DrawingSpinUp：从单张角色手绘生成3D动画
DrawingSpinUp: 3D Animation from Single Character Drawings
AI总结：
针对单张角色手绘现有动画方法仅能生成2D效果、图像转3D方法处理业余手绘效果差的问题，提出DrawingSpinUp系统，通过轮廓线移除恢复策略和基于骨架的细化变形算法优化外观与几何结构，实现高质量3D动画生成，效果优于现有方法。
摘要：
为各类角色手绘制作动画是一项颇具吸引力的视觉内容创作任务。现有动画方法在输入单张角色手绘时，仅能生成平面2D动作，缺乏3D效果。另一种解决方案是从角色手绘重建3D模型作为代理，再将3D动作数据重定向到该模型上。但现有图像转3D方法在处理业余角色手绘时，无论是外观还是几何结构效果都不佳。我们观察到，角色手绘中普遍存在的轮廓线由于具有视角依赖性，会在纹理合成过程中引入严重的歧义性。此外，由单线条轮廓表示的纤细区域（例如简笔画的细四肢）因结构精巧，重建难度很高。为解决这些问题，我们提出了一套全新系统DrawingSpinUp，可生成合理的3D动画，为角色手绘赋予生命力，让它们能自由旋转、跳跃，甚至表演街舞。在外观优化方面，我们采用“先移除后恢复”的策略：先移除视角依赖的轮廓线，待重建的角色完成动作重定向后，再将轮廓线渲染回去。在几何结构优化方面，我们开发了基于骨架的细化变形算法，对单线条轮廓表示的纤细结构进行优化。实验评估和感知用户研究表明，我们提出的方法优于现有的2D和3D动画方法，能够从单张角色手绘生成高质量的3D动画。代码和生成的动画可参见我们的项目页面：https://lordliang.github.io/DrawingSpinUp。
英文摘要：
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.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
