Drawing for Illustration and Annotation in 3D

International audienceWe present a system for sketching in 3D, which strives to preserve the degree of expression, imagination, and simplicity of use achieved by 2D drawing. Our system directly uses user-drawn strokes to infer the sketches representing the same scene from different viewpoints, rather than attempting to reconstruct a 3D model. This is achieved by interpreting strokes as indications of a local surface silhouette or contour. Strokes thus deform and disappear progressively as we move away from the original viewpoint. They may be occluded by objects indicated by other strokes, or, in contrast, be drawn above such objects. The user draws on a plane which can be positioned explicitly or relative to other objects or strokes in the sketch. Our system is interactive, since we use fast algorithms and graphics hardware for rendering. We present applications to education, design, architecture and fashion, where 3D sketches can be used alone or as an annotation of an existing 3D model

Shape Modeling by Sketching using Convolution Surfaces

International audienceThis paper proposes a user-friendly modeling system that interactively generates 3D organic-like shapes from user drawn sketches. A skeleton, in the form of a graph of branching polylines and polygons, is first extracted from the user's sketch. The 3D shape is then defined as a convolution surface generated by this skeleton. The skeleton's resolution is adapted according to the level of detail selected by the user. The subsequent 2D strokes are used to infer new object parts, which are combined with the existing shape using CSG operators. We propose an algorithm for computing a skeleton defined as a connected graph of polylines and polygons. To combine the primitives we propose precise CSG operators for a convolution surfaces blending hierarchy. Our new formulation has the advantage of requiring no optimization step for fitting the 3D shape to the 2D contours. This yields interactive performances and avoids any non-desired oscillation of the reconstructed surface. As our results show, our system allows nonexpert users to generate a wide variety of free form shapes with an easy to use sketch-based interface

2.5D cartoon models

We present a way to bring cartoon objects and characters into the third dimension, by giving them the ability to rotate and be viewed from any angle. We show how 2D vector art drawings of a cartoon from different views can be used to generate a novel structure, the 2.5D cartoon model, which can be used to simulate 3D rotations and generate plausible renderings of the cartoon from any view. 2.5D cartoon models are easier to create than a full 3D model, and retain the 2D nature of hand-drawn vector art, supporting a wide range of stylizations that need not correspond to any real 3D shape.MathWorks, Inc. (Fellowship

An investigation on the framework of dressing virtual humans

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Realistic human models are widely used in variety of applications. Much research has been carried out on improving realism of virtual humans from various aspects, such as body shapes, hair, and facial expressions and so on. In most occasions, these virtual humans need to wear garments. However, it is time-consuming and tedious to dress a human model using current software packages [Maya2004]. Several methods for dressing virtual humans have been proposed recently [Bourguignon2001, Turquin2004, Turquin2007 and Wang2003B]. The method proposed by Bourguignon et al [Bourguignon2001] can only generate 3D garment contour instead of 3D surface. The method presented by Turquin et al. [Turquin2004, Turquin2007] could generate various kinds of garments from sketches but their garments followed the shape of the body and the side of a garment looked not convincing because of using simple linear interpolation. The method proposed by Wang et al. [Wang2003B] lacked interactivity from users, so users had very limited control on the garment shape.This thesis proposes a framework for dressing virtual humans to obtain convincing dressing results, which overcomes problems existing in previous papers mentioned above by using nonlinear interpolation, level set-based shape modification, feature constraints and so on. Human models used in this thesis are reconstructed from real human body data obtained using a body scanning system. Semantic information is then extracted from human models to assist in generation of 3 dimensional (3D) garments. The proposed framework allows users to dress virtual humans using garment patterns and sketches. The proposed dressing method is based on semantic virtual humans. A semantic human model is a human body with semantic information represented by certain of structure and body features. The semantic human body is reconstructed from body scanned data from a real human body. After segmenting the human model into six parts some key features are extracted. These key features are used as constraints for garment construction.Simple 3D garment patterns are generated using the techniques of sweep and offset. To dress a virtual human, users just choose a garment pattern, which is put on the human body at the default position with a default size automatically. Users are allowed to change simple parameters to specify some sizes of a garment by sketching the desired position on the human body.To enable users to dress virtual humans by their own design styles in an intuitive way, this thesis proposes an approach for garment generation from user-drawn sketches. Users can directly draw sketches around reconstructed human bodies and then generates 3D garments based on user-drawn strokes. Some techniques for generating 3D garments and dressing virtual humans are proposed. The specific focus of the research lies in generation of 3D geometric garments, garment shape modification, local shape modification, garment surface processing and decoration creation. A sketch-based interface has been developed allowing users to draw garment contour representing the front-view shape of a garment, and the system can generate a 3D geometric garment surface accordingly. To improve realism of a garment surface, this thesis presents three methods as follows. Firstly, the procedure of garment vertices generation takes key body features as constraints. Secondly, an optimisation algorithm is carried out after generation of garment vertices to optimise positions of garment vertices. Finally, some mesh processing schemes are applied to further process the garment surface. Then, an elaborate 3D geometric garment surface can be obtained through this series of processing. Finally, this thesis proposes some modification and editing methods. The user-drawn sketches are processed into spline curves, which allow users to modify the existing garment shape by dragging the control points into desired positions. This makes it easy for users to obtain a more satisfactory garment shape compared with the existing one. Three decoration tools including a 3D pen, a brush and an embroidery tool, are provided letting users decorate the garment surface by adding some small 3D details such as brand names, symbols and so on. The prototype of the framework is developed using Microsoft Visual Studio C++,OpenGL and GPU programming

Paper and pen: A 3D sketching system

This paper proposes a method that resembles a natural pen and paper interface to create curve based 3D sketches. The system is particularly useful for representing initial 3D design ideas without much effort. Users interact with the system by the help of a pressure sensitive pen tablet. The input strokes of the users are projected onto a drawing plane, which serves as a paper that they can place anywhere in the 3D scene. The resulting 3D sketch is visualized emphasizing depth perception. Our evaluation involving several naive users suggest that the system is suitable for a broad range of users to easily express their ideas in 3D. We further analyze the system with the help of an architect to demonstrate the expressive capabilities. © 2013 Springer-Verlag London

A Sketching Interface for Garment Design

National audienceThe range of approaches used for clothing virtual characters is large: for incidental characters, the clothing may be no more than a texture map. For lead characters in feature films, full-fledged physical simulation of detailed cloth models may be used. And in the midrange, simple skinning techniques, combined with texture mapping, are common, providing some deformation of clothing as the character moves, but no physical realism. There are three problems one can associate with clothing virtual characters: the design of the clothes (tailoring), placing them on the character (dressing), and making them look physically correct (typically through simulation). The process of tailoring involves choosing the cloth and fitting it to the body, often making adjustments in the patterns of the cloth to adapt it to the particular person's body shape, and then sewing it. For virtual characters, clothing often has no "patterns" from which it is sewn, instead it is represented by a simple polygonal mesh that is constructed to fit the body. It's currently tedious to construct such meshes even without the issues of patterns and stitching. It's sometimes done by directly incorporating the cloth mesh into a character's geometric model, so that the character doesn't actually have legs, for instance, but just pants (see figure 1.1). In this case physical simulation is no longer a possibility, and when a character needs new clothes, it must be largely re-modeled. An alternative approach involves drawing pattern pieces for a garment and positioning them over the naked form of the character, defining stitching constraints, etc. This can be tedious, especially when the character is not important enough to merit this amount of effort; it also requires an understanding of how cloth fits over shapes, although the actual pattern-and-stitching information may not be relevant after the tailoring is completed (except in the rare case where the physical properties of the cloth -- was it cut on the bias? Does the cloth resist folding along one axis? -- are later used in a full-fledged physical simulation). Our approach combines tailoring and dressing into a single step to create a mesh that's suitable for later simulation or skinning approaches. The idea is to make it easy to generate simple garments that are adapted to an existing model. We believe that most people know better how to draw garments than the patterns which are needed to sew them. The aim of this work is thus to explore the use of a sketch-based interface for quickly constructing 3D virtual garments over a character model. This report describes simple solutions to the problems of shape generation and placement of the clothing. The resulting system is so easy to use that it takes only few minutes to create a simple garment

Digitalization of the product development process at Scania engine assembly

The technology is constantly developing and companies are striving to work towards a more digital approach. Scania CV AB is a world leading Company manufacturing buses and trucks for heavy transport applications. To maintain their competitive position at the market the company has the ambition for the Product development process to become more digitalized. A goal is to implement a more simulation based and drawing free working method. This project has been carried out at the engine assembly department. The purpose with the thesis was to identify how parts of the product development process could be more digitalized. This included identifying the gap that will occur between the current working process and a more digital approach. Furthermore, it involved finding solutions for the gap and to present possible impacts of a digital working approach. The initial phase of the thesis was to find a suitable methodology for this type of study. The project proceeded with conducting a literature study to gain deeper insight of the subjects covered. A good foundation was obtained and the empirical study could commence. The data collection in the empirical study was gathered mainly within Scania through interviews, observations and archive analyses. Based on this information an analysis and result was carried out and presented. A gap was identified describing deficient areas in the current digital environment. The working method Model Based Definition (MBD) and a software called Industrial Path Solutions (IPS) are presented as solutions for the gap. Suggestions of how the working process should be modified have been set as prerequisites. Impacts including cost savings, quality improvements, shorter lead times and ergonomic benefits have been submitted.Tekniken utvecklas ständigt och företag strävar därför att arbeta mot ett mer digitalt arbetssätt. Scania CV AB är ett världsledande företag som tillverkar bussar och lastbilar för tunga transporter. För att behålla sin konkurrenskraftiga position på marknaden har företaget ambitionen att göra produktutvecklingsprocessen mer digitaliserad. Ett mål är att utveckla en mer simuleringsbaserad och ritningslös arbetsmetod. Detta projekt har genomförts på produktionsavdelningen där montering av motorer sker. Syftet med uppsatsen var att identifiera hur delar av den nuvarande produktutvecklingsprocessen skulle kunna bli mer digitaliserad. Detta innebar att identifiera det gap som kommer att uppstå mellan den nuvarande arbetsprocessen och ett mer digitaliserat tillvägagångssätt. Lösningar på gapet och effekterna av ett mer digitalt arbete skulle också presenteras. Den inledande delen av arbetet innefattade att hitta en lämplig metod för denna typ av studie. Projektet fortskred med en litteraturstudie för att få djupare inblick i de ämnen som projektet kommer att grundas i. Med en bra grundförståelse kunde en empirisk studie påbörjas. Datainsamlingen till den empiriska studien samlades huvudsakligen in på Scania genom intervjuer, observationer och arkivanalyser. Baserat på denna information genomfördes och presenterades en analys och ett resultat. Ett gap som beskriver de bristfälliga områden i den nuvarande digitala miljön identifierades. Arbetsmetoden Model Based Definition (MBD) och mjukvaran Industrial Path Solutions (IPS) presenterades som lösningar på gapet. Även förslag på hur arbetsprocessen kan ändras för att möjliggöra för ett mer digitalt tillvägagångssätt har redogjorts. Följderna av detta som inkluderar kostnadsbesparingar, kvalitetsförbättringar, kortare ledtider och ergonomifördelar har också sammanställts

Vers l'élimination des dessins d'ingénierie des processus de modification d'ingénierie en aéronautique

La définition du produit est aujourd’hui composée et véhiculée par des modèles 3D et des dessins 2D tout au long du cycle de vie du produit. Grâce aux progrès portant sur la définition de la maquette numérique, les entreprises, notamment celles des secteurs automobile et aéronautique, s’intéressent à l’approche Model-based Definition (MBD) qui promet de réduire les temps de mise en marché et d’améliorer la qualité des produits. Sa finalité est d’accélérer et améliorer les processus de conception, de fabrication et d’inspection en intégrant les annotations, traditionnellement portées par les dessins d’ingénierie, directement dans le modèle 3D, provoquant ainsi une diminution significative de la production de dessins. Malgré l’existence de standards internationaux et d’outils CAO spécifiques pour supporter le concept MBD, son implémentation n’a pas été encore entièrement adoptée tout au long du cycle de vie du produit. Les dessins d’ingénierie traditionnels assument encore différentes fonctions perçues comme essentielles telles que la capture et la distribution des données non géométriques (tolérances, notes, etc.), le stockage à long terme de la définition des produits, de même que dans la gestion des modifications d’ingénierie. Particulièrement, le processus de gestion des modifications (PGM) d’ingénierie implique l’étude, l’annotation, la révision, la validation et la libération des dessins d’ingénierie. L’exploration des alternatives de réingénierie du PGM en absence de dessins devient alors une démarche nécessaire vers l’adoption de l’approche MBD. L’objectif de ce projet de recherche est donc de proposer une solution permettant l’exécution du PGM dans un environnement sans dessins et de quantifier les gains potentiels. Deux entreprises canadiennes du secteur aéronautique sont impliquées dans ce projet de recherche. Dans un premier temps, les obstacles qui doivent être surmontés pour permettre l’adoption de l’initiative MBD sont identifiés. Nos observations sont le résultat de quarante-et-une entrevues effectuées dans les départements d’ingénierie, gestion de la configuration, navigabilité, certification, fabrication, inspection et gestion des connaissances chez les partenaires industriels. Les résultats des entrevues indiquent qu’il est nécessaire de définir clairement la façon dont la définition du produit va être véhiculée en absence des dessins tout en supportant les besoins spécifiques provenant de chacun des clients de la définition du produit. Par la suite, une solution permettant l’exécution du PGM dans un contexte MBD est développée et évaluée en se basant sur les caractéristiques et spécifications du PGM chez les partenaires industriels. La solution consiste à définir un ensemble des données qui est composée du modèle 3D annoté (généré par le système CAO) et du fichier de distribution (généré et exploité par l’application de visualisation) sous format allégé. L’exercice de réingénierie du PGM est réalisé en fonction de la solution proposée. Finalement, les gains issus de la solution proposée sont évalués et quantifiés. Une approche par simulation à événements discrets est adoptée en considérant des données empiriques et expérimentales provenant de l’un des partenaires industriels. Des réductions d’environ 11% du temps et du coût moyen d’exécution du processus sont obtenues