VUB Artificial Intelligence Lab

• Director: Prof. Dr. Luc Steels

• Expertise in– Complex Dynamical systems research– Artificial Life– Behavior-based robotics– Evolution of natural language– Cognitive modelling

Evolution of language

Language might be the key to intelligent behaviour. Research questions:

– What is needed in order to learn and produce linguistic utterances.

– How do humans conceptualise the world.– How does language evolve.

Language (and its components) is a complex dynamical system emerging from the interactions between individual language users.

Cognitive modelling

In order to investigate these issues, we use agent-based cognitive modelling

For example– Evolution of phonemes: vocal tract and auditory perception is

faithfully modelled, together with a phonetic memory which behaves as observed human behavior.

Talking Heads

• Large scale experiment started in 1999 to study the emergence and evolution of lexicons.

Agent based Combined perception and

language Lacked action and syntax.

Extending the Talking Heads

Talking Heads lacked two important components– Compositionality– Action

New experiment to solve– Stereo colour vision.– Learning in action space.– Associating perception, action,

conceptualisation and language.

VUB Electronics & Information Processing Lab

• Director: Prof. Dr. Jan Cornelis

• Expertise in– Compression of Images and Video – Multimedia Applications– Remote Sensing – Satellite Image Processing– Pattern Recognition – Classifier Models and

Evaluation/Applications– Medical Image Processing - Registration, Segmentation,

Analysis, Tele-Medicine– Applied Numerical Analysis and Inverse Problems – Theory and

Applications– Computer Vision – Computational Vision, Robotics and

Applications– Landmine Detection – Remote Sensing, Subsurface Imaging

Multimedia Applications• Image Compression

– JPEG, JPEG2000– Segmentation-based Coding– Volumetric Wavelet Coding (Medical, Remote Sensing)

• Video Compression– MPEG-x, H.26x– In-band Wavelet Video Coding

• Video Segmentation and Key Frame Extraction– MPEG-7

• Interactive Television• Synthetic/Natural Hybrid Coding

– MPEG-4: Facial Animation, Advanced Animation Framework (AFX), Mesh-Coding

• Memory Efficient HW/SW Implementations of Multimedia Systems

Frank

Sabine

Applied Numerical Analysis& Inverse Problems

• Applied Numerical Analysis – Subspace Algorithms– Nonlinear Optimization– Radial Basis Functions (RBF) Techniques

• Inverse Problems– Focus on Numerical Aspects (instead of more classical

functional analysis approach)– Multi-level Regularization

• Application Domains– Electrical Impedance Tomography (EIT)

… (General Medical, Dental Diagnosis, Subsurface Imaging)

– Tomographic Ground Penetrating Radar (GPR) Imaging… (Landmine Detection)

– Intra-Oral Digital Subtraction Radiography… (Hidden Caries Phenomenon)

Computer Vision• Computational Vision

– Inverse Problems for Scene Reconstruction

– Differential Equation Models in Vision

– Scale Space Theory for Image Analysis

– Model based image analysis/understanding

• Perception for Robotics– Active Visual Perception

– Visual Feedback for Control and Navigation

Computer Vision• Applications

– Measurement and interpretation of visual motion

– Motion and 3D shape from image sequences – Segmentation of Image/Motion – Perceptual Grouping– Face detection, tracking and animation– Visual tracking (surveillance)– Visual guidance/navigation of mobile robots

Vision Problems

Reconstruction– estimate parameters of external 3D world.

Segmentation– partition I(x,y,t) into subsets of separate objects.

Visual Control– visually guided locomotion and manipulation

Recognition– classes: face vs. non-face,– activities: gesture, expression.

Reconstruction

Computer vision address the inverse problem: given an image/multiple images, reconstruct the scene geometry, motion parameters, …

Single images adequate given knowledge of object class

Multiple images make the problem easier, but not trivial as corresponding points must be identified.

knowledge of object class

Original image

Detected line segments

Selected rooftops

All possible rooftop hypotheses

Line segment detection

MRF labeling

Building detectionMRF labeling

Perceptual grouping

Structure from Motion

Problem Statement: 3D line orientation (r) estimation from motion

Objective functional

PDE Model: vector-valued, reaction-diffusion

Propertiesdiffusion system coupled through the reaction term from 2D motion constraint, three processes evolve simultaneously; L-curve technique for estimating regularization parameter.

Experimental Results

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Multigrid Framework

Experimental Results

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Challenges in Reconstruction

Finding correspondences automatically

Optimal estimation of structure from n views under perspective projection

Models of reflectance and texture for natural materials and objects

Image Segmentation

Boundaries of image regions defined by a number of attributes Brightness/color

TextureMotiondepth

ApproachMultiscale region-based segmentation

Multiscale region-based segmentation

Motivation Partitioning of multivalued images into meaningful objects.

Main issues • Generation of a multiscale tower

using non-linear diffusion filtering..• Segmentation using gradient-driven

watersheds: Methods

• Hierarchical Segmentation Using Dynamics of Contours of Multiscale Color Gradient Watersheds: fine-to-coarse region merging using a saliency measure

• Hierarchical Labeling of Contours: Introduction of a causal Bayesian model to the scale space hierarchy of watersheds. Coarse-to-fine labeling using a MAP criterion based on a contour saliency measure and transition probabilities.

Segmentation examples

Temporal Segmentation: Tracking

Challenges in Segmentation

Interaction of multiple cues

Local measurements to global percepts

Interplay of image-driven and object model driven processing

Control

Visual feedback signal for control for tasks such as grasping and moving

Visual feedback for guiding locomotion Obstacle avoidance for a moving robot Lateral and longitudinal control of driving

Challenges in control

Delay in feedback loop due to visual processing

Hierarchies in sensory motor control

Open loop or closed loop Discrete planning or continuous control