Two Interviews with renown Datasets Researchers

Authors: Nacho Reimat, (CWI, Amsterdam, The Netherlands), 
                    Pierre-Etienne Martin, (Max Planck Institute for Evolutionary Anthropology, Germany)

Editors: Maria Torres Vega (Ghent University, Belgium), 
                  Mihai Gabriel Constantin (University Politehnica of Bucharest, Romania), 
Karel Fliegel (Czech Technical University in Prague, Czech Republic)

This issue of the Dataset Column provides two interviews with the researchers responsible for novel datasets of recent years. In particular, we first interview Nacho Reimat (, the scientific programmer responsible for the CWIPC-SXR, one of the first datasets on dynamic, interactive volumetric media. Second, we interview Pierre-Etienne Martin (, responsible for contributions to datasets in the area of sports and culture.  

The two interviewees were asked about their contribution to the dataset research, their interests, challenges, and the future.  We would like to thank both Nacho and Pierre-Etienne for their agreement to contribute to our column. 

Nacho Reimat, Scientific Programmer at the Distributed and Interactive Systems group at the CWI, Amsterdam, The Netherlands

Short bio: Ignacio Reimat is currently an R&D Engineer at Centrum Wiskunde & Informatica (CWI) in Amsterdam. He received the B.S. degree in Audiovisual Systems Engineering of Telecommunications at Universitat Politecnica de Catalunya in 2016 and the M.S degree in Innovation and Research in Informatics – Computer Graphics and Virtual Reality at Universitat Politecnica de Catalunya in 2020. His current research interests are 3D graphics, volumetric capturing, 3d reconstruction, point clouds, social Virtual Reality and real-time communications.

Could you provide a small summary of your contribution to the dataset research?

We have released the CWI Point Cloud Social XR Dataset [1], a dynamic point cloud dataset that depicts humans interacting in social XR settings. In particular, using commodity hardware we captured audio-visual data (RGB + Depth + Infrared + synchronized Audio) for a total of 45 unique sequences of people performing scripted actions [2]. The screenplays for the human actors were devised so as to simulate a variety of common use cases in social XR, namely, (i) Education and training, (ii) Healthcare, (iii) communication and social interaction, and (iv) Performance and sports. Moreover, diversity in gender, age, ethnicities, materials, textures and colours were additionally considered. As part of our release, we provide annotated raw material, resulting point cloud sequences, and an auxiliary software toolbox to acquire, process, encode, and visualize data, suitable for real-time applications.

Sample frames from the point cloud sequences released with the CWIPC-SXR dataset.

Why did you get interested in datasets research?

Real-time, immersive telecommunication systems are quickly becoming a reality, thanks to the advances in the acquisition, transmission, and rendering technologies. Point clouds in particular serve as a promising representation in these types of systems, offering photorealistic rendering capabilities with low complexity. Further development of transmission, coding, and quality evaluation algorithms, though, is currently hindered by the lack of publicly available datasets that represent realistic scenarios of remote communication between people in real-time. So we are trying to fill this gap. 

What is the most challenging aspect of datasets research?

In our case, because point clouds are a relatively new format, the most challenging part has been developing the technology to generate them. Our dataset is generated from several cameras, which need to be calibrated and synchronized in order to merge the views successfully. Apart from that, if you are releasing a large dataset, you also need to deal with other challenges like data hosting and maintenance, but even more important, find the way to distribute the data in a way that is suitable for different target users. Because we are not releasing just point clouds but also the raw data, there may be people interested in the raw videos, or in particular point clouds, and they do not want to download the full 1.6TB of data. And going even further, because of the novelty of the point cloud format, there is also a lack of tools to re-capture, playback or modify this type of data. That’s why, together with the dataset, we also released our point cloud auxiliary toolbox of software utilities built on top of the Point Cloud Library, which allows for alignment and processing of point clouds, as well as real-time capturing, encoding, transmission, and rendering.

How do you see the future of datasets research?

Open datasets are an essential part of science since they allow for comparison and reproducibility. The major problem is that creating datasets is difficult and expensive, requiring a big investment from research groups. In order to ensure that relevant datasets keep on being created, we need a push including: scientific venues for the publication and discussion of datasets (like the dataset track at the Multimedia Systems conference, which started more than a decade ago), investment from funding agencies and organizations identifying the datasets that the community will need in the future, and collaboration between labs to share the effort.

What are your future plans for your research?

We are very happy with the first version of the dataset since it provides a good starting point and was a source of learning. Still, there is room for improvements, so now that we have a full capturing system (together with the auxiliary tools), we would like to extend the dataset and refine the tools. The community still needs more datasets of volumetric video to further advance the research on alignment, post-processing, compression, delivery, and rendering. Apart from the dataset, the Distributed and Interactive Systems ( group from CWI is working on volumetric video conferencing, developing a Social VR pipeline for enabling users to more naturally communicate and interact. Recently, we deployed a solution for visiting museums remotely together with friends and family members (, and next October we will start two EU-funded projects on this topic.   

Pierre-Etienne Martin, Postdoctoral Researcher & Tech Development Coordinator, Max Planck Institute for Evolutionary Anthropology, Department of Comparative Cultural Psychology, Leipzig, Germany

Short Bio: Pierre-Etienne Martin is currently a Postdoctoral researcher at the Max Planck Institute. He received his M.S. degree in 2017 from the University of Bordeaux, the Pázmány Péter Catholic University and the Autonomous University of Madrid via the Image Processing and Computer vision Erasmus Master program. He obtained his PhD, labelled European, from the University of Bordeaux in 2020, supervised by Jenny Benois-Pineau and Renaud Péteri, on the topic of video detection and classification by means of Convolutional Neural Networks. His current research interests include among others Artificial Intelligence, Machine Learning and Computer Vision.

Could you provide a small summary of your contribution to the dataset research?

In 2017, I started my PhD thesis which focuses on movement analysis in sports. The aim of this research project, so-called CRIPS (ComputeR vIsion for Sports Performance – see ), is to improve the training experience of the athletes. Our team decided to focus on Table Tennis, and it is with the collaboration of the Sports Faculty of the University of Bordeaux, STAPS, that our first contribution came to be: the TTStroke-21 dataset [3]. This dataset gathers recordings of table tennis games at high resolution and 120 frames per second. The players and annotators are both from the STAPS. The annotation platform was designed by students from the LaBRI – University of Bordeaux, and the MIA from the University of la Rochelle. Coordination for recording the videos and doing the annotation was performed by my supervisors and myself.

In 2019, and until now, the TTStroke-21 is used to propose the Sports Task at the Multimedia Evaluation benchmark – MediaEval [4]. The goal is to segment and classify table tennis strokes from videos.

TTStrokes-21 sample images

Since 2021, I have joined the MPI EVA institute and I now focus on elaborating datasets for the Comparative Cultural Psychology department (CCP). The data we are working on focuses on great apes and children. We aim at segmenting, identifying and tracking. 

Why did you get interested in datasets research?

Datasets research is the field where the application of computer vision tools is possible. In order to widen the range of applications, datasets with qualitative ground truth need to be offered by the scientific community. Only then, models can be developed to solve the problem raised by the dataset and finally be offered to the community. This has been the goal of the interdisciplinary CRISP project, through the collaboration of the sport and computer science community, for improving athlete performance.

It is also the aim of collaborative projects, such as MMLAB [5], which gathers many models and implementations trained on various datasets, in order to ease reproducibility, performance comparison and inference for applications.

What is the most challenging aspect of datasets research?

From my experience, when organizing the Sport task at the MediaEval workshop, the most challenging aspect of datasets research is to be able to provide qualitative data: from acquisition to annotation; and tools to process them: use, demonstration and evaluation. That is why, on the side of our task, we also provide a baseline which covers most of these aspects.

How do you see the future of datasets research?

I hope datasets research will transcend in order to have a general scheme for annotation and evaluation of datasets. I hope the different datasets could be used together for training multi-task models, and give the opportunity to share knowledge and features proper to each type of dataset. Finally, quantity has been a major criterion for dataset research, but quality should be more considered in order to improve state-of-the-art performance while keeping a sustainable way to conduct research.

What are your future plans for your research?

Within the CCP department at MPI, I hope to be able to build different types of datasets to put to best use what has been implemented in the computer vision field to psychology.

Relevant references:

  1. CWIPC-SXR dataset:
  2. I. Reimat, et al., “CWIPC-SXR: Point Cloud dynamic human dataset for Social XR. In Proceedings of the 12th ACM Multimedia Systems Conference (MMSys ’21). Association for Computing Machinery, New York, NY, USA, 300–306.
  3. TTStroke-21:
  4. Media-Eval:
  5. Open-MMLab:

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