Trajectory-aware Smears for Stylized 3D Animations

ACM SIGGRAPH Motion, Interaction and Games 2025 (MIG 2025)

Inria, Univ. Bordeaux, CNRS, Bordeaux INP, LaBRI

3D animation of a jokari (top row) stylized with the approach of Basset et al. (2024) (middle row). High trajectory curvatures in (a) and (e) yield unnatural ball deformations. Our approach (bottom row) corrects this issue (a) and adds squash-and-stretch (e) that is easily blended with smearing effects (c and d) to exaggerate animation around the collision.

Abstract

Smearing is an essential effect to expressively convey motion in stylized animations. In this paper, we extend the method of Basset et al. (2024) to better emphasize the main motion's trajectory of an object when generating elongated in-betweens, i.e., when stretching a 3D object along its trajectory to cover adjacent frames. This limits visual artifacts such as intersections that typically occur when trajectories self-overlap due to local rotations or abrupt changes of direction (trajectories with high curvatures or even discontinuities at contacts). We address these cases with minor computational and memory overheads, and offer enhanced impact expressiveness by combining smear and squash-and-stretch effects at collisions.

Paper

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Supplementary material: Blender scenes with code & videos (180Mo)

Additional Results

Bibtex

@inproceedings{tremolieres:2025,
  title = {Trajectory-aware Smears for Stylized 3D Animations},
  author = {Tremolieres, Lou and Basset, Jean and B{\'e}nard, Pierre and Barla, Pascal},
  booktitle = {MIG 2025 - ACM SIGGRAPH Conference Motion Interaction and Games},
  year = {2025},
  doi = {10.1145/3769047.3769057},      
}