Computer Graphics Laboratory ETH Zurich

ETH

Sketch Abstractions for Character Posing

F. Hahn, F. Mutzel, S. Coros, B. Thomaszewski, M. Nitti, M. Gross, R. Sumner

Proceedings of the 2015 ACM SIGGRAPH/Eurographics Symposium on Computer Animation (Los Angeles, California, USA, August 7-9, 2015), pp. 185-191
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Abstract

We propose a sketch-based posing system for rigged 3D characters that allows artists to create custom sketch abstractions on top of a character's actual shape. A sketch abstraction is composed of rigged curves that form an iconographic 2D representation of the character from a particular viewpoint. When provided with a new input sketch, our optimization system minimizes a nonlinear iterative closest point energy to find the rigging parameters that best align the character's sketch abstraction to the input sketch. A custom regularization term addresses the underconstrained nature of the problem to select favorable poses. Although our system supports arbitrary black-box rigs, we show how to optimize computations when rigging formulas and derivatives are available. We demonstrate our system's flexibility with examples showing different artist-designed sketch abstractions for both full body posing and the customization of individual components of a modular character. Finally, we show that simple sketch abstractions can be built on the fly by projecting a drawn curve onto the character's mesh. Redrawing the curve allows the user to dynamically pose the character. Taken together, our system enables a new form of intuitive sketch-based posing in which the character designer has the freedom to prescribe the sketch abstraction that is most meaningful for the character.

@inproceedings{Hahn15Sketch,
author = {Hahn, Fabian and Mutzel, Frederik and Coros, Stelian and Thomaszewski, Bernhard and Nitti, Maurizio and Gross, Markus and Sumner, Robert W.},
title = {Sketch Abstractions for Character Posing},
booktitle = {Proceedings of the 14th ACM SIGGRAPH / Eurographics Symposium on Computer Animation},
series = {SCA '15},
year = {2015},
isbn = {978-1-4503-3496-9},
location = {Los Angeles, California},
pages = {185--191},
numpages = {7},
url = {http://doi.acm.org/10.1145/2786784.2786785},
doi = {10.1145/2786784.2786785},
acmid = {2786785},
publisher = {ACM},
address = {New York, NY, USA},
keywords = {character individualization, sketch-based posing},
}
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