2022-05235 - Post-Doctoral Research Visit F/M Space-time 3D animation stylization

Contract type : Fixed-term contract

Level of qualifications required : PhD or equivalent

Fonction : Post-Doctoral Research Visit

About the research centre or Inria department

The manao project aims at studying how light, matter and shape act together in synergies, at the convergence of Digital Optics and Computer Graphics, providing for more powerful representations of appearance. Such a high-level approach is to contrast with the main trend of modern Computer Graphics to study light, shape and matter separately.


This posdoctoral position is part of the MoStyle project funded by the French National Research Agency (ANR).


The overall goal of this project is to investigate how computer tools can help capturing and reproducing the typicality of traditional 2D animations. More precisely, we plan to address the following two challenges:

  1. How to interactively generate in-betweening frames from a sparse sequence of rough drawings to swiftly explore different animation choices and motion designs.
  2. How to stylize the geometry and motion of a 3D animation to allow its seamless integration into a 2D animation.

These two objectives target tasks that are currently tedious to perform by artists; they currently rely on manual techniques or ad‐hoc solutions that severely limit artistic creativity and drastically increase production times. The solutions that we will develop in the project should be compatible with regular animation workflows and should provide adequate controls to artists that should remain at the center of the computer‐human interaction loop.

This postdoc will tackle the second challenge of this project which aims at  stylizing the geometry and motion of a 3D animation to enable its seamless integration into a 2D animation. The final objective is to provide artists with controllable space-time “modifiers” that locally deform an input 3D animation in such a way that obvious 3D cues – that a 2D animator would not draw – are hidden, whereas desirable traditional 2D animation effects [1] (squash-and-stretch, anticipation and follow through…) are produced.


Main activities

Our key insight to achive this goal is to use surface contours as a basis for those modifiers. To drive the modifiers in space and time, we will need to structure this set of contours inside the space-time window enclosing the edit which implies to establish temporal correspondences between those lines. Yet, unlike previous approaches that were constructing the entire space-time surface [2] spanned by the curve network over the course of the animation, or encoding it into a global temporal Planar Map [3], we would like to build a lightweight local structure restricted to the working domain of the modifier. In most cases, this will avoid the computational cost and technical complexity of building and maintaining a global data-structure. Nevertheless, this approach supposes to be able to efficiently determine correspondences on demand when the modifier requires it, which is an interesting technical problem.

Once this local space-time structure is constructed, we can experiment with various  filters and deformers, such as Laplacian smoothing, the fitting of geometric primitives (e.g., arcs, line segments, clothoids), 2D+t and 3D+t warps. The challenge is to determine which of those manipulations are producing plausible line drawings without introducing disturbing residual motion, and how artists can intuitively control them. Sketching seems a natural direction to follow, but an example-based approach is also worth investigating.

[1]    R. Williams. The Animator’s Survival Kit: A Manual of Methods, Principles and Formulas for Classical, Computer, Games, Stop Motion and Internet Animators. Faber & Faber Inc. 2009. http://www.theanimatorssurvivalkit.com

[2]    B. Buchholz, N. Faraj, S. Paris, E. Eisemann, and T. Boubekeur. Spatio-Temporal Analysis for Parameterizing Animated Lines. Proc. of the Inter. Symp. on Non-Photorealistic Animation and Rendering, 2011. https://doi.org/10.1145/2024676.2024690

[3]    B. Dalstein, R. Ronfard, M. van de Panne. Vector Graphics Animation with Time-Varying Topology ACM Transactions on Graphics, 34, 4 (SIGGRAPH 2015). https://doi.org/10.1145/2766913


The successful candidate should have a PhD in Computer Graphics with strong experience in C++/OpenGL programming, and a strong general background in both Mathematics and Computer Science.

Additional skills in some of the following topics would be appreciated: expressive rendering, geometry processing, user interfaces.

Personal interest for drawing and/or 2D-3D animation would be a plus.


Benefits package

  • Subsidized meals
  • Partial reimbursement of public transport costs
  • Possibility of teleworking and flexible organization of working hours
  • Professional equipment available (videoconferencing, loan of computer equipment, etc.)
  • Social, cultural and sports events and activities
  • Access to vocational training
  • Social security coverage


2746€ / month (before taxs)