From pixels to people : recovering location, shape and pose of humans in images

Humans are at the centre of a significant amount of research in computer vision. Endowing machines with the ability to perceive people from visual data is an immense scientific challenge with a high degree of direct practical relevance. Success in automatic perception can be measured at different levels of abstraction, and this will depend on which intelligent behaviour we are trying to replicate: the ability to localise persons in an image or in the environment, understanding how persons are moving at the skeleton and at the surface level, interpreting their interactions with the environment including with other people, and perhaps even anticipating future actions. In this thesis we tackle different sub-problems of the broad research area referred to as "looking at people", aiming to perceive humans in images at different levels of granularity. We start with bounding box-level pedestrian detection: We present a retrospective analysis of methods published in the decade preceding our work, identifying various strands of research that have advanced the state of the art. With quantitative exper- iments, we demonstrate the critical role of developing better feature representations and having the right training distribution. We then contribute two methods based on the insights derived from our analysis: one that combines the strongest aspects of past detectors and another that focuses purely on learning representations. The latter method outperforms more complicated approaches, especially those based on hand- crafted features. We conclude our work on pedestrian detection with a forward-looking analysis that maps out potential avenues for future research. We then turn to pixel-level methods: Perceiving humans requires us to both separate them precisely from the background and identify their surroundings. To this end, we introduce Cityscapes, a large-scale dataset for street scene understanding. This has since established itself as a go-to benchmark for segmentation and detection. We additionally develop methods that relax the requirement for expensive pixel-level annotations, focusing on the task of boundary detection, i.e. identifying the outlines of relevant objects and surfaces. Next, we make the jump from pixels to 3D surfaces, from localising and labelling to fine-grained spatial understanding. We contribute a method for recovering 3D human shape and pose, which marries the advantages of learning-based and model- based approaches. We conclude the thesis with a detailed discussion of benchmarking practices in computer vision. Among other things, we argue that the design of future datasets should be driven by the general goal of combinatorial robustness besides task-specific considerations.Der Mensch steht im Zentrum vieler Forschungsanstrengungen im Bereich des maschinellen Sehens. Es ist eine immense wissenschaftliche Herausforderung mit hohem unmittelbarem Praxisbezug, Maschinen mit der Fähigkeit auszustatten, Menschen auf der Grundlage von visuellen Daten wahrzunehmen. Die automatische Wahrnehmung kann auf verschiedenen Abstraktionsebenen erfolgen. Dies hängt davon ab, welches intelligente Verhalten wir nachbilden wollen: die Fähigkeit, Personen auf der Bildfläche oder im 3D-Raum zu lokalisieren, die Bewegungen von Körperteilen und Körperoberflächen zu erfassen, Interaktionen einer Person mit ihrer Umgebung einschließlich mit anderen Menschen zu deuten, und vielleicht sogar zukünftige Handlungen zu antizipieren. In dieser Arbeit beschäftigen wir uns mit verschiedenen Teilproblemen die dem breiten Forschungsgebiet "Betrachten von Menschen" gehören. Beginnend mit der Fußgängererkennung präsentieren wir eine Analyse von Methoden, die im Jahrzehnt vor unserem Ausgangspunkt veröffentlicht wurden, und identifizieren dabei verschiedene Forschungsstränge, die den Stand der Technik vorangetrieben haben. Unsere quantitativen Experimente zeigen die entscheidende Rolle sowohl der Entwicklung besserer Bildmerkmale als auch der Trainingsdatenverteilung. Anschließend tragen wir zwei Methoden bei, die auf den Erkenntnissen unserer Analyse basieren: eine Methode, die die stärksten Aspekte vergangener Detektoren kombiniert, eine andere, die sich im Wesentlichen auf das Lernen von Bildmerkmalen konzentriert. Letztere übertrifft kompliziertere Methoden, insbesondere solche, die auf handgefertigten Bildmerkmalen basieren. Wir schließen unsere Arbeit zur Fußgängererkennung mit einer vorausschauenden Analyse ab, die mögliche Wege für die zukünftige Forschung aufzeigt. Anschließend wenden wir uns Methoden zu, die Entscheidungen auf Pixelebene betreffen. Um Menschen wahrzunehmen, müssen wir diese sowohl praezise vom Hintergrund trennen als auch ihre Umgebung verstehen. Zu diesem Zweck führen wir Cityscapes ein, einen umfangreichen Datensatz zum Verständnis von Straßenszenen. Dieser hat sich seitdem als Standardbenchmark für Segmentierung und Erkennung etabliert. Darüber hinaus entwickeln wir Methoden, die die Notwendigkeit teurer Annotationen auf Pixelebene reduzieren. Wir konzentrieren uns hierbei auf die Aufgabe der Umgrenzungserkennung, d. h. das Erkennen der Umrisse relevanter Objekte und Oberflächen. Als nächstes machen wir den Sprung von Pixeln zu 3D-Oberflächen, vom Lokalisieren und Beschriften zum präzisen räumlichen Verständnis. Wir tragen eine Methode zur Schätzung der 3D-Körperoberfläche sowie der 3D-Körperpose bei, die die Vorteile von lernbasierten und modellbasierten Ansätzen vereint. Wir schließen die Arbeit mit einer ausführlichen Diskussion von Evaluationspraktiken im maschinellen Sehen ab. Unter anderem argumentieren wir, dass der Entwurf zukünftiger Datensätze neben aufgabenspezifischen Überlegungen vom allgemeinen Ziel der kombinatorischen Robustheit bestimmt werden sollte

NEVIS'22: A Stream of 100 Tasks Sampled from 30 Years of Computer Vision Research

We introduce the Never Ending VIsual-classification Stream (NEVIS'22), a benchmark consisting of a stream of over 100 visual classification tasks, sorted chronologically and extracted from papers sampled uniformly from computer vision proceedings spanning the last three decades. The resulting stream reflects what the research community thought was meaningful at any point in time. Despite being limited to classification, the resulting stream has a rich diversity of tasks from OCR, to texture analysis, crowd counting, scene recognition, and so forth. The diversity is also reflected in the wide range of dataset sizes, spanning over four orders of magnitude. Overall, NEVIS'22 poses an unprecedented challenge for current sequential learning approaches due to the scale and diversity of tasks, yet with a low entry barrier as it is limited to a single modality and each task is a classical supervised learning problem. Moreover, we provide a reference implementation including strong baselines and a simple evaluation protocol to compare methods in terms of their trade-off between accuracy and compute. We hope that NEVIS'22 can be useful to researchers working on continual learning, meta-learning, AutoML and more generally sequential learning, and help these communities join forces towards more robust and efficient models that efficiently adapt to a never ending stream of data. Implementations have been made available at https://github.com/deepmind/dm_nevis

Simultaneous motion detection and background reconstruction with a conditional mixed-state markov random field

In this work we present a new way of simultaneously solving the problems of motion detection and background image reconstruction. An accurate estimation of the background is only possible if we locate the moving objects. Meanwhile, a correct motion detection is achieved if we have a good available background model. The key of our joint approach is to define a single random process that can take two types of values, instead of defining two different processes, one symbolic (motion detection) and one numeric (background intensity estimation). It thus allows to exploit the (spatio-temporal) interaction between a decision (motion detection) and an estimation (intensity reconstruction) problem. Consequently, the meaning of solving both tasks jointly, is to obtain a single optimal estimate of such a process. The intrinsic interaction and simultaneity between both problems is shown to be better modeled within the so-called mixed-state statistical framework, which is extended here to account for symbolic states and conditional random fields. Experiments on real sequences and comparisons with existing motion detection methods support our proposal. Further implications for video sequence inpainting will be also discussed. © 2011 Springer Science+Business Media, LLC.postprin

Deep Neural Networks and Data for Automated Driving

This open access book brings together the latest developments from industry and research on automated driving and artificial intelligence. Environment perception for highly automated driving heavily employs deep neural networks, facing many challenges. How much data do we need for training and testing? How to use synthetic data to save labeling costs for training? How do we increase robustness and decrease memory usage? For inevitably poor conditions: How do we know that the network is uncertain about its decisions? Can we understand a bit more about what actually happens inside neural networks? This leads to a very practical problem particularly for DNNs employed in automated driving: What are useful validation techniques and how about safety? This book unites the views from both academia and industry, where computer vision and machine learning meet environment perception for highly automated driving. Naturally, aspects of data, robustness, uncertainty quantification, and, last but not least, safety are at the core of it. This book is unique: In its first part, an extended survey of all the relevant aspects is provided. The second part contains the detailed technical elaboration of the various questions mentioned above

The Quadric Reference Surface: Theory and Applications

The conceptual component of this work is about "reference surfaces'' which are the dual of reference frames often used for shape representation purposes. The theoretical component of this work involves the question of whether one can find a unique (and simple) mapping that aligns two arbitrary perspective views of an opaque textured quadric surface in 3D, given (i) few corresponding points in the two views, or (ii) the outline conic of the surface in one view (only) and few corresponding points in the two views. The practical component of this work is concerned with applying the theoretical results as tools for the task of achieving full correspondence between views of arbitrary objects

Digital Image Access & Retrieval

The 33th Annual Clinic on Library Applications of Data Processing, held at the University of Illinois at Urbana-Champaign in March of 1996, addressed the theme of "Digital Image Access & Retrieval." The papers from this conference cover a wide range of topics concerning digital imaging technology for visual resource collections. Papers covered three general areas: (1) systems, planning, and implementation; (2) automatic and semi-automatic indexing; and (3) preservation with the bulk of the conference focusing on indexing and retrieval.published or submitted for publicatio