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Vorträge

Deriving a Tongue Model from MRI Data

Talk
  • 20 February 2018 • 14:00 14:45
  • Alexander Hewer
  • Aquarium

The tongue plays a vital part in everyday life where we use it extensively during speech production. Due to this importance, we want to derive a parametric shape model of the tongue. This model enables us to reconstruct the full tongue shape from a sparse set of points, like for example motion capture data. Moreover, we can use such a model in simulations of the vocal tract to perform articulatory speech synthesis or to create animated virtual avatars. In my talk, I describe a framework for deriving such a model from MRI scans of the vocal tract. In particular, this framework uses image denoising and segmentation methods to produce a point cloud approximating the vocal tract surface. In this context, I will also discuss how palatal contacts of the tongue can be handled, i.e., situations where the tongue touches the palate and thus no tongue boundary is visible. Afterwards, template matching is used to derive a mesh representation of the tongue from this cloud. The acquired meshes are finally used to construct a multilinear model.

Organizers: Timo Bolkart

Nonstandard Analysis - The Comeback of Infinitesimals

Talk
  • 19 February 2018 • 11:00 12:15
  • Randolf Scholz
  • Tübingen,

The early Calculus of Newton and Leibniz made heavy use of infinitesimal quantities and flourished for over a hundred years until it was superseded by the more rigorous epsilon-delta formalism. It took until the 1950's for A. Robinson to find a proper way to construct a number system containing actual infinitesimals -- the Hyperreals *|R. This talk outlines their construction and possible applications in modern analysis.

Organizers: Philipp Hennig


  • Dr. Adam Spiers
  • MPI-IS Stuttgart, Heisenbergstr. 3, Room 2P4

This talk will focus on three topics of my research at Yale University, which centers on themes of human and robotic manipulation and haptic perception. My major research undertaking at Yale has involved running a quantitative study of daily upper-limb prosthesis use in unilateral amputees. This work aims to better understand the techniques employed by long-term users of artificial arms and hands in order to inform future prosthetic device design and therapeutic interventions. While past attempts to quantify prosthesis-use have implemented either behavioral questionnaires or observations of specific tasks in a structured laboratory settings, our approach involves participants completing many hours of self-selected household chores in their own homes while wearing a head mounted video camera. I will discuss how we have addressed the processing of such a large and unstructured data set, in addition to our current findings. Complementary to my work in prosthetics, I will also discuss my work on several novel robotic grippers which aim to enhance the grasping, manipulation and object identification capabilities of robotic systems. These grippers implement underactuated designs, machine learning approaches or variable friction surfaces to provide low-cost, model-free and easily reproducible solutions to what have been traditionally been considered complex problems in robotic manipulation, i.e. stable grasp acquisition, fast tactile object recognition and within-hand object manipulation. Finally, I will present a brief overview of my efforts designing and testing shape-changing haptic interfaces, a largely unexplored feedback modality that I believe has huge potential for discretely communicating information to people with and without sensory impairments. This technology has been implemented in a pedestrian navigation system and evaluated in a variety of scenarios, including a large scale immersive theatre production with visually impaired artistic collaborators and almost 100 participants.

Organizers: Katherine Kuchenbecker


  • Prof. Christian Wallraven
  • MPI-IS Stuttgart, Heisenbergstr. 3, Room 5H7

Already starting at birth, humans integrate information from several sensory modalities in order to form a representation of the environment - such as when a baby explores, manipulates, and interacts with objects. The combination of visual and touch information is one of the most fundamental sensory integration processes, as touch information (such as body-relative size, shape, texture, material, temperature, and weight) can easily be linked to the visual image, thereby providing a grounding for later visual-only recognition. Previous research on such integration processes has so far mainly focused on low-level object properties (such as curvature, or surface granularity) such that little is known on how the human actually forms a high-level multisensory representation of objects. Here, I will review research from our lab that investigates how the human brain processes shape using input from vision and touch. Using a large variety of novel, 3D-printed shapes we were able to show that touch is actually equally good at shape processing than vision, suggesting a common, multisensory representation of shape. We next conducted a series of imaging experiments (using anatomical, functional, and white-matter analyses) that chart the brain networks that process this shape representation. I will conclude the talk with a brief medley of other haptics-related research in the lab, including robot learning, braille, and haptic face recognition.

Organizers: Katherine Kuchenbecker


Maternal weight and metabolism related to fetal autonomic nervous system

IS Colloquium
  • 19 January 2018 • 11:00 12:00
  • Haliza Mat Husin
  • MPI-IS Stuttgart, Heisenbergstr. 3, Room 2P4

Organizers: Katherine Kuchenbecker


Appearance Modeling for 4D Multi-view Representations

Talk
  • 15 December 2017 • 12:00 12:45
  • Vagia Tsiminaki
  • PS Seminar Room (N3.022)

The emergence of multi-view capture systems has yield a tremendous amount of video sequences. The task of capturing spatio-temporal models from real world imagery (4D modeling) should arguably benefit from this enormous visual information. In order to achieve highly realistic representations both geometry and appearance need to be modeled in high precision. Yet, even with the great progress of the geometric modeling, the appearance aspect has not been fully explored and visual quality can still be improved. I will explain how we can optimally exploit the redundant visual information of the captured video sequences and provide a temporally coherent, super-resolved, view-independent appearance representation. I will further discuss how to exploit the interdependency of both geometry and appearance as separate modalities to enhance visual perception and finally how to decompose appearance representations into intrinsic components (shading & albedo) and super-resolve them jointly to allow for more realistic renderings.

Organizers: Despoina Paschalidou


Sum-Product Networks for Probabilistic Modeling

Talk
  • 06 December 2017 • 15:00 15:45
  • Robert Peharz
  • AGBS seminar room

Probabilistic modeling is the method of choice when it comes to reasoning under uncertainty. However, one of the main practical downsides of probabilistic models is that inference, i.e. the process of using the model to answer statistical queries, is notoriously hard in general. This led to a common folklore that probabilistic models which allow exact inference are necessarily simplistic and undermodel any practical task. In this talk, I will present sum-product networks (SPNs), a recently proposed architecture representing a rich and expressive class of probability distributions, which also allows exact and efficient computation of many inference tasks. I will discuss representational properties, inference routines and learning approaches in SPNs. Furthermore, I will provide some examples of practical applications using SPNs.


Reconstructing and Perceiving Humans in Motion

Talk
  • 30 November 2017 • 15:00
  • Dr. Gerard Pons-Moll

For man-machine interaction it is crucial to develop models of humans that look and move indistinguishably from real humans. Such virtual humans will be key for application areas such as computer vision, medicine and psychology, virtual and augmented reality and special effects in movies. Currently, digital models typically lack realistic soft tissue and clothing or require time-consuming manual editing of physical simulation parameters. Our hypothesis is that better and more realistic models of humans and clothing can be learned directly from real measurements coming from 4D scans, images and depth and inertial sensors. We combine statistical machine learning techniques and physics based simulation to create realistic models from data. We then use such models to extract information out of incomplete and noisy sensor data from monocular video, depth or IMUs. I will give an overview of a selection of projects conducted in Perceiving Systems in which we build realistic models of human pose, shape, soft-tissue and clothing. I will also present some of our recent work on 3D reconstruction of people models from monocular video, real-time fusion and online human body shape estimation from depth data and recovery of human pose in the wild from video and IMUs. I will conclude the talk outlining the next challenges in building digital humans and perceiving them from sensory data.

Organizers: Melanie Feldhofer


  • Professor Brent Gillespie
  • MPI-IS Stuttgart, Heisenbergstr.3, Werner-Köster-Hörsaal 2R 4 and broadcast

Relative to most robots and other machines, the human body is soft, its actuators compliant, and its control quite forgiving. But having a body that bends under load seems like a bad set-up for motor dexterity: the brain is faced with controlling more rather than fewer degrees of freedom. Undeniably, though, the soft body approach leads to superior solutions. Robots are putzes by comparison! While de-putzifying robots (perhaps by making them softer) is an endeavor I will discuss to some degree, in this talk I will focus on the design of robots intended to work cooperatively with humans, using physical interaction and haptic feedback in the axis of control. I will propose a backdrivable robot with forgiving control as a teammate for humans, with the aim of meeting pressing needs in rehabilitation robotics and semi-autonomous driving. In short, my lab is working to create alternatives to the domineering robot who wants complete control. Giving up complete control leads to “slacking” and loss of therapeutic benefit in rehabilitation and loss of vigilance and potential for disaster in driving. Cooperative or shared control is premised on the idea that two heads, especially two heads with complementary capabilities, are better than one. But the two heads must agree on a goal and a motor plan. How can one agent read the motor intent of another using only physical interaction signals? A few old-school control principles from biology and engineering to the rescue! One key is provided by von Holst and Mittelsteadt’s famous Reafference Principle, published in 1950 to describe how a hierarchically organized neural control system distinguishes what they called reafference from exafference—roughly: expected from unexpected. A second key is provided by Francis and Wonham’s Internal Model Principle, published in in 1976 and considered an enabler for the disk drive industry. If we extend the Reafference Principle with model-based control and use the Internal Model Principle to treat predictable exogenous (exafferent) signals, then we arrive at a theory that I will argue puts us into position to extract motor intent and thereby enable effective control sharing between humans and robots. To support my arguments I will present results from a series of experiments in which we asked human participants to move expected and unexpected loads, to track predictable and unpredictable reference signals, to exercise with self-assist and other-assist, and to share control over a simulated car with an automation system.

Organizers: Katherine Kuchenbecker


  • Christoph Mayer
  • S2 Seminar Room (S 2.014)

Variational image processing translates image processing tasks into optimisation problems. The practical success of this approach depends on the type of optimisation problem and on the properties of the ensuing algorithm. A recent breakthrough was to realise that old first-order optimisation algorithms based on operator splitting are particularly suited for modern data analysis problems. Operator splitting techniques decouple complex optimisation problems into many smaller and simpler sub-problems. In this talk I will revise the variational segmentation problem and a common family of algorithms to solve such optimisation problems. I will show that operator splitting leads to a divide-and-conquer strategy that allows to derive simple and massively parallel updates suitable for GPU implementations. The technique decouples the likelihood from the prior term and allows to use a data-driven model estimating the likelihood from data, using for example deep learning. Using a different decoupling strategy together with general consensus optimisation leads to fully distributed algorithms especially suitable for large-scale segmentation problems. Motivating applications are 3d yeast-cell reconstruction and segmentation of histology data.

Organizers: Benjamin Coors


Learning Complex Robot-Environment Interactions

Talk
  • 26 October 2017 • 11:00 12:15
  • Jens Kober
  • AMD meeting room

The acquisition and self-improvement of novel motor skills is among the most important problems in robotics. Reinforcement learning and imitation learning are two different but complimentary machine learning approaches commonly used for learning motor skills.

Organizers: Dieter Büchler