DrawingSpinUp: 3D Animation from Single Character Drawings
Authors: name: Jie Zhou, name: Chufeng Xiao, name: Miu-Ling Lam, name: Hongbo Fu

Animating various character drawings is an engaging visual content creation
task. Given a single character drawing, existing animation methods are limited
to flat 2D motions and thus lack 3D effects. An alternative solution is to
reconstruct a 3D model from a character drawing as a proxy and then retarget 3D
motion data onto it. However, the existing image-to-3D methods could not work
well for amateur character drawings in terms of appearance and geometry. We
observe the contour lines, commonly existing in character drawings, would
introduce significant ambiguity in texture synthesis due to their
view-dependence. Additionally, thin regions represented by single-line contours
are difficult to reconstruct (e.g., slim limbs of a stick figure) due to their
delicate structures. To address these issues, we propose a novel system,
DrawingSpinUp, to produce plausible 3D animations and breathe life into
character drawings, allowing them to freely spin up, leap, and even perform a
hip-hop dance. For appearance improvement, we adopt a removal-then-restoration
strategy to first remove the view-dependent contour lines and then render them
back after retargeting the reconstructed character. For geometry refinement, we
develop a skeleton-based thinning deformation algorithm to refine the slim
structures represented by the single-line contours. The experimental
evaluations and a perceptual user study show that our proposed method
outperforms the existing 2D and 3D animation methods and generates high-quality
3D animations from a single character drawing. Please refer to our project page
(https://lordliang.github.io/DrawingSpinUp) for the code and generated
animations.