos sirven para animar un personaje). Hacer el rigging desde cero de un personaje puede ser un proceso muy tedioso. La definición y creación de un esqueleto centrado en la malla junto con el "pintado" por medio de un artista de los parámetros de influencia entre el esqueleto y la malla 3D (lo que se conoce como skinning) es la parte mas demandante para alcanzar un compartimiento aceptable al deformase (moverse) la malla de un personaje. Los métodos de rigging automáticos consisten en tomar una malla tridimensional como elemento de entrada, generar un esqueleto basado en la forma del modelo original, ligar la malla de entrada al esqueleto generado y finamente calcular el conjunto de parámetros utilizados por el método de skinning elegido. El principal objetivo de esta tesis es el generar un método de rigging para un modelo tridimensional arbitrario con una interacción mínima del usuario. Este método puede ser útil para gente con poca experiencia en el campo de la animación, o para gente experimentada que quiera acelerar el proceso de rigging de días a horas o inclusive minutos, dependiendo de la calidad requerida. Teniendo en mente esta situación, hemos diseñado nuestro método como un conjunto de herramientas las cuales pueden ser aplicadas a modelos de entrada generados por cualquier artista. Las contribuciones hechas en el desarrollo de esta tesis pueden resumirse a: -Generación de un rig de animación: Teniendo una malla cerrada cualquiera, hemos implementado un método para crear primero un esqueleto geométrico sin refinar, el cual capture la pose y la topología del personaje usado como elemento de entrada. Tomando este esqueleto geométrico como punto de partida usamos un método de refinado que crea un "esqueleto lógico" adaptado a la forma del geométrico basándonos en una plantilla definida por el usuario o previamente definida, que sea compatible con los formatos actuales de animación. El esqueleto lógico generado será especifico para cada personaje, y esta ligado a la malla de entrada para así crear un rig de animación. - Skinning: Teniendo definido un rig de animación para una malla de entrada arbitraria, hemos desarrollado un método mejorado de skinning, este método sera basado en el algoritmo "Linear Blending Skinnig" (algoritmo de skinning por combinación lineal, LBS por sus siglas en inglés). Nuestras contribuciones en el campo del skinnig son: - Proponemos un nuevo método de segmentación de mallas que sea la parte medular para algoritmos de asignación automática de pesos y de skinning, también hemos desarrollado un algoritmo automático que calcule los pesos utilizados por el algoritmo LBS para una malla poligonal que tenga un rig de animación. - Nuestro algoritmo de skinning propuesto usará como base las características del algoritmo LBS. El principal propósito del algoritmo desarrollado es el solucionar el defecto conocido como "envoltura de caramelo" (candy wrapper artifact), que produce una substancial perdida de volumen al rotar una de las articulaciones del esqueleto de animación sobre su propio eje. Nuestros resultados son comparados con los métodos mas importantes en el campo del skinning tal como Cuaterniones Duales (Dual Quaternions Skinning, DQS) y LBS, alcanzando un mejor desempeño que DQS y una mejora importante sobre LBSPostprint (published version

Analysis of Design Principles and Requirements for Procedural Rigging of Bipeds and Quadrupeds Characters with Custom Manipulators for Animation

Character rigging is a process of endowing a character with a set of custom manipulators and controls making it easy to animate by the animators. These controls consist of simple joints, handles, or even separate character selection windows.This research paper present an automated rigging system for quadruped characters with custom controls and manipulators for animation.The full character rigging mechanism is procedurally driven based on various principles and requirements used by the riggers and animators. The automation is achieved initially by creating widgets according to the character type. These widgets then can be customized by the rigger according to the character shape, height and proportion. Then joint locations for each body parts are calculated and widgets are replaced programmatically.Finally a complete and fully operational procedurally generated character control rig is created and attached with the underlying skeletal joints. The functionality and feasibility of the rig was analyzed from various source of actual character motion and a requirements criterion was met. The final rigged character provides an efficient and easy to manipulate control rig with no lagging and at high frame rate.Comment: 21 pages, 24 figures, 4 Algorithms, Journal Pape

Animation de personnages 3D par le sketching 2D

Free-form animation allows for exaggerated and artistic styles of motions such as stretching character limbs and animating imaginary creatures such as dragons. Creating these animations requires tools flexible enough to shape characters into arbitrary poses, and control motion at any instant in time. The current approach to free-form animation is keyframing: a manual task in which animators deform characters at individual instants in time by clicking-and-dragging individual body parts one at a time. While this approach is flexible, it is challenging to create quality animations that follow high-level artistic principles---as keyframing tools only provide localized control both spatially and temporally. When drawing poses and motions, artists rely on different sketch-based abstractions that help fulfill high-level aesthetic and artistic principles. For instance, animators will draw textit{lines of action} to create more readable and textit{expressive} poses. To coordinate movements, animators will sketch textit{motion abstractions} such as semi-circles and loops to coordinate a bouncing and rolling motions. Unfortunately, these drawing tools are not part of the free-form animation tool set today. The fact that we cannot use the same artistic tools for drawing when animating 3D characters has an important consequence: 3D animation tools are not involved in the creative process. Instead, animators create by first drawing on paper, and only later are 3D animation tools used to fulfill the pose or animation. The reason we do not have these artistic tools (the line of action, and motion abstractions) in the current animation tool set is because we lack a formal understanding relating the character's shape---possible over time---to the drawn abstraction's shape. Hence the main contribution of this thesis is a formal understanding of pose and motion abstractions (line of action and motion abstractions) together with a set of algorithms that allow using these tools in a free-form setting. As a result, the techniques described in this thesis allow exaggerated poses and movements that may include squash and stretch, and can be used with various character morphologies. These pose and animation drafting tools can be extended. For instance, an animator can sketch and compose different layers of motion on top of one another, add twist around strokes, or turning the strokes into elastic ribbons. The main contributions of this thesis are summarized as follows: -The line of action facilitating expressive posing by directly sketching the overall flow of the character's pose. -The space-time curve allowing to draft full coordinated movements with a single stroke---applicable to arbitrary characters. -A fast and robust skeletal line matching algorithm that supports squash-and-stretch. -Elastic lines of action with dynamically constrained bones for driving the motion of a multi-legged character with a single moving 2D line.L'animation expressive permet des styles de mouvements exagerés et artistiques comme l'étirement de parties du corps ou encore l'animation de créatures imaginaires comme un dragon. Créer ce genre d'animation nécessite des outils assez flexible afin de déformer les personnages en des poses quelconques, ainsi que de pouvoir contrôler l'animation à tout moment dans le temps. L'approche acutelle pour l'animation expressive est le keyframing: une approche manuelle avec laquelle les animateurs déforment leur personnage un moment spécifique dans le temps en cliquand et glissant la souris sur une partis spécifique du corps---un à la fois. Malgré le fait que cette approche soit flexible, il est difficile de créer des animations de qualité qui suivent les principes artistiques, puisque le keyframing permet seulement qu'un contrôle local spatiallement et temporellement. Lorsqu'ils dessinent des poses ou des mouvements, les artistes s'appuient sur différentes abstractions sous forme de croquis qui facillitent la réalisation de certain principes artistiques. Par example, certains animateurs dessinent des lignes d'action afin de créer une pose plus lisible et expressive. Afin de coordonner un mouvement, les animateurs vont souvent dessiner des abstractions de mouvement comme des demi-cercles pour des sauts, ou des boucles pour des pirouettes---leur permettant de pratiquer la coordination du mouvement. Malheureusement, ces outils artistiques ne font pas partis de l'ensemble d'outils de keyframing actuelle. Le fait que l'on ne puisse pas employer les même outils artistiques pour animater des personnages 3D a une forte conséquence: les outils d'animation 3D ne sont pas employés dans le processus créatif. Aujourd'hui, les animateurs créent sur du papier et utilisent le keyframing seulement à la fin pour réaliser leur animation. La raison pour laquelle nous n'avons pas ces outils artistiques (ligne d'action, abstractions de mouvement) en animation 3D, est parce qu'il manque une compréhension formelle de ceux-ci qui nous permettrais d'exprimer la forme du personnage---potentiellement au cours du temps---en fonction de la forme de ces croquis. Ainsi la contribution principale de cette thèse est une compréhension formelle et mathématique des abstractions de forme et de mouvement courrament employées par des artistes, ainsi qu'un ensemble d'algorithme qui permet l'utilisation de ces outils artistiques pour créer des animations expressives. C'est-à-dire que les outils développés dans cette thèse permettent d'étirer des parties du corps ainsi que d'animer des personnages de différentes morphologies. J'introduis aussi plusieurs extentions à ces outils. Par example, j'explore l'idée de sculpter du mouvement en permettant à l'artiste de dessigner plusieurs couches de mouvement une par dessus l'autre, de twister en 3D les croquis, ou encore d'animer un croquis ligne comme un élastique. Les contributions principales de cette thèse, aussi résumé ci-dessous: -La ligne d'action facilitant la création de poses expressives en dessinant directement le flow complet du personnage. -La courbe spatio-temporelle qui permet de spécifier un mouvement coordoné complet avec un seul geste (en dessinant une seule courbe), applicable à n'importe quel personnage 3D. -Un algorithme de matching rapide et robuste qui permet du ``squash and stretch''. -La ligne d'action élastique avec des attachements dynamiques à la ligne permettant d'animer un personnages à plusieurs jambes (bras) avec une seule ligne 2D animée

Animation de personnages 3D par le sketching 2D

Free-form animation allows for exaggerated and artistic styles of motions such as stretching character limbs and animating imaginary creatures such as dragons. Creating these animations requires tools flexible enough to shape characters into arbitrary poses, and control motion at any instant in time. The current approach to free-form animation is keyframing: a manual task in which animators deform characters at individual instants in time by clicking-and-dragging individual body parts one at a time. While this approach is flexible, it is challenging to create quality animations that follow high-level artistic principles---as keyframing tools only provide localized control both spatially and temporally. When drawing poses and motions, artists rely on different sketch-based abstractions that help fulfill high-level aesthetic and artistic principles. For instance, animators will draw textit{lines of action} to create more readable and textit{expressive} poses. To coordinate movements, animators will sketch textit{motion abstractions} such as semi-circles and loops to coordinate a bouncing and rolling motions. Unfortunately, these drawing tools are not part of the free-form animation tool set today. The fact that we cannot use the same artistic tools for drawing when animating 3D characters has an important consequence: 3D animation tools are not involved in the creative process. Instead, animators create by first drawing on paper, and only later are 3D animation tools used to fulfill the pose or animation. The reason we do not have these artistic tools (the line of action, and motion abstractions) in the current animation tool set is because we lack a formal understanding relating the character's shape---possible over time---to the drawn abstraction's shape. Hence the main contribution of this thesis is a formal understanding of pose and motion abstractions (line of action and motion abstractions) together with a set of algorithms that allow using these tools in a free-form setting. As a result, the techniques described in this thesis allow exaggerated poses and movements that may include squash and stretch, and can be used with various character morphologies. These pose and animation drafting tools can be extended. For instance, an animator can sketch and compose different layers of motion on top of one another, add twist around strokes, or turning the strokes into elastic ribbons. The main contributions of this thesis are summarized as follows: -The line of action facilitating expressive posing by directly sketching the overall flow of the character's pose. -The space-time curve allowing to draft full coordinated movements with a single stroke---applicable to arbitrary characters. -A fast and robust skeletal line matching algorithm that supports squash-and-stretch. -Elastic lines of action with dynamically constrained bones for driving the motion of a multi-legged character with a single moving 2D line.L'animation expressive permet des styles de mouvements exagerés et artistiques comme l'étirement de parties du corps ou encore l'animation de créatures imaginaires comme un dragon. Créer ce genre d'animation nécessite des outils assez flexible afin de déformer les personnages en des poses quelconques, ainsi que de pouvoir contrôler l'animation à tout moment dans le temps. L'approche acutelle pour l'animation expressive est le keyframing: une approche manuelle avec laquelle les animateurs déforment leur personnage un moment spécifique dans le temps en cliquand et glissant la souris sur une partis spécifique du corps---un à la fois. Malgré le fait que cette approche soit flexible, il est difficile de créer des animations de qualité qui suivent les principes artistiques, puisque le keyframing permet seulement qu'un contrôle local spatiallement et temporellement. Lorsqu'ils dessinent des poses ou des mouvements, les artistes s'appuient sur différentes abstractions sous forme de croquis qui facillitent la réalisation de certain principes artistiques. Par example, certains animateurs dessinent des lignes d'action afin de créer une pose plus lisible et expressive. Afin de coordonner un mouvement, les animateurs vont souvent dessiner des abstractions de mouvement comme des demi-cercles pour des sauts, ou des boucles pour des pirouettes---leur permettant de pratiquer la coordination du mouvement. Malheureusement, ces outils artistiques ne font pas partis de l'ensemble d'outils de keyframing actuelle. Le fait que l'on ne puisse pas employer les même outils artistiques pour animater des personnages 3D a une forte conséquence: les outils d'animation 3D ne sont pas employés dans le processus créatif. Aujourd'hui, les animateurs créent sur du papier et utilisent le keyframing seulement à la fin pour réaliser leur animation. La raison pour laquelle nous n'avons pas ces outils artistiques (ligne d'action, abstractions de mouvement) en animation 3D, est parce qu'il manque une compréhension formelle de ceux-ci qui nous permettrais d'exprimer la forme du personnage---potentiellement au cours du temps---en fonction de la forme de ces croquis. Ainsi la contribution principale de cette thèse est une compréhension formelle et mathématique des abstractions de forme et de mouvement courrament employées par des artistes, ainsi qu'un ensemble d'algorithme qui permet l'utilisation de ces outils artistiques pour créer des animations expressives. C'est-à-dire que les outils développés dans cette thèse permettent d'étirer des parties du corps ainsi que d'animer des personnages de différentes morphologies. J'introduis aussi plusieurs extentions à ces outils. Par example, j'explore l'idée de sculpter du mouvement en permettant à l'artiste de dessigner plusieurs couches de mouvement une par dessus l'autre, de twister en 3D les croquis, ou encore d'animer un croquis ligne comme un élastique. Les contributions principales de cette thèse, aussi résumé ci-dessous: -La ligne d'action facilitant la création de poses expressives en dessinant directement le flow complet du personnage. -La courbe spatio-temporelle qui permet de spécifier un mouvement coordoné complet avec un seul geste (en dessinant une seule courbe), applicable à n'importe quel personnage 3D. -Un algorithme de matching rapide et robuste qui permet du ``squash and stretch''. -La ligne d'action élastique avec des attachements dynamiques à la ligne permettant d'animer un personnages à plusieurs jambes (bras) avec une seule ligne 2D animée

Investigation of advanced navigation and guidance system concepts for all-weather rotorcraft operations

Results are presented of a survey conducted of active helicopter operators to determine the extent to which they wish to operate in IMC conditions, the visibility limits under which they would operate, the revenue benefits to be gained, and the percent of aircraft cost they would pay for such increased capability. Candidate systems were examined for capability to meet the requirements of a mission model constructed to represent the modes of flight normally encountered in low visibility conditions. Recommendations are made for development of high resolution radar, simulation of the control display system for steep approaches, and for development of an obstacle sensing system for detecting wires. A cost feasibility analysis is included

Ecological and environmental controls on the fine-scale distribution of cold-water corals in the North-East Atlantic

This thesis integrated acoustic, high-definition video and hydrodynamic data to study the distribution, morphology and ecology of cold-water corals (CWC) in the Mingulay Reef area (Chapter 2), the Tisler Reef area (Chapter 3) and the Logachev Mound area (Chapter 4). A new British Geological Survey (BGS) ArcGIS seabed mapping toolbox was developed and quantified semi-automatically the morphometric and acoustic characteristics of CWC reefs. Over 500 Lophelia pertusa reef mounds were delineated and characterised at the Mingulay Reef Complex (Chapter 2), 14 at the Tisler Reef (Norway) (Chapter 3) and 123 in the Logachev Area (Chapter 4). These reefs all had large amounts of small round-shaped mounds. Additionally, the Logachev area had very large dendriform-shaped mounds. A microbathymetric grid of the central area of the Mingulay Reef was used to identify individual live coral colonies (1-7 m) that provided data to predict the likelihood of presence of live coral colonies on biogenic reef mounds (Chapter 2). The distribution and morphology of L. pertusa colonies and the sponges Mycale lingua and Geodia sp. within the Tisler Reef, revealed the importance of local hydrodynamics and substrate availability (Chapter 3). Non-scleractinian corals associated with the Logachev mounds (Chapter 4) proved to be abundant, biodiverse and function as a habitat for associated organisms. Differences in their distribution were found to be related to food supply, the availability and stability of settling substrates. This thesis showed that the BGS Seabed Mapping Toolbox is useful to study the ecology and morphology of reef mounds within and between reefs. Studies on the fine-scale spatial distribution of corals within reefs provided information on the ecology of CWC

Motion capture based on RGBD data from multiple sensors for avatar animation

With recent advances in technology and emergence of affordable RGB-D sensors for a wider range of users, markerless motion capture has become an active field of research both in computer vision and computer graphics. In this thesis, we designed a POC (Proof of Concept) for a new tool that enables us to perform motion capture by using a variable number of commodity RGB-D sensors of different brands and technical specifications on constraint-less layout environments. The main goal of this work is to provide a tool with motion capture capabilities by using a handful of RGB-D sensors, without imposing strong requirements in terms of lighting, background or extension of the motion capture area. Of course, the number of RGB-D sensors needed is inversely proportional to their resolution, and directly proportional to the size of the area to track to. Built on top of the OpenNI 2 library, we made this POC compatible with most of the nonhigh-end RGB-D sensors currently available in the market. Due to the lack of resources on a single computer, in order to support more than a couple of sensors working simultaneously, we need a setup composed of multiple computers. In order to keep data coherency and synchronization across sensors and computers, our tool makes use of a semi-automatic calibration method and a message-oriented network protocol. From color and depth data given by a sensor, we can also obtain a 3D pointcloud representation of the environment. By combining pointclouds from multiple sensors, we can collect a complete and animated 3D pointcloud that can be visualized from any viewpoint. Given a 3D avatar model and its corresponding attached skeleton, we can use an iterative optimization method (e.g. Simplex) to find a fit between each pointcloud frame and a skeleton configuration, resulting in 3D avatar animation when using such skeleton configurations as key frames

Character modelling for AAA videogames

This work deals with the creation of a 3D character, focused on videogames, inspired by the art of Kingdom Hearts and Disney/Pixar, choosing Ratatouille as the theme of the character. For this, the references used are both from the movies and from the art books of the movie to obtain a character that will be correctly integrated into the video game, since the game is very inspired by the movies, we have tried to obtain an art that is as similar to the film as possible. Realistic hair has been created from technologies that have been investigated such as XGen, which is a Maya tool that allows them to be created. To integrate it into a video game, it has also been studied how to make a correct retopology of the hair since otherwise each hair would be formed by a curve and there may be thousands of them, so rendering them in an engine harms the performance of the scene, each time less due the advances that are being made in them. There has also been an apprenticeship on how to create clothes through other software such as Marvelous Designer, which allows you to create garments through patterns and fabric simulation. Finally, it has been integrated into a 3D engine such as Unreal, to verify that the character works correctly, and animations and poses have been added to present the character in the portfolio. Likewise, renders have also been made with Arnold to create images of the character at a high resolution and detail OBJECTIVES: The main objective of this project is create a 3D character, which can be used in a AAA videogame. The style chosen for this character will be a Disney/Pixar style and the video game in which it would be integrated would be Kingdom Hearts but with a better graphic quality, this means textures with a higher resolution trying to maintain a suitable polygon density for this type of video game. Another objective is the learning and improvement of different processes for the creation of characters