Alex Bordignon

UFF - Universidade Federal Fluminense, Geometria, Adjunct

Followers

Following

Co-authors

Public Views

David Seamon

Kansas State University

Kathryn LaFevers Evans, Three Eagles

Pacifica Graduate Institute

Julio-César Mateus

Universidad de Lima

Achmad Supardi

President University

Juan Carlos Guerrero Bernal

Universidad del Rosario

Thulio Gomes

UFF - Universidade Federal Fluminense

Adrian Barbosa e Silva

Helen crewe

Nottingham Trent University

Celso Marquetti

Pontifícia Universidade Católica de São Paulo

Heather Booth

The Australian National University

InterestsView All (6)

Uploads

Papers by Alex Bordignon

EvolveDTree: Analyzing Student Dropout in Universities

2020 International Conference on Systems, Signals and Image Processing (IWSSIP)

Brazilian society suffers constant financial losses when higher education students disassociate f... more Brazilian society suffers constant financial losses when higher education students disassociate from universities without completing the degree program in which they were enrolled. This is especially true when the institutions are funded through public resources. In order to minimize evasion losses, socioeconomic policies and programs were created to assist and support actions seeking to maximize the number of students that graduate in a suitable program time. This work presents a methodology that aims to predict evasion by using machine learning. Our approach was able to classify student abandonment with an average f-score and accuracy results above 95%. Our approach combines a decision tree alongside a genetic algorithm and cluster stratified sampling. The results obtained show that students with a Grade Point Average (GPA) below 5.79 and that have been enrolled for more than a year require careful monitoring because they tend to exceed the program duration time or abandon it. Furthermore, approximately one-third of all identified dropouts students occurred in the first year.

Interpretable Concept Drift

Progress in Pattern Recognition, Image Analysis, Computer Vision, and Applications, 2021

Search time

Abstract. This work emerged from the following observation: usual search procedures for octrees s... more Abstract. This work emerged from the following observation: usual search procedures for octrees start from the root to retrieve the data stored at the leaves. But since the leaves are the farthest nodes to the root, why start from the root? With usual octree representations, there is no other way to access a leaf. However, hashed octrees allow direct access to any node, given its position in space and its depth in the octree. Search procedures take the position as an input, but the depth remains unknown. This work proposes to estimate the depth of an arbitrary node through a statistical optimization of the average cost of search procedures. Since the highest costs of these algorithms are obtained when starting from the root, this method improves on both the memory footprint by the use of hashed octrees, and execution time through the proposed optimization. Keywords: Octree. Hashing. Quadtree. Geometric Modelling. Data Structures. top down # leaves x 10 8

And Thomas Lewiner 1

Abstract. The definition of a good view of a 3D scene is highly subjective and strongly depends o... more Abstract. The definition of a good view of a 3D scene is highly subjective and strongly depends on both the scene content and the 3D application. Usually, camera placement is performed directly by the user, and that task may be laborious. Existing automatic virtual cameras guide the user by optimizing a single rule, e.g. maximizing the visible silhouette or the projected area. However, the use of a static pre-defined rule may fail in respecting the user’s subjective understanding of the scene. This work introduces intelligent design galleries, a learning approach for subjective problems such as the camera placement. The interaction of the user with a design gallery teaches a statistical learning machine. The trained machine can then imitate the user, either by pre-selecting good views or by automatically placing the camera. The learning process relies on a Support Vector Machines for classifying views from a collection of descriptors, ranging from 2D image quality to 3D features vis...

Download

Technical Section: Point-based rendering of implicit surfaces in R4

Computers and Graphics, Nov 1, 2013

We present a point-based algorithm for rendering implicit surfaces in R^4. Our algorithm combines... more We present a point-based algorithm for rendering implicit surfaces in R^4. Our algorithm combines a new method for approximating an implicit surface with points which uses interval arithmetic for topological robustness with a new 4D illumination model that together with a color transfer function enhances the visualization of a two-dimensional surface in four-dimensional space.

Point-based rendering of implicit surfaces in

Computers & Graphics, 2013

ABSTRACT We present a point-based algorithm for rendering implicit surfaces in R4. Our algorithm ... more ABSTRACT We present a point-based algorithm for rendering implicit surfaces in R4. Our algorithm combines a new method for approximating an implicit surface with points which uses interval arithmetic for topological robustness with a new 4D illumination model that together with a color transfer function enhances the visualization of a two-dimensional surface in four-dimensional space.

New method of seismofacies identification using machine learning over seismic attributes applied to salt stratifications

Brazilian Journal of Geophysics, 2021

ABSTRACT. Salt Evaporites may be grouped into three major seismic facies: Halite, High Velocity S... more ABSTRACT. Salt Evaporites may be grouped into three major seismic facies: Halite, High Velocity Salts (formed by anhydrite and gypsum) and Low Velocity Salts (formed mainly by carnallite, sylvite and tachyhydrite). However, the tachyhydrite mineral presents the biggest technical and financial concerns as it causes fluid loss during the salt drilling operation as observed in the Santos Basin, Brazilian Offshore, due to its high solubility. The correct facies identification allows adjusting the drilling parameters accordingly to the estimated salt type, minimizing operational problems and economic losses. In this article, we propose the use of selected seismic attributes from 2D sections combined with some of the most recent machine learning algorithms such as Uniform Manifold Approximation and Projection for Dimension Reduction (UMAP) and Hierarchical Density-Based Spatial Clustering of Applications with Noise (HDBSCAN), to identify stratifications within the salt layer and their cor...

Download

Identifying salt stratifications performing the machine learning approach over seismic attributes

Proceedings of the 16th International Congress of the Brazilian Geophysical Society&Expogef, 2019

Data Warehouse Educacional: Uma visão sobre a Evasão no Ensino Superior

Anais do Simpósio Brasileiro de Banco de Dados (SBBD)

A evasão mostra-se como um dos principais desafios das instituições de ensino. Nesse sentido, est... more A evasão mostra-se como um dos principais desafios das instituições de ensino. Nesse sentido, este trabalho apresenta a implementação de um Data Warehouse para análise de dados e auxílio à tomada de decisão em uma instituição de ensino superior do Brasil. O Data Warehouse apresentado permite visões integradas que auxiliam em análises de: 1) distribuição do coeficiente de desempenho dos alunos; 2) identificação dos perfis dos estudantes e 3) um dashboard sobre o rendimento dos alunos por localidade. Essas análises têm como propósito auxiliar a gestão acadêmica na identificação de padrões que acarretam na evasão e, desta forma, promover direcionamentos para medidas preventivas e, principalmente, expandir o uso deste banco de dados analítico para desenvolver novas soluções, como por exemplo, modelos preditivos.

Download

Minera��o Visual de Multiatributos S�smicos para Classifica��o de Multif�cies

Data Warehouse Educacional: Uma visão sobre a Evasão no Ensino Superior

Anais do Simpósio Brasileiro de Banco de Dados (SBBD)

Download

Data Warehouse Educacional: Uma visão sobre a Evasão no Ensino Superior

Anais do Simpósio Brasileiro de Banco de Dados (SBBD)

Download

NAVIER-STOKES EM GPU

An image-space algorithm for immersive views in 3-manifolds and orbifolds

The Visual Computer, 2014

ABSTRACT We describe the first image-space ray-tracing algorithm to generate interior views of fl... more ABSTRACT We describe the first image-space ray-tracing algorithm to generate interior views of flat or hyperbolic 3-manifolds, orbifolds, and similar polyhedral complexes. The complexity of our algorithm is linear in the number of echoes for a given number of polygons, compared to exponential complexity for the object-space algorithm chosen as standard.

Multi-attribute Seismic Cell Reservoir/Non-Reservoir Classiflcation with Kernel Based Methods

Kernel machines are recognized as an important class of artiflcial intelligence methods. Their us... more Kernel machines are recognized as an important class of artiflcial intelligence methods. Their use in geosciences applications have been increasing in recent years. In this paper we propose a new scheme to distinguish each seismic cell as reservoir or non-reservoir. For this, we use multi-attribute seismic and well data for the learning process. The method shows to be very promising

Download

Reconstrução Topológica Tridimensional de Objetos Geológicos em Bacias Marítimas Usando Dados Sísmicos 2D ou 3D: uma Ferramenta Exploratória e Explotatória de Hidrocarbonetos

The interplay between geophysics and geology is today one of the main challenges in reservoir cha... more The interplay between geophysics and geology is today one of the main challenges in reservoir characterization. In this paper we expose the ideia that by careful mathematical formulation and computer graphics tools it is possible to reconstruct 3D geological forms starting with seismic parameters. We reconstruct all the topological components of isosurfaces in subvoxel resolution starting with seismic parameters. Each isosurface component represents the boundary of a geobody. This type of reconstruction helps the modeler to understanding better the seismic information, the geobody spatial characteristics and make quantitative estimations such as reservoir volume.

Mineração Visual de Multiatributos Sísmicos para Classificação de Multifácies

10th International Congress of the Brazilian Geophysical Society & EXPOGEF 2007, Rio de Janeiro, Brazil, 19-23 November 2007, 2007

The understanding of large data clustering is a relevant problem in several areas of science and ... more The understanding of large data clustering is a relevant problem in several areas of science and engineering. Seismic signal are in general represented by large data sets. For petroleum geophysicists the choice of areas of interest is a demanding task. In this paper we introduce data mining visualizationtechniques, stellar coordinates and transfer functions, which easy the task of dealing visually

Reconstrução Topológica Tridimensional de Objetos Geológicos em Bacias Marítimas Usando Dados Sísmicos 2D ou 3D: uma Ferramenta Exploratória e Explotatória de Hidrocarbonetos

10th International Congress of the Brazilian Geophysical Society & EXPOGEF 2007, Rio de Janeiro, Brazil, 19-23 November 2007, 2007

Geometry super-resolution by example

Proceedings of SIBGRAPI 2009 - 22nd Brazilian Symposium on Computer Graphics and Image Processing, 2009

. Super-resolution of a scanned keyboard with a high-resolution scan of one of its keys: original... more

Download

Arch generated shear bands in granular systems

Physica A: Statistical Mechanics and its Applications, 2009

We propose an arch based model, on cubic and square lattices, to simulate the internal mobility o... more

EvolveDTree: Analyzing Student Dropout in Universities

2020 International Conference on Systems, Signals and Image Processing (IWSSIP)

Interpretable Concept Drift

Progress in Pattern Recognition, Image Analysis, Computer Vision, and Applications, 2021

Search time

And Thomas Lewiner 1

Download

Technical Section: Point-based rendering of implicit surfaces in R4

Computers and Graphics, Nov 1, 2013

Point-based rendering of implicit surfaces in

Computers & Graphics, 2013

New method of seismofacies identification using machine learning over seismic attributes applied to salt stratifications

Brazilian Journal of Geophysics, 2021

Download

Identifying salt stratifications performing the machine learning approach over seismic attributes

Proceedings of the 16th International Congress of the Brazilian Geophysical Society&Expogef, 2019

Data Warehouse Educacional: Uma visão sobre a Evasão no Ensino Superior

Anais do Simpósio Brasileiro de Banco de Dados (SBBD)

Download

Minera��o Visual de Multiatributos S�smicos para Classifica��o de Multif�cies

Data Warehouse Educacional: Uma visão sobre a Evasão no Ensino Superior

Anais do Simpósio Brasileiro de Banco de Dados (SBBD)

Download

Data Warehouse Educacional: Uma visão sobre a Evasão no Ensino Superior

Anais do Simpósio Brasileiro de Banco de Dados (SBBD)

Download

NAVIER-STOKES EM GPU

An image-space algorithm for immersive views in 3-manifolds and orbifolds

The Visual Computer, 2014

Multi-attribute Seismic Cell Reservoir/Non-Reservoir Classiflcation with Kernel Based Methods

Download

Reconstrução Topológica Tridimensional de Objetos Geológicos em Bacias Marítimas Usando Dados Sísmicos 2D ou 3D: uma Ferramenta Exploratória e Explotatória de Hidrocarbonetos

Mineração Visual de Multiatributos Sísmicos para Classificação de Multifácies

10th International Congress of the Brazilian Geophysical Society & EXPOGEF 2007, Rio de Janeiro, Brazil, 19-23 November 2007, 2007

Reconstrução Topológica Tridimensional de Objetos Geológicos em Bacias Marítimas Usando Dados Sísmicos 2D ou 3D: uma Ferramenta Exploratória e Explotatória de Hidrocarbonetos

10th International Congress of the Brazilian Geophysical Society & EXPOGEF 2007, Rio de Janeiro, Brazil, 19-23 November 2007, 2007

Geometry super-resolution by example

Proceedings of SIBGRAPI 2009 - 22nd Brazilian Symposium on Computer Graphics and Image Processing, 2009

. Super-resolution of a scanned keyboard with a high-resolution scan of one of its keys: original... more

Download

Arch generated shear bands in granular systems

Physica A: Statistical Mechanics and its Applications, 2009

We propose an arch based model, on cubic and square lattices, to simulate the internal mobility o... more

Alex Bordignon

Uploads

Papers by Alex Bordignon

Log In