Post doc proposal
Intuitive creation and editable representation of 3D geometry
Team: EVASION
Advisor: Marie-Paule Cani
Context
With the increase in computational power and of the amount of available memory, the creation of digital
content is becoming one of the major challenges 3D Computer Graphics is facing. Despite the number of
geometric model representations that were developed, little attention has been paid up to now on easing
their use, in order to allow fast and intuitive creation and editing of arbitrary complex shapes:
- Creating or editing a digital shape is still done through complicated interfaces requiring a deep understanding of the underlying shape representation, with its specific degrees of freedom and parameters. This
often requires years of training for a digital artist, and makes shape creation a burden. In consequence,
designers still start with paper and pencil to quickly express their first ideas through gesture and concentrate on the shape, and tend to use the computer only when they have to, at the last stages of design.
- At the same time, the general public is now currently using virtual worlds (from Second Life to
Google Earth), and tools enabling them to personalize it are in great demand, such as creating and placing
shapes they have designed or adding edited versions of existing shapes. The tools needed for this purpose
should be immediately usable, with a minimal learning time, if any.
In this context, the aim of this post doctoral research is two-fold: developing intuitive tools for quickly
creating new 3D free-form shapes, and designing an adaptable representation, also enabling users to rerepresent and edit existing models of arbitrary shape and topological genus. With these methods, the underlying surface representation for the shape should be totally transparent to the user.
Note that this project fits into the “interacting” and “modelling” priorities of the INRIA strategic plan for
2008-2012, since it focuses on intuitive interaction with virtual worlds, and on the development of advanced representations for complex models.
Modeling by tracing and annotating
Designers are often more comfortable working in 2D, for example with pencil-and-paper, than in a 3D
modeling tool. And non-designers may wish to create 3D models from existing 2D images, for instance
through the use of annotation. The goal of this part of the project is to create intuitive tools for users to
trace and mark-up a 2D image to create a 3D model.
Some of the prior work at EVASION already advanced this direction: the Matisse system (see the illustration on the first page) was designed to enable any novice user to create a free form shape by progressively
adding sketched components to a model, under different viewing angles [1]. However, this solution is
quite restrictive since the final shape must be a union of components with flat silhouettes, and complex
drawings sketched from a single drawing angle cannot be interpreted. Other prior work tackled the problem of 3D shape from a single sketch, which could be the annotation of a photo or of a 3D model [2,3,4],
but these techniques, based on a priori knowledge to interpret the sketch, were only developed for specific
objects such as clothing, hair and clouds.
The novelty of this project is tackling the challenge for arbitrary free form shapes, relying on the perception humans have of 3D when they see a 2D representation of a shape.
Surface Re-representation
Complementarily, a representation of surfaces which enables intuitive editing [5] should be developed. A
powerful user interface is one which gives the user few yet intuitive degrees-of-freedom. Two examples
are subdivision control meshes and surface-generating curve networks (such as in FiberMesh). The medial axis, or the skeletons used to create convolution surfaces are other examples. More generally, Leyton’s
theory on the perception and interpretation of shapes [6] gives a very good starting point to define which
kind of handles would be the most intuitive for arbitrary shapes.
This part of the project is aimed at developing such a representation, using it for shapes created through
sketching, and also studying its use to allow the re-representation of existing models of arbitrary topology
and geometry.
Related work
[1] Matisse: Painting 2D regions for Modeling Free-Form Shapes. Bernhardt Adrien, Pihuit Adeline, Cani
Marie-Paule, Barthe Loïc. In EUROGRAPHICS Workshop on Sketch-Based Interfaces and Modeling,
SBIM 2008. Annecy, France, juin 2008. pages 57–64. 2008.
[2] A sketch-based interface for clothing virtual characters. Turquin Emmanuel, Wither Jamie, Boissieux
Laurence, Cani Marie-Paule, Hughes John F. IEEE Comput. Graph. Appl., 27 (1), 72–81, 2007.
[3] Realistic Hair from a Sketch. Wither Jamie, Bertails Florence, Cani Marie-Paule In International Conference on Shape Modeling and Applications, SMI 2007. IEEE, Lyon, France, juin 2007. pages 33–42.
IEEE, 2007.
[4] Rapid sketch modeling of clouds. Wither Jamie, Bouthors Antoine, Cani Marie-Paule In 5th Eurographics Workshop on Sketch-Based Interfaces and Modeling, SBIM 2008. Annecy, France, juin 2008.
pages . 2008.
[5] Interactive Shape Design. Cani Marie-Paule, Igarashi Takeo, Wyvill Geoff. Synthesis Lectures on
Computer Graphics and Animation. Morgan&Claypool Publishers, 2008.
[6] Symmetry, Causality, Mind, M. M. Leyton, The MIT Press, 1992.