Mohamed daoudi - Academia.edu (original) (raw)

Papers by Mohamed daoudi

Image and Vision Computing, 2014

3D Shape similarity from video is a challenging problem lying at the heart of many primary resear... more 3D Shape similarity from video is a challenging problem lying at the heart of many primary research areas in computer graphics and computer vision applications. In this paper, we address within a new framework the problem of 3D shape representation and shape similarity in human video sequences. Our shape representation is formulated using Extremal Human Curve (EHC) descriptor extracted from the body surface. It allows taking benefits from Riemannian geometry in the open curve shape space and therefore computing statistics on it. It also allows subject pose comparison regardless of geometrical transformations and elastic surface change. Shape similarity is performed by an efficient method which takes advantage of a compact EHC representation in open curve shape space and an elastic distance measure. Thanks to these main assets, several important exploitations of the human action analysis are performed: shape similarity computation, video sequence comparison, video segmentation, video clustering, summarization and motion retrieval.

Proceedings of the Ninth Acm International Conference, Oct 1, 2001

ABSTRACT With the increasing usage of 3D models, the need for efficient shape retrieval technique... more ABSTRACT With the increasing usage of 3D models, the need for efficient shape retrieval techniques became mandatory. In this chapter, several approaches for 3D retrieval and shape recognition are presented. Invariant descriptor issues for 3D static mesh are exposed, before addressing action and face recognition in 3D videos. Then classical 3D-search engine performance evaluation tools are thoroughly explained. Finally, examples of significant applications using 3D retrieval techniques are given.

2009 IEEE International Conference on Shape Modeling and Applications, 2009

In this paper, we present an evaluation method of 3D-mesh segmentation algorithms based on a grou... more In this paper, we present an evaluation method of 3D-mesh segmentation algorithms based on a ground-truth corpus. This corpus is composed of a set of 3D-models grouped in different classes (animals, furnitures, etc.) associated with several manual segmentations produced by human observers. We define a measure that quantifies the consistency between two segmentations of a 3D-model, whatever their granularity. Finally, we propose an objective quality score for the automatic evaluation of 3D-mesh segmentation algorithms based on these measures and on the ground-truth corpus. Thus the quality of segmentations obtained by automatic algorithms is evaluated in a quantitative way thanks to the quality score, and on an objective basis thanks to the groundtruth corpus. Our approach is illustrated through the evaluation of two recent 3D-mesh segmentation methods.

Journées Bases de Données Avancées, 2001

Lecture Notes in Computer Science, 2009

The main goal of this paper is to illustrate a geometric analysis of 3D facial shapes in presence... more The main goal of this paper is to illustrate a geometric analysis of 3D facial shapes in presence of varying facial expressions using the nose region. This approach consists of the following two main steps: (i) Each nasal surface is automatically denoised and preprocessed to result in an indexed collection of nasal curves. During this step one detects the tip of the nose and defines a surface distance function with that tip as the reference point. The level curves of this distance function are the desired facial curves. (ii) Comparisons between noses are based on optimal deformations from one to another. This, in turn, is based on optimal deformations of the corresponding nasal curves across surfaces under an elastic metric. The experimental results, generated using a subset of FRGC v2 dataset, demonstrate the success of the proposed framework in recognizing people under different facial expressions. The recognition rates obtained here exceed those for a baseline ICP algorithm on the same dataset.

Geomorphology, 2015

Permanent gullies are common features in many landscapes and quite often they represent the domin... more Permanent gullies are common features in many landscapes and quite often they represent the dominant soil erosion process. Once a gully has initiated, field evidence shows that gully channel formation and headcut migration rapidly occur. In order to prevent the undesired effects of gullying, there is a need to predict the places where new gullies might initiate. From detailed field measurements, studies have demonstrated strong inverse relationships between slope gradient of the soil surface (S) and drainage area (A) at the point of channel initiation across catchments in different climatic and morphological environments. Such slope-area thresholds (S-A) can be used to predict locations in the landscape where gullies might initiate. However, acquiring S-A requires detailed field investigations and accurate high resolution digital elevation data, which are usually difficult to acquire. To circumvent this issue, we propose a two-step method that uses published S-A thresholds and a logistic regression analysis (LR). S-A thresholds from the literature are used as proxies of field measurement. The method is calibrated and validated on a watershed, close to the town of Algiers, northern Algeria, where gully erosion affects most of the slopes. The gullies extend up to several kilometres in length and cover 16% of the study area. First we reconstruct the initiation areas of the existing gullies by applying S-A thresholds for similar environments. Then, using the initiation area map as the dependent variable with combinations of topographic and lithological predictor variables, we calibrate several LR models. It provides relevant results in terms of statistical reliability, prediction performance, and geomorphological significance. This method using S-A thresholds with data-driven assessment methods like LR proves to be efficient when applied to common spatial data and establishes a methodology that will allow similar studies to be undertaken elsewhere.

Lecture Notes in Computer Science, 2013

2010 20th International Conference on Pattern Recognition, 2010

In this paper, we propose a new approach for 3Dshape matching. This approach encloses an off-line... more In this paper, we propose a new approach for 3Dshape matching. This approach encloses an off-line step and an on-line step. In the off-line one, an alphabet, of which any shape can be composed, is constructed. First, 3D-objects are subdivided into a set of 3D-parts. The subdivision consists to extract from each object a set of feature points with associated curves. Then the whole set of 3D-parts is clustered into different classes from a semantic point of view. After that, each class is modeled by a Hidden Markov Model (HMM). The HMM, which represents a character in the alphabet, is trained using the set of curves corresponding to the class parts. Hence, any 3D-object can be represented by a set of characters. The on-line step consists to compare the set of characters representing the 3D-object query and that of each object in the given dataset. The experimental results obtained on the TOSCA dataset show that the system efficiently performs in retrieving similar 3Dmodels.

3D Object Processing, 2008

Page 1. 3 3D Indexing and Retrieval Stefano Berretti, Mohamed Daoudi, Alberto Del Bimbo, Tarik Fi... more Page 1. 3 3D Indexing and Retrieval Stefano Berretti, Mohamed Daoudi, Alberto Del Bimbo, Tarik Filali Ansary, Pietro Pala, Julien Tierny, Jean-Phillippe Vandeborre 3.1 Introduction This chapter introduces the problem of 3D ...

Third International Symposium on 3D Data Processing, Visualization, and Transmission (3DPVT'06), 2006

In this paper, we propose a method for 3D-model retrieval from one or more photos. This method pr... more In this paper, we propose a method for 3D-model retrieval from one or more photos. This method provides an "optimal" selection of 2D views to represent a 3D-model, and a probabilistic Bayesian method for 3D-model retrieval from realistic photos and sketches using these views. The characteristic view selection algorithm is based on an adaptive clustering algorithm and uses statistical model distribution scores to select the optimal number of views. We also introduce a Bayesian approach to score the probability of correspondence between the queries and the 3D-models. We present our results on the Princeton 3D Shape Benchmark database (1814 3D-models) and 50 photos (real photographs, sketches, synthesised images). A practical on-line 3D-model retrieval system based on our approach is available on the web to asset our results [1].

Procedia - Social and Behavioral Sciences, 2012

The education of Islamic finance has witnessed a drastic increase in different regions of the wor... more The education of Islamic finance has witnessed a drastic increase in different regions of the world over the last few years. This paper proposes to study the geo-educational dynamics of Islamic finance, i.e. the relationship between educational space and power. In this geo-educational rivalry some interesting facts are coming out. For instance Britain is outpacing motherhood countries of Islamic finance; in terms of the number of programs provided by UK higher education institutions. Malaysia, on t he other hand, is striving hard to consolidate its position to become an educational hub for Islamic finance. What does this dynamism tell us about the current and future cartography of Islamic finance education? Which countries and/or regions are going to take a lead? What sort of realities might develop at Universities, Departments and other higher educational institutions? Finally what sort of implications will these developments have upon the floats of Islamic finance discipline?

Three dimensional object recognition techniques have been studied extensively by the computer vis... more Three dimensional object recognition techniques have been studied extensively by the computer vision community. Many methods have been developed for 3D object recognition. Some of them are based on aspect graphs , extended Gaussian images , superquadrics , spin images , and geometric hashing . In this paper we give a new algorithm to segment a surface into plan facet's using the normal vector information on surface. In a second step new affine invariants descriptors for surface (and Objet 3D) are presented using differential geometry. The proposed recognition algorithm will be used in an indexing system for 3D meshs retrevial via interactive web windows.

Journal of Mathematical Imaging and Vision, 2009

This paper studies the problem of analyzing variability in shapes of facial surfaces using a Riem... more This paper studies the problem of analyzing variability in shapes of facial surfaces using a Riemannian framework, a fundamental approach that allows for joint matchings, comparisons, and deformations of faces under a chosen metric. The starting point is to impose a curvilinear coordinate system, named the Darcyan coordinate system, on facial surfaces; it is based on the level curves of the surface distance function measured from the tip of the nose. Each facial surface is now represented as an indexed collection of these level curves. The task of finding optimal deformations, or geodesic paths, between facial surfaces reduces to that of finding geodesics between level curves, which is accomplished using the theory of elastic shape analysis of 3D curves. Elastic framework allows for nonlinear matching between curves and between points across curves. The resulting geodesics provide optimal elastic deformations between faces and an elastic metric for comparing facial shapes. We demonstrate this idea using examples from FSU face database.

IEEE Transactions on Pattern Analysis and Machine Intelligence, 2000

We study shapes of facial surfaces for the purpose of face recognition. The main idea is to 1) re... more We study shapes of facial surfaces for the purpose of face recognition. The main idea is to 1) represent surfaces by unions of level curves, called facial curves, of the depth function and 2) compare shapes of surfaces implicitly using shapes of facial curves. The latter is performed using a differential geometric approach that computes geodesic lengths between closed curves on a shape manifold. These ideas are demonstrated using a nearest-neighbor classifier on two 3D face databases: Florida State University and Notre Dame, highlighting a good recognition performance.

IEEE Transactions on Multimedia, 2000

L'analyse des modèles 3D joue un rôle important dans de nombreuses applications. Dans cet article... more L'analyse des modèles 3D joue un rôle important dans de nombreuses applications. Dans cet article, nous présenterons une approche pour l'extraction de graphe de Reeb en définissant une nouvelle fonction d'application. Notre fonction d'application calcule une valeur réelle pour chaque sommet décrivant la structure topologique du modèle 3D. Nous effectuerons des contours discrets pour chaque sommet selon notre fonction d'application. Les changements topologiques sont détectés par l'analyse des contours discrets pour construire le graphe de Reeb. Notre fonction d'application possède les propriétés importantes : elle est invariante à des transformations rigides et non rigides, elle est insensible au bruit, elle est robuste à des petits changements topologiques et elle ne dépend pas de paramètres. En construisant les graphes de Reeb les propriétés de cette fonction montrent les parties significatives d'un modèle 3D. Nous limiterons les critères d'évaluation aux propriétés de notre fonction que nous allons comparer à celles utilisées dans l'état de l'art. Finalement, nous présenterons les graphes de Reeb extraits sur différents modèles 3D possédant de différentes positions.

This paper presents a Bayesian-based method for classifying 3D objects into a set of predetermine... more This paper presents a Bayesian-based method for classifying 3D objects into a set of predetermined object classes. The basic idea is to determine a set of most similar threedimensional objects. The three-dimensional models have to consider spatial properties such as shape. We use curvature as an intuitive and powerful similarity index for three-dimensional objects which consists of a histogram of the principal curvatures of each face of the mesh. An experimental evaluation demonstrates the satisfactory performance of our approach on a fifty three-dimensional models database.