filename     : Hahn15a.pdf
entry        : inproceedings
conference   : SCA 2015, Los Angeles, USA, 7-9 August, 2015
pages        : 7
year         : 2015
month        : August
title        : Sketch Abstractions for Character Posing
subtitle     :
author       : Hahn, Fabian and Mutzel, Frederik and Coros, Stelian and Thomaszewski, Bernhard and Nitti, Maurizio and Gross, Markus and Sumner, Robert W.
booktitle    : Proceedings of the ACM SIGGRAPH/Eurographics Symposium on Computer Animation
ISSN/ISBN    :
editor       : 
publisher    : ACM
publ.place   : New York, NY, USA
volume       : 
issue        :
language     : english
keywords     : sketch-based posing, character individualization
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.