ISk2011 project (Implicit Skinning)

Presentation

This projects explores the possibilities offered by a novel theoretical way of addressing character deformations: the implicit skinning. This method jointly uses meshes (the standard representation for 3D animations) and volumetric scalar functions (usually restricted to collision detections). The strength of this approach is to provide effective solutions when meshes reach their limits by exploiting, in these situations, the natural properties of 3D scalar functions, such as their ability to generate multiple collisionfree isosurfaces. By improving the theoretical properties of scalar functions, the way they can be represented, evaluated and deformed in real-time, and studying their joint use with meshes, we aim at finding effective solutions allowing production studios to integrate in their production pipeline automatic and plausible character deformations. Such solutions would have a very significant impact on the realism of the final animations as well as on the time required for their creation. From the academic point of view, the impact is also important as this research is a scientific break with the current geometric or physically-based approaches and it offers new perspectives that are considered extremely challenging to reach.

Software

• Maya Plug-in based on our TOG 2013 and 2014 papers (06/2018): - Coming Soon - currently under ALPHA tests - We are developing a demo Maya plug-in to demonstrate the capabilities of the implicit skinning in production. This plug-in illustrates the current version of both the time independent and the time dependent versions of the implicit skinning. It is based on the methods presented in our TOG 2013 and 2014 (see below) improved with some new under-valorization content. You can contact Antonin Crosson and Jérôme Lelasseux (crosson at toulouse-tech-transfer.com, lelasseux at toulouse-tech-transfer.com) at Toulouse Tech Transfer for more information.

• Demo software based on our TOG 2014 paper (06/2018): - Coming Soon - currently under BETA tests - Demo stand-alone software for Linux, Mac OS and Windows. This demo includes three models (capsul, hand and Dana) and a hip-hop animation (for Dana). It also allows you to export meshes at the OBJ format. It illustrates the current version of the time dependent version of the implicit skinning. It is based on the method presented in our TOG 2014 (see below) improved with some new under-valorization content.

• Prototype codes for our TOG 2013 paper (11/2014): Our codes implementing the implicit skinning technique are distributed under GPL3 license. Note that they are old research codes produced for our TOG 2013 paper. All informations here

• IBL: Our binary composition operators for 3D scalar functions are implemented in the Implicit Blending Library. It is accessible under academic only license. Note that these are old research codes produced for our TOG 2013 papers. All informations here.

Resources

• Lots of resources can be found on Rodolphe Vaillant website:

  • An implementation guide for the 2013 version (including codes for the HRBFs).
  • A set of tutrials on the required knowledge (dual quaternions, smoothing, cotangent weigths, etc).

Partners involved in the project, current and past

Academic Institutions, current and past

Industrial Partners, current and past

Results

Sketch-based Implicit Composition

This video illustrates our new gradient-based composition operator for combining implicit surfaces. The free-form shape linking the combined objects is inferred from user sketches. Published at Siggraph Asia 2017 (Transaction on Graphics 36(6)).

Elastic Implicit Skinning

This video illustrates the use of field function compositions for improving the realism of skin deformations at joints when animating an articulated model. A tangential relaxation scheme derived from the ARAP energy controls mesh distortions. This technique is interactive and improves field function based mesh deformations. Published at Siggraph Asia 2014 (Transactions on Graphics 33(6)).

Implicit Skinning

This video illustrates the use of field function compositions for improving the realism of skin deformations at joints when animating an articulated model with geometric skinning. This technique performs in real-time and introduces the concept of field function based mesh deformations, especially in the presence of contact. This research has been published at Siggraph 2013 (Transactions on Graphics 32(4)).

Gradient-Based Blending

This video illustrates how the composition of implicit surfaces using union, intersection, difference, blending and bulge-in-contact can be done in an effective manner by avoiding standard artefacts (blend at distance, unwanted bulge, etc). This theoretical research work has been published in Transactions on Graphics 2013 (32(2)).

Animated VORTEX's Logo

Using the results presented in "A Gradient-Based Implicit Blend" by Gourmel et al (partially funded by IM&M), only five equations and a simple ray-tracer are required to produce this video. We use three field functions of R3 in R for representing the ground, the logos sheres and removed extruded object. We also use two operators of R2 in R: one clean union/difference operator for the construction of the logo and one bulge-in-contact operator to handle its deformation when it comes in contact with the ground. All contact deformations are thus automatically generated. In this animation, no collision test and no mesh is used.

Publications

Journals

	2017 B. Angles, M. Tarini, B. Wyvill, L. Barthe and A. Tagliasacchi. "Sketch-Based Implicit Blending", ACM Transactions on Graphics, 36(6), proc. of ACM SIGGRAPH ASIA, 2017. [pdf] [YouTube]
	2014 R. Vaillant, G. Guennebaud, L. Barthe, M.P. Cani and B. Wyvill. "Robust Iso-Surface Tracking for Interactive Character Skinning", ACM Transactions on Graphics, 33(6), proc. of ACM SIGGRAPH ASIA, 2014. [pdf] [video] [vimeo] [YouTube] [transfer] [more]
	2013 R. Vaillant, L. Barthe, G. Guennebaud, M.P. Cani, D. Rhomer, B. Wyvill, O. Gourmel and M. Paulin. "Implicit Skinning: Real-Time Skin Deformation with Contact Modeling", ACM Transactions on Graphics, 32(4), proc. of ACM SIGGRAPH, 2013. [pdf] [video] [vimeo] [YouTube] [transfer] [free codes] [more]
	2013 O.Gourmel, L. Barthe, M.P. Cani, B. Wyvill, A. Bernhardt, M. Paulin and H. Grasberger. "A Gradient-Based Implicit Blend", ACM Transactions on Graphics, 32(2), presented at SIGGRAPH in July 2013. [pdf] [video] [vimeo] [free codes]

Conferences

In French

2012 R. Vaillant, L. Barthe, G. Guennebaud, M.P. Cani, D. Rhomer and B. Wyvill. "Déformation de la peau d'un personnage avec prise en compte des contacts", Revue Electronique Francophone d'Informatique Graphique, Prix du Meilleur Papier AFIG/EGFR.

Mediation: Large public and scholars

• "De la sphère à l’animation de personnages virtuels : Pour un Pli", 1024 – Bulletin de la société informatique de France, HS1, pages 93-95, February 2015. All informations here

• Fonctions, formes 3D, assemblages et animation: Intervention devant les membres du cercle de Mathématiques Sofia Kovaleskaïa à l'Institut de Mathématiques de Toulouse dans le cadre d'une journée CIMI. La présentation intitulée "Fonctions, formes 3D, assemblages et animation" s'adresse à un public d'élèves de première et terminale de bon niveau et vraiment intéressé par les mathématiques. Toulouse 2015. All informations here

• Pour un pli (For a fold): Conference for the large public on the illustration of mathematics taught in high school on recent skinning research results. Poitier 2014, Limoges 2013. All informations here

• Animation movies and 3D video games: from practical to theoretical: Illustration with implicit surfaces and composition operators of the animation of a 3D object defined using middle school mathematics. Scholars in the academy of Toulouse 2012 and 2013. All informations here

Press & Visibility

• 16/11/2016 - RADI 2016: We have been invited to present the "Implicit Skinning" at the "Rencontres Animation Développement Innovation" (RADI 2016) in Angoulême.

• 27/02/2015 - Seminar at Collège de France during Marie-Paule's Cani lecture series.

• 28/10/2014 - Elastic Implicit Skinning - Views of the online Video: More than 5.700 views on Vimeo in less than 5 days !

• 28/10/2014 - Oline Computer Graphics Press: The Elastic Implicit Skinning in CG Press.

• 26/10/2014 - Implicit Skinning - Views of the online Video: More than 25.000 views on Vimeo and more than 120.000 views on Youtube. One of the most seen research Siggraph video.

• 11/09/2014 - CNRS Activity Report 2013: Researches on Implicit Skinning are presented in the CNRS Activity Report 2013 (page 46).