Author Archives: andrea

Metric approaches to shape analysis

Deformable objects are ubiquitous in the world surrounding us, on all levels from micro to macro. The need to study such shapes and model their behavior arises in a wide spectrum of applications, ranging from medicine to security. In recent years, non-rigid shapes have attracted a growing interest, which has led to rapid development of the field, where state-of-the-art results from very different sciences – theoretical and numerical geometry, optimization, linear algebra, graph theory, machine learning and computer graphics, to mention a few – are applied to find solutions.

Maximally stable regions detected on shapes and different transformations

Maximally stable regions detected on shapes and different transformations

The purpose of the tutorial is to overview some state-of- the-art methods in the field of shape analysis through a consistent and rigorous mathematical framework.

The first part of the tutorial will focus on metric geometry approaches to shape analysis. Modeling shapes as metric spaces provides a common denominator for many problems in shape analysis. We will consider two archetype problems of similarity and correspondence.

Topics that will be covered include:

  • metric model of similarity and correspondence
  • invariance and isometry
  • rigid isometry and iterative closest point methods
  • multidimensional scaling and canonical forms
  • fast marching
  • Gromov-Hausdorff distances
  • self-similarity, symmetry and structure
  • correspondence and calculus of shapes

The second part of the tutorial will focus on diffusion geometry, arising from the geometric formulation of heat diffusion processes on manifolds. Diffusion geometry provides ways to construct robust global structures (metrics) and local structures (feature descriptors) for shape analysis.

Topics that will be covered include:

  • diffusion and heat operator
  • Laplace-Beltrami operator
  • diffusion distances
  • scale invariance and commute time distance
  • spectral shape disances
  • spectral symmetry
  • heat kernel signatures
  • bags of words
  • volumetric diffusion

Daniele Pezzatini will have a demo and an industrial exhibit session at ICME 2011

Daniele Pezzatini will present “A flexible system for multimedia management and publishing” (pdf) in the demo session and “A web system for ontology-based multimedia annotation, browsing and search” (pdf) in the Industrial Exhibit at the IEEE International Conference on Multimedia and Expo (ICME 2011) held in Barcelona, Spain from July 11 to 15, 2011.

ICME 2011, Barcelona

ICME 2011, Barcelona

Daniele, in the demo session, will demonstrate the IM3I (www.im3i.eu) platform, a system that provides a flexible approach for the management, annotation and publishing of collections of images and videos. The system is based on web services that allow automatic and manual annotation, retrieval, browsing and authoring of multimedia content.

At the industrial exhibit he will present a complete system for semantic and syntactic annotation, browsing and search of multimedia data, that is based on a service oriented architecture, with web-based interfaces developed following the Rich Internet Application paradigm.

Daniele Pezzatini

Daniele Pezzatini was born in Florence, Italy, in 21st of June 1985. He gradueted in computer engineering at University of Florence in April 2010. His thesis was on “Multi-touch environment for semantic search of multimedia contents”.

Daniele Pezzatini

Daniele Pezzatini

Currently he’s working at the Visual Information and Media Lab at Media Integration and Communication Center. His main research interests focus on natural interfaces and environments, web languages and usability.

Automatic region labeling on intercity urban scenarios

Current advanced vision systems aiming for activity recognition are strongly dependant on the locations of particular scenes, thereby restricting the semantic properties of the places where such events occur. Thus, a task for automatic and generic categorization of semantic regions is demanded in the field.

Automatic region labeling on intercity urban scenarios

Automatic region labeling on intercity urban scenarios

Carles Fernàndez Tena presents a method to perform automatic region labeling on intercity urban scenarios, based on the trajectories of pedestrians and vehicles observed by public webcams. As a result, the system divides the scenario into regions like crosswalks, sidewalks, roads, or waiting zones. Prior information is first modeled using a simple feature-based approach, and additional domain knowledge helps constraining spatial coherence to the results, by means of a MAP-MRF inference process. A progressive and thorough experimental validation will be presented, discussing a series of complementary steps that help enhancing the proposed framework.

Robust multiple structures estimation and architectural modelling

In this talk the engeineer Andrea Fusiello will tackle the problem of fitting multiple instances of a model to data corrupted by noise and outliers. A solution will be proposed based on random sampling and conceptual data representation. Each data point is represented with the characteristic function of the set of random models that fit that point.

Robust multiple structures estimation and architectural modelling

Robust multiple structures estimation and architectural modelling

A tailored agglomerative clustering, called J-linkage, is used to group points belonging to the same model. The method does not require prior specification of the number of models, nor it necessitates parameter tuning. Finally, I will touch upon an application of this technique to unsupervised reconstruction of architectural models in terms of high-level primitives.