Ruben Wiersma, MSc

I recently started as a PhD candidate at the Computer Graphics and Visualization group. My interests include computer graphics, machine learning, storytelling (movies, experiences, books, etc.) and art. I will work on applications of computer graphics and machine learning for painting analysis under supervision of Prof. Dr. Elmar Eisemann and Prof. Dr. Joris Dik.

Personal webpage »

Master projects

I’m open to supervising Master students. Contact me (or one of my supervisors) if you’re interested in the following subjects:

  • Geometric Deep Learning: fundamentals and applications on meshes and point clouds
  • Graphics and Art: synthesis, analysis, rendering for paintings.
mark

PhD student
Room E6.420, Building 28
E-mail: <R.T.Wiersma_AT_tudelft.nl>

Publications

Publications in group repository »

CNNs on Surfaces using Rotation-Equivariant Features

ACM Transactions on Graphics 39(4) (SIGGRAPH 2020)
[preprint][code][project page][doi]

This paper is concerned with a fundamental problem in geometric deep learning that arises in the construction of convolutional neural networks on surfaces. Due to curvature, the transport of filter kernels on surfaces results in a rotational ambiguity, which prevents a uniform alignment of these kernels on the surface. We propose a network architecture for surfaces that consists of vector-valued, rotation-equivariant features. The equivariance property makes it possible to locally align features, which were computed in arbitrary coordinate systems, when aggregating features in a convolution layer. The resulting network is agnostic to the choices of coordinate systems for the tangent spaces on the surface. We implement our approach for triangle meshes. Based on circular harmonic functions, we introduce convolution filters for meshes that are rotation-equivariant at the discrete level. We evaluate the resulting networks on shape correspondence and shape classifications tasks and compare their performance to other approaches.

Revealing unique inscriptions of a Nazi collaborator in Doodencel 601 of the Oranjehotel

Heritage Science (July 2020)
[doi]

During the Second World War the German occupants of the Netherlands made ample use of the Scheveningen prison near The Hague, popularly nicknamed the Oranjehotel. One former death cell in this infamous prison (Doodencel 601) has been preserved in its original condition, showing wartime inscriptions on the cell walls. Interestingly, a small section of the wall has been given an additional plaster layer, presumably covering inscriptions. Here, we report on the visualization of this enigmatic text, which so far had escaped the reach of historians.