The use of remote sensing techniques by Modis (MCD45A1) images using to identify and evaluate burned areas in the metropolitan region of Belo Horizonte - MG, Brazil

The study of fire burned areas is very important, since they corroborate with control measures, prevention and monitoring of fires. Forest fires causes numerous impacts, among them, there is biodiversity lost and human health prejudice. So, it is a problem of environmental sphere as well as a social and political sphere. A way of monitoring this is using remote sensing techniques. So the propose of the present article is to use the Modis product (MCD45A1) to identify and evaluated the burned areas in metropolitan region of Belo Horizonte, among the years of 2012 to 2016, which is validated with Landsat-8/OLI sensor data. With the use of Landsat data it is possible to define the size of the burned area with greater precision, but requiring technical operational knowledge and specialized technical staff for both, on the other side, Modis is easier to operate, and have direct application and higher availability. It was observed that the study area has high burned area occurrences, mainly in spring and winter. The results found here could be used for future studies to decrease the forest fires incidence in the region and thus preserve the biodiversity of important biomes present in it.Estudos sobre a ocorrência de queimadas são muito importantes, visto que eles corroboram medidas de controle, prevenção e monitoramento destas. Incêndios florestais causam vários impactos, entre eles perda da biodiversidade e prejuízo à saúde humana, sendo um problema tanto na esfera ambiental quanto social e política. Uma forma de monitoramento desses incêndios é a utilização de técnicas de sensoriamento remoto. Assim, a proposta do presente trabalho foi a utilização de imagens Modis (MCD45A1) para identificação e avaliação de áreas queimadas na região metropolitana de Belo Horizonte, entre os anos de 2012 e 2016, validando-o com dados do sensor Landsat-8/OLI. Com o emprego dos dados Landsat, é possível delimitar com melhor precisão a dimensão da área queimada, mas exigindo-se conhecimento técnico operacional e corpo técnico especializado para tanto. Já o produto decorrente do Modis, é mais acessível e de fácil utilização, sendo de aplicação direta, pois já informa os focos de incêndio. Observou-se grande ocorrência de queimadas na região de estudo, principalmente na primavera e no inverno. Os resultados encontrados aqui poderão ser utilizados em estudos futuros para diminuir a incidência de queimadas na região e assim preservar a biodiversidade de biomas importantes nela presente

ALTIMETRY ASSESSMENT OF ASTER GDEM v2 AND SRTM v3 DIGITAL ELEVATION MODELS: A CASE STUDY IN URBAN AREA OF BELO HORIZONTE, MG, BRAZIL

This work is an altimetry evaluation study involving Digital Elevation Models ASTER GDEM version 2 and SRTM version 3. Both models are readily available free of charge, however as they are built from different remote sensing methods it is also expected that they present different data qualities. LIDAR data with 25 cm vertical accuracy were used as reference for assessment validation. The evaluation study, carried out in urbanized area, investigated the distribution of the residuals and the relationship between the observed errors with land slopeclasses. Remote sensing principles, quantitative statistical methods and the Cartographic Accuracy Standard of Digital Mapping Products (PEC-PCD) were considered. The results indicated strong positive linear correlation and the existence of a functional relationship between the evaluated models and the reference model. Residuals between -4.36 m and 3.11 m grouped 47.7% of samples corresponding to ASTER GDEM and 63.7% of samples corresponding to SRTM. In both evaluated models, Root Mean Square Error values increased with increasing of land slope. Considering 1: 50,000 mapping scale the PEC-PCD classification indicated class B standard for SRTM and class C for ASTER GDEM. In all analyzes, SRTM presented smaller altimetry errors compared to ASTER GDEM, except in areas with steep relief

Teaching Methodology for Topography: Didactic Proposal for the Free Station Survey Method

This article presents an innovative proposal for teaching Topography topics, as there are no qualified official publications on the subject of study referring to topographic positioning by the free station method, resulting in a shortage of didactic material on this topic in educational institutions in Brazil. Thus, the research work resulted from the didactics applied in the Topography discipline, of the UFPE's Cartographic Engineering degree program. It was proposed to the students to accomplish some practices of the free station method during the Topography discipline development. Thus, the students carried out a theoretical study on the topic. Subsequently, field work was developed with topographic equipment containing a program for surveying by free station method. Topographic vertices of the cadastral reference network of the “Joaquim Amazonas” campus of UFPE served as reference and adjustment points. A comparative analysis of the results calculated manually with the results obtained by the internal programs of the topographic equipment was carried out, using the official coordinates of the cadastral network as references. A program was developed in MATLAB for fixing the learning, whose results were also compared with the same official reference coordinates. This made it possible to generate a complete quantitative statistical analysis of the results

ALTIMETRY ASSESSMENT OF ASTER GDEM v2 AND SRTM v3 DIGITAL ELEVATION MODELS: A CASE STUDY IN URBAN AREA OF BELO HORIZONTE, MG, BRAZIL

Abstract: This work is an altimetry evaluation study involving Digital Elevation Models ASTER GDEM version 2 and SRTM version 3. Both models are readily available free of charge, however as they are built from different remote sensing methods it is also expected that they present different data qualities. LIDAR data with 25 cm vertical accuracy were used as reference for assessment validation. The evaluation study, carried out in urbanized area, investigated the distribution of the residuals and the relationship between the observed errors with land slope classes. Remote sensing principles, quantitative statistical methods and the Cartographic Accuracy Standard of Digital Mapping Products (PEC-PCD) were considered. The results indicated strong positive linear correlation and the existence of a functional relationship between the evaluated models and the reference model. Residuals between -4.36 m and 3.11 m grouped 47.7% of samples corresponding to ASTER GDEM and 63.7% of samples corresponding to SRTM. In both evaluated models, Root Mean Square Error values increased with increasing of land slope. Considering 1: 50,000 mapping scale the PEC-PCD classification indicated class B standard for SRTM and class C for ASTER GDEM. In all analyzes, SRTM presented smaller altimetry errors compared to ASTER GDEM, except in areas with steep relief