DrawingSpinUp: 3D Animation from
Single Character Drawings

Jie Zhou, Chufeng Xiao, Miu-Ling Lam, and Hongbo Fu

Abstract

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 show that our method outperforms the existing 2D and 3D animation methods and generates high-quality 3D animations from single character drawings.

Method


Comparisons to Prior Work


Comparison-1: We compare our method to a 2D-based animation method: Smith et al. [2023] .


Input Drawings
3D Motions
Smith et al.
Ours

Comparison-2: We compare our method to other 3D-based animation methods: DreamGaussian [2023] and Wonder3D [2023] .


Input Drawings
DreamGaussian
Wonder3D
Ours

Ablation


(a) Contour Removal

Comparison between without (Top) and with (Bottom) contour removal.

(b) Shape Refinement

Comparison of three scenarios: no-cut-no-thin (Top), only-cut (Middle), and cut-and-thin (Bottom).

(c) Rotation-Invariant Convolution

Comparison between without (Top) and with (Bottom) rotation-invariant convolution.

Limitations



Inappropriate Edge Extraction

Our contour rendering might produce artifacts when we extract edges with inappropriate thresholds, as shown in the red dotted circles.

Hard Examples with Too Thick Contour Lines

When the contour lines of the input drawing are too thick, artifacts may appear in the generated results, as indicated by the red dotted circles.

BibTeX


        @inproceedings{zhou2024drawingspinup,
          author    = {Zhou, Jie and Xiao, Chufeng and Lam, Miu-Ling and Fu, Hongbo},
          title     = {DrawingSpinUp: 3D Animation from Single Character Drawings},
          booktitle = {SIGGRAPH Asia 2024 Conference Papers},
          year      = {2024},
        }