Los Sistemas de Información Geográfica en salud ambiental

This paper gives a brief introduction to the Geographic Information Systems (GIS) and its applications to the field of Environmental Health (EH). It starts with a conceptual exposition in order to show the potential of GIS’s as an space temporal analysers, and as an aids to take decisions. Some specific cases are analysed, these cases represent success applications of new technology to EH. A brief survey of the more popular software for GIS, free and commercial, is presented. It is also shown the connexion of this software with statistical software and other kind of specialize software in order to build computer tools for working in EH. Finally, some strategies are given for a deepen involvement of GIS in EH.En esta ponencia se presenta una breve introducción a los Sistemas de Información Geográfica (GIS, Geographic Information System) y sus aplicaciones en el área de Salud Ambiental (SA). Se inicia con una exposición conceptual para mostrar el potencial de los GIS como analizadores espacio-temporales, y como ayudas a la toma de decisiones. Se analizan algunos casos concretos, que han resultado un éxito, en la aplicación de las nuevas tecnologías en SA. También se hace una breve revisión del software más popular para un GIS, comercial y libre, y su conexión con otro software estadístico y especializado para construir herramientas informáticas apropiadas con las que trabajar en SA. Finalmente, se ofrecen algunas estrategias para logra una mayor utilización de los GIS en SA

A spatial contextual postclassification method for preserving linear objects in multispectral imagery

Classification of remote sensing multispectral data is important for segmenting images and thematic mapping and is generally the first step in feature extraction. Per-pixel classification, based on spectral information alone, generally produces noisy classification results. The introduction of spatial information has been shown to be beneficial in removing most of this noise. Probabilistic label relaxation (PLR) has proved to be advantageous using second-order statistics; here, we present a modified contextual probabilistic relaxation method based on imposing directional information in the joint probability with third-order statistics. The proposed method was tested in synthetic images and real images; the results are compared with a "Majority" algorithm and the classical PLR method. The proposed third-order method gives the best results, both visually and numerically

Change detection of buildings from satellite imagery and lidar data

Geospatial objects change over time and this necessitates periodic updating of the cartography that represents them. Currently, this updating is done manually, by interpreting aerial photographs, but this is an expensive and time-consuming process. While several kinds of geospatial objects are recognized, this article focuses on buildings. Specifically, we propose a novel automatic approach for detecting buildings that uses satellite imagery and laser scanner data as a tool for updating buildings for a vector geospatial database. We apply the support vector machine (SVM) classification algorithm to a joint satellite and laser data set for the extraction of buildings. SVM training is automatically carried out from the vector geospatial database. For visualization purposes, the changes are presented using a variation of the traffic-light map. The different colours assist human operators in performing the final cartographic updating. Most of the important changes were detected by the proposed method. The method not only detects changes, but also identifies inaccuracies in the cartography of the vector database. Small houses and low buildings surrounded by high trees present significant problems with regard to automatic detection compared to large houses and taller buildings. In addition to visual evaluation, this study was checked for completeness and correctness using numerical evaluation and receiver operating characteristic curves. The high values obtained for these parameters confirmed the efficacy of the method

Study of map projections with the second order theory

SEVILLA, M.J. "Estudio de las proyecciones cartográficas con la teoría de segundo orden". En: 5ª Asamblea Hispano Portuguesa de Geodesia y Geofísica, (Sevilla, 30 de enero - 3 de febrero de 2006)It is considered the isoparametric representation in the sense of O 'keefe for the local transformation of one surface in another. Then one of the surfaces is consider being aplane, therefore only one metric tensor is necessary to represent the properties of the transformation 01' final projection of the surface into the plane. Using Chovitz development to the second order for the metric tensor a matrix is proposed summing up the more important properties of the cartographic projection. Then it is easy 10 generate a infinite number of cartographic projections pro vides a method for the synthesis and unification of the different projections.Peer reviewe

The Goegraphic Information Systems in environmental health

En esta ponencia se presenta una breve introducción a los Sistemas de Información Geográfica (GIS, Geographic Information System) y sus aplicaciones en el área de Salud Ambiental (SA). Se inicia con una exposición conceptual para mostrar el potencial de los GIS como analizadores espacio-temporales, y como ayudas a la toma de decisiones. Se analizan algunos casos concretos, que han resultado un éxito, en la aplicación de las nuevas tecnologías en SA. También se hace una breve revisión del software más popular para un GIS, comercial y libre, y su conexión con otro software estadístico y especializado para construir herramientas informáticas apropiadas con las que trabajar en SA. Finalmente, se ofrecen algunas estrategias para logra una mayor utilización de los GIS en SA.This paper gives a brief introduction to the Geographic Information Systems (GIS) and its applications to the field of Environmental Health (EH). It starts with a conceptual exposition in order to show the potential of GIS’s as an space temporal analysers, and as an aids to take decisions. Some specific cases are analysed, these cases represent success applications of new technology to EH. A brief survey of the more popular software for GIS, free and commercial, is presented. It is also shown the connexion of this software with statistical software and other kind of specialize software in order to build computer tools for working in EH. Finally, some strategies are given for a deepen involvement of GIS in EH

Detection of vegetation changes in high resolution satellite imageries with Support Vector Machines and Mahalanobis distance algorithms

Abstract. Our objective is to compare the effectiveness of two algorithms, the Support Vector Machine (SVM) and the Mahalanobis distance, for the detection of vegetation changes in multispectral satellite images taken on two different dates. Classification methods are applied to each image to obtain a layer of probability of the vegetation, and later to detect possible changes. For this study two high-resolution satellite images taken in the 2005 and 2006 summers were used. Training the classification with very few pixels, Mahalanobis and SVM proved to be almost similar, however the latter algorithm shows a slight advantage in the visualization of changes

Un procedimiento para la elaboración de mapas de riesgos naturales aplicados a Honduras

Se plantea un método, basado en la Teoría de la Evidencia de Dempster-Shafer, para construir mapas de riesgos. Se explican procedimientos para la creación de mapas de exposición a inundaciones y para medir la vulnerabilidad del territorio. Para llevar a cabo los análisis se emplea el programa SIG IDRISI. El área analizada es Honduras