374 research outputs found

    Space-time sketching of character animation

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    International audienceWe present a space-time abstraction for the sketch-based design of character animation. It allows animators to draft a full coordinated motion using a single stroke called the space-time curve (STC). From the STC we compute a dynamic line of action (DLOA) that drives the motion of a 3D character through projective constraints. Our dynamic models for the line's motion are entirely geometric, require no pre-existing data, and allow full artistic control. The resulting DLOA can be refined by over-sketching strokes along the space-time curve, or by composing another DLOA on top leading to control over complex motions with few strokes. Additionally , the resulting dynamic line of action can be applied to arbitrary body parts or characters. To match a 3D character to the 2D line over time, we introduce a robust matching algorithm based on closed-form solutions, yielding a tight match while allowing squash and stretch of the character's skeleton. Our experiments show that space-time sketching has the potential of bringing animation design within the reach of beginners while saving time for skilled artists

    3D free-form modeling with variational surfaces

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    We describe a free-form stroke-based modeling system where objects are primarily represented by means of variational surfaces. Although similar systems have been described in recent years, our approach achieves both a good performance and reduced surface leak problems by employing a coarse mesh as support for constraint points. The prototype implements an adequate set of modeling operations, “undo” and “redo” facilities and a clean interface capable of resolving ambiguities by means of suggestion thumbnails

    Sketching space

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    In this paper, we present a sketch modelling system which we call Stilton. The program resembles a desktop VRML browser, allowing a user to navigate a three-dimensional model in a perspective projection, or panoramic photographs, which the program maps onto the scene as a `floor' and `walls'. We place an imaginary two-dimensional drawing plane in front of the user, and any geometric information that user sketches onto this plane may be reconstructed to form solid objects through an optimization process. We show how the system can be used to reconstruct geometry from panoramic images, or to add new objects to an existing model. While panoramic imaging can greatly assist with some aspects of site familiarization and qualitative assessment of a site, without the addition of some foreground geometry they offer only limited utility in a design context. Therefore, we suggest that the system may be of use in `just-in-time' CAD recovery of complex environments, such as shop floors, or construction sites, by recovering objects through sketched overlays, where other methods such as automatic line-retrieval may be impossible. The result of using the system in this manner is the `sketching of space' - sketching out a volume around the user - and once the geometry has been recovered, the designer is free to quickly sketch design ideas into the newly constructed context, or analyze the space around them. Although end-user trials have not, as yet, been undertaken we believe that this implementation may afford a user-interface that is both accessible and robust, and that the rapid growth of pen-computing devices will further stimulate activity in this area

    Results of an observational study on sketching

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    We present the results of an observational study on sketching. Artists were asked to sketch a small number of objects and comment on how and why they made the marks they did. We summarize these findings, from low-level details on individual marks through the drawing construction order. Based on these observations we provide suggestions for future research directions in 3D sketching

    SmartCanvas: Context-inferred Interpretation of Sketches for Preparatory Design Studies

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    In early or preparatory design stages, an architect or designer sketches out rough ideas, not only about the object or structure being considered, but its relation to its spatial context. This is an iterative process, where the sketches are not only the primary means for testing and refining ideas, but also for communicating among a design team and to clients. Hence, sketching is the preferred media for artists and designers during the early stages of design, albeit with a major drawback: sketches are 2D and effects such as view perturbations or object movement are not supported, thereby inhibiting the design process. We present an interactive system that allows for the creation of a 3D abstraction of a designed space, built primarily by sketching in 2D within the context of an anchoring design or photograph. The system is progressive in the sense that the interpretations are refined as the user continues sketching. As a key technical enabler, we reformulate the sketch interpretation process as a selection optimization from a set of context-generated canvas planes in order to retrieve a regular arrangement of planes. We demonstrate our system (available at http:/geometry.cs.ucl.ac.uk/projects/2016/smartcanvas/) with a wide range of sketches and design studies

    Sketching as a communication tool and a vehicle for exploring new ideas in Higher Education of industrial design. Implementation and analysis of new methodologies

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    [EN] Freehand drawing is a basic tool to explore shapes and visualize ideas during the first phase of projective process in industrial design. Sketches, expressive and quickly executed, allow designers to highlight the most interesting aspects of the product to be designed and help to define its shape and general features. Due to the immediacy that characterizes the manual drafting industrial designers in training learn to become able to translate any ideas graphically and thus able to communicate with other designers, initiating a dialogue on the product to be designed. In the Bachelor's Degree in Industrial Design and Product Development Engineering at the Jaume I University of Castellón (Spain), the subject 'Artistic Expression II' maintains and strengthens the knowledge gained in other subjects about the different graphic techniques, making drawing a means of expression for represent, synthesize and define the shape of objects. However, it has been found that the subject procedures were not adequate to achieve the learning results proposed, so it was necessary to apply a new approach. This paper describes the implementation of a new methodological strategy on this subject, adapting it to the European Higher Education Area, with the aim that students in Industrial Design acquire the four core competences of this matter. We describe the activities designed to achieve each of the competences and the implemented methodology for each of these activities. Finally, the results are analyzed and the overall positive impact of the measures taken is discussed.The methodologies conducted in this subject are part of the educational improvement project with reference 3049/15, which has received funding from the Educational Support Unit (U.S.E.) of the Jaume I University, through the annual program 'Aids for educational innovation projects at the Jaume I University in the 2015/16 course'.Navarro, JL.; Felip Miralles, F. (2017). Sketching as a communication tool and a vehicle for exploring new ideas in Higher Education of industrial design. Implementation and analysis of new methodologies. Multidisciplinary Journal for Education, Social and Technological Sciences. 4(2):26-46. doi:10.4995/muse.2017.6349SWORD264642Carnevale, V. (2015). «To Design» or «To Draw»: Two Different Verbs, Two Different Abilities, One Result. The International Journal of Designed Objects, 8(1), 17-25. doi:10.18848/2325-1379/cgp/v08i01/38695Dong, H., Cifter, A. S., & Fan, Z. (2013). Methods for Improving Undergraduate Students’ Sketching Skills. International Journal of Mechanical Engineering Education, 41(4), 329-336. doi:10.7227/ijmee.41.4.7Herbert, D. M. (1988). Study Drawings in Architectural Design: Their Properties as a Graphic Medium. Journal of Architectural Education, 41(2), 26-38. doi:10.1080/10464883.1988.10758473Laseau, P. (2001). Graphic Thinking for Architects and Designers. New York: John Wiley & Sons.Travis, S. (2014). Sketching as a Tool for Seeing: A Method for Teaching Drawing to Architecture and Interior Design Students. The International Journal of Design Education, 7(3), 63-74. doi:10.18848/2325-128x/cgp/v07i03/3845

    Animation de personnages 3D par le sketching 2D

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    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

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    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

    On expert performance in 3D curve-drawing tasks

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    A study is described which examines the drawing accuracy of experts when drawing foreshortened projections of 3D curves in ecologically-valid conditions. The main result of this study is that the distribution of error in expert drawings exhibits a bias similar to that previously observed in non-expert subjects, which is dependent on the degree of foreshortening of the imagined drawing surface. A review of existing perceptual studies also finds that only absolute 2D image-space error has been considered, which has been found to be largest with viewing angles of 25-55 ◦. Our visualizations of 3D error indicate that 3D bias continues to increase with decreasing viewing angle. Based on these findings, we analyze current 3D curve drawing techniques for susceptibility to foreshortening bias, and make suggestions for future sketch-based modeling systems

    A projective approach to computer-aided drawing

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Architecture, 2001.Includes bibliographical references (p. 92-95).I present a novel drawing system for composing and rendering perspective scenes. The proposed approach uses a projective two-dimensional representation for primitives rather than a conventional three-dimensional description. This representation is based on points that lie on the surface of a unit sphere centered at the viewpoint. It allows drawings to be composed with the same ease as traditional illustrations, while providing many of the advantages of a three-dimensional model. I describe a range of user-interface tools and interaction techniques that give the drawing system its three-dimensional-like capabilities. The system provides vanishing point guides and perspective grids to aid in drawing freehand strokes and composing perspective scenes. The system also has tools for intuitive navigation of a virtual camera, as well as methods for manipulating drawn primitives so that they appear to undergo three-dimensional translations and rotations. The new representation also supports automatic shading of primitives using either realistic or non-photorealistic styles. My system supports drawing and shading of extrusion surfaces with automatic hidden surface removal and emphasized silhouettes. Casting shadows from an infinite light source is also possible with minimal user intervention. I describe a method for aligning a sketch drawn outside the system using its vanishing points, allowing the integration of computer sketching and freehand sketching on paper in an iterative manner. Photographs and scanned drawings are applied to drawing primitives using conventional texture-mapping techniques, thereby enriching drawings and providing another way of incorporating hand-drawn images. I demonstrate the system with a variety of drawings.by Osama S. Tolba.Ph.D
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