Andrei Zaharescu

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In this paper we revisit local feature detectors/descriptors developed for 2D images and extend them to the more general framework of scalar fields defined on 2D manifolds. We provide methods and tools to detect and describe features on surfaces equiped with scalar functions, such as photometric information. This is motivated by the growing need for(More)
This paper proposes a novel approach to anomalous behaviour detection in video. The approach is comprised of three key components. First, distributions of spatiotemporal oriented energy are used to model behaviour. This representation can capture a wide range of naturally occurring visual spacetime patterns and has not previously been applied to anomaly(More)
This paper addresses the problem of describing surfaces using local features and descriptors. While methods for the detection of interest points in images and their description based on local image features are very well understood, their extension to discrete manifolds has not been well investigated. We provide a methodological framework for analyzing(More)
In this paper, we address the problem of surface tracking in multiple camera environments and over time sequences. In order to fully track a surface undergoing significant deformations, we cast the problem as a mesh evolution over time. Such an evolution is driven by 3D displacement fields estimated between meshes recovered independently at different time(More)
Triangulated meshes have become ubiquitous discrete surface representations. In this paper, we address the problem of how to maintain the manifold properties of a surface while it undergoes strong deformations that may cause topological changes. We introduce a new self-intersection removal algorithm, TransforMesh, and propose a mesh evolution framework(More)
Most of the algorithms dealing with image based 3-D reconstruction involve the evolution of a surface based on a minimization criterion. The mesh parametrization, while allowing for an accurate surface representation, suffers from the inherent problems of not being able to reliably deal with selfintersections and topology changes. As a consequence, an(More)
In this paper we address the problem of building a class of robust factorization algorithms that solve for the shape and motion parameters with both affine (weak perspective) and perspective camera models. We introduce a Gaussian/uniform mixture model and its associated EM algorithm. This allows us to address parameter estimation within a data clustering(More)
Feature-based approaches have recently become very popular in computer vision and image analysis applications, and are becoming a promising direction in shape retrieval. SHREC’11 robust feature detection and description benchmark simulates the feature detection and description stages of feature-based shape retrieval algorithms. The benchmark tests the(More)
In this paper we propose a framework for piecewise mesh-based 3D reconstruction from a set of calibrated images. Most of the existing approaches consider all available images at once. However, this is not tractable with very large sets of cameras. Therefore, we use subsets of images and evolve parts of the surface corresponding to those images. Our main(More)
This paper presents a novel real-time multi-feature multi-scale codebook-based background subtraction algorithm, targeted for challenging surveillance environments. Our contribution is three-fold. First, we present an extension of the Codebook background model [4] that combines multiple features, such as intensity, colour and texture, in a principled way,(More)