Dr. Faniry H. Razafindrazaka

Freie Universität Berlin
AG Mathematical Geometry Processing
Arnimallee 6 — Room 110
D-14195 Berlin, Germany

Tel.: +49(30)83875860
Fax: +49(30)83875869


Faniry dot Razafi at fu-berlin dot de

faniry dot razafindrazaka at charite dot de

News

23.02.2017, I got a paper accepted at Geometric Modelling and Processing 2017.

01.09.2016, I will start a PostDoc at the Biofluidmechanic group Charite Berlin.

16.06.2016, I will be part of the local organizator of the International Geometry Summit in Berlin 2016.

11.04.2016, An implementation of the perfect matching quad layout on quadrilateral meshes is now online here.

23.02.2016, My PhD thesis is now avalaible online via the Dissertation online publication of Freie universität Berlin. It can be accessed here.

09.02.2016, I successfully defended my PhD thesis, Quad Layout Generation and Symmetric Tilings of Closed Surfaces with the honorable mention "summa cum laude".

Current Projects
  • BMBF VIP+ - Decision Support Software for the Therapy Planning of a Mitral Valve Intervention

    Bio Fluid Mechanic Lab Berlin, Since September 2016

    This project concerns the development of 3D visualization tools to speed up the segmentation of mitral valve MRI as well as Echo image data for clinical application. A valid pre-operative decision of a given patient is crucial for a successful surgical intervention. Mitral valve is a part of the heart which hard to model such that traditional segmentation software struggle to find the right geometry without intensive user manipulation. We will develop a standalone software based on shape matching, deformation and optimization to improve mitral valve therapy planning.

  • ECMath - Boundary-Sensitive Hodge Decompositions for the Analysis of Wall Shear Stress in Blood Vessels and Aorta

    Bio Fluid Mechanic Lab Berlin, Freie Universität Berlin, Since March 2017

    Based on novel results for smooth and discrete Hodge-type decompositions on manifolds with boundary, this project aims to incorporate discrete boundary-sensitive Hodge decompositions as a central tool for the analysis of blood flow and parameterization of blood vessels. These decompositions provide the following two substantial improvements over existing methods: First, they are able to distinguish harmonic blood ow arising from boundary in- and out ow from harmonic circulations induced by the interior topology of the geometry. Second, they guarantee a theoretically sound linkage of certain fields with controlled boundary behaviour to cohomological quantities of the geometry, which is the essential|and still missing|ingredient for the creation of periods to ensure global matching of parameter lines in modern parameterization techniques.

  • Publications
  • Optimal Base Complexes for Quadrilateral Meshes

    Faniry H. Razafindrazaka, Konrad Polthier

    CAGD 2017, Geometric Modelling and Processing, Xiamen 2017.

    [Pdf],[Url],[Demo].

  • Perfect Matching Quad Layouts for Manifold Meshes

    Faniry H. Razafindrazaka, Ulrich Reitebuch, Konrad Polthier

    Computer Graphics Forum, Symposium on Geometry Processing, Gratz 2015.

    [Pdf],[Url],[Appendix],[Models],[BibTex].

  • Realization of Regular Maps of Large Genus

    Faniry H. Razafindrazaka, Konrad Polthier

    Topological and Statistical Methods for Complex Data, pp 239-252, Image Selected as the Cover of the Proceedings, Springer Berlin Heidelberg, 2015.

    [Pdf],[Url],[BibTex].

  • Regular Surfaces and Regular Maps

    Faniry H. Razafindrazaka, Konrad Polthier

    Proceedings of Bridges 2014, Tessellations Publishing, Page 225-234, Image Selected as the Cover of the Proceedings,.

    [Pdf],[BibTex].
  • Optimization of Mesh Parameterizations

    Faniry H. Razafindrazaka, Ulrich Reitebuch, Konrad Polthier

    Poster presentation, 1st Prize, at Curves and Surfaces 2014, Paris.

    [Abstract].

  • The 6-ring

    Faniry H. Razafindrazaka, Konrad Polthier

    Proceedings of Bridges 2013, Tessellations Publishing, Page 279-286.

    [Pdf],[BibTex].
  • Regular Map Smoothing

    Faniry H. Razafindrazaka, Konrad Polthier

    IMAGEN-A, Publishing House of the University of Seville, Volume 3, Number 5, DGCI 2013.

    [Pdf],[BibTex].
  • Thesis
  • Quad Layout Generation and Symmetric Tilings of Closed Surfaces

    Faniry H. Razafindrazaka,

    Ph.D thesis, Freie Universität Berlin, Germany 2016.

    [Diss].

    This thesis concerns two fundamental concepts in surface topology. The first part proposes a solution of the problem of generating an all quadrilateral patch layout on a given surface by a combinatorial graph optimization point of view. Mainly, finding a nice quad layout of a given surface is equivalent to solving a minimum weight perfect matching problem with additional quad guarantee constraints. The results are of high quality in terms of coarseness and alignment to important features of the geometry which can be used for wide range of applications such as hierarchical subdivision or high order surface fitting. The second part suggests an algorithm to symmetrically generate high genus surfaces suitable for space models of regular maps. It is based on a novel identification in hyperbolic space to derive directly the tubular neighborhood of the edge of a tiling from the hyperbolic representation followed by a spring relaxation procedure with intersection-free guarantee. We succeed to produce new embeddings of regular maps ranging from genus 5 to 85.

  • Visualization of High Genus Regular Maps

    Faniry H. Razafindrazaka,

    Master Thesis, Freie Universität Berlin, Germany 2012.

    [Pdf].

    We introduce a technique of embedding regular maps on surfaces of genus ≥ 2 with high symmetry. Each of these surfaces has the edge graph of an existing regular map as its medial axis. This enables the surfaces to inherit the symmetry of the regular maps. However, these surfaces may also self-intersect or degenerate if the medial axis is not smooth enough. We solve this problem by applying a force-directed algorithm on the medial axis without breaking the topology of the surface during the smoothing process. We do this interactively by turning the medial axis onto a control skeleton of the surface. The resulting shape has better symmetry than the starting one and the degeneracies are no longer present. For improved smoothness, we apply a polygon refinement scheme to the medial axis and a smoothing scheme on the final surface. We include a coloring scheme for each of the regular maps, anti-aliasing, smooth shading, Z-buffer, and transparency for high quality renderings.

  • Delaunay Triangulation Algorithm and Application to Terrain Generation

    Faniry H. Razafindrazaka,

    Postgraduate Diploma Thesis, African Institute for Mathematical Sciences (AIMS), Cape Town, South Africa 2009.

    [Pdf].

    We describe a randomized incremental algorithm for computing the Delaunay triangulation of a set of points and a recent technique of applying it to terrain generation. The algorithm is optimal, using a Directed Acyclic Graph (DAG)-based location structure for the incremental insertion which achieves an expected running time of O(n log n) and O(n) expected storage. The analysis of the expected storage is simplified, and the algorithm is implemented and tested. The implementation is done, in its integrality, with CGAL-Python which is fast and friendly, followed by numerical statistics on different distributions. The terrain generation technique is based on gaussian functions and the plotting is made with the Open Source software Blender 3D which is probably its first combination with CGAL-Python. A high quality rendering of three simple terrains is shown as a demonstration of the terrain generator.

  • Old Projects
  • Matheon Project F6 - Multilevel Methods on Manifold Meshes 2013-2014 [Link].

    This project addresses the strong needs for multilevel algorithms in industrial applications and in computer graphics where large surface meshes must be efficiently processed. Typical applications are solutions of PDEs on surfaces, surface optimization, and automatic mesh parametrization

  • Design Research Exchange 2012

    Faniry H. Razafindrazaka,

    [Report],[Link].

    The Design Research Exchange (DRX) is a non-profit residency program for researchers hosted by HENN. The DRX, initiated by Moritz Fleischmann (HENN Research Director) and Martin Henn (HENN Design Director), provides an open platform to unite experts from various fields. By exploring architectural topics of shared interest, the DRX promotes a multi-disciplinary discussion between academics and professionals. The DRX is envisioned as an environment for the advancement of fresh ideas and fertile ground for experimentation situated in-between academic research & architectural practice. The program is examining and advancing architectural techniques and methods, testing new technologies and materials, and informing our future built environment. Throughout the DRX, invited experts present public lectures and provide critical feedback and guidance. While working in small teams on the appointed topic, researchers have opportunities to join ongoing discussions, meetings, workshops, and lectures while gaining insight into ongoing HENN projects.

  • Research Industrial Project For Students 2010 (RIPS)

    Manuchehr Aminian, Liz Jimenez, Lothar Narins and Faniry H. Razafindrazaka,

    Acceleration mean curvature flow on the GPU, Mental Images/IPAM Los Angeles

    [Report]

    The Research in Industrial Projects for Students (RIPS) Program provides an opportunity for talented undergraduate students to work in teams on a real-world research projects proposed by sponsors from industry or the public sector. The student team, with support from their academic mentor and industry mentor, will research the problem and present their results, both orally and in writing, at the end of the program.

  • Teaching

  • Scientific Visualization course 2013/2014 (FU Berlin)

    Konrad Polthier, Konstantin Poelke and Faniry H. Razafindrazaka,

    [Link]

    Einführung in die Grundlagen der wissenschaftlichen Visualisierung und ihre Anwendungen in der Mathematik, Computergraphik und Naturwissenschaften.

      Grundlegende Datenstrukturen Flächentheorie von diskreten Gittern Visualisierungsverfahren, Animationen Subdivision, Wavelets, Hodge-Zerlegung 3D-Scanning, 3D-Druck, Flächenmodellierung Software und Anwendungsbeispiele.
  • Miscellanous
  • The Joint AIMS - Berlin Mathematical School Workshop on "Discrete Geometry and Visualization" [Link]

    In the presentations students and faculty will be introduced to recent developments of discrete (differential) geometry with applications to computer graphics and mathematical visualization. The courses and hands-on exercises are aimed at students with bachelor background but provide interesting material for faculty members as well. The workshop will include software tutorials, mathematical visualizations and animated film sequences.

  • Hochleistungsrechner

    Der Tagesspiegel

    [Link]

    Nein, er findet das alles nicht besonders anstrengend und abstrakt; all die Zahlen, Formeln, Funktionen, Grafiken. Mathematik, findet er, Mathematik bedeutet Freiheit. Ich muss keine tausend Seiten auswendig lernen, sondern nur den Grundgedanken verstehen, sagt Faniry Razafindrazaka, 23. Schon in der Schule hat er Mathe geliebt, bekam Bestnoten, damals in Madagaskar. Einige Lehrer rieten ihm: Mach etwas aus deinem Talent, studiere! Er h&Oulmrte auf sie und schrieb sich ein.


  • Last modified 30.03.2017, © 2017 Faniry Razafindrazaka