Results 1 - 10
of
33
Change Detection Accuracy and Image Properties: A Study Using Simulated Data"; Remote Sens
, 2010
"... Abstract: Simulated data were used to investigate the relationships between image properties and change detection accuracy in a systematic manner. The image properties examined were class separability, radiometric normalization and image spectral band-to-band correlation. The change detection method ..."
Abstract
-
Cited by 6 (0 self)
- Add to MetaCart
Abstract: Simulated data were used to investigate the relationships between image properties and change detection accuracy in a systematic manner. The image properties examined were class separability, radiometric normalization and image spectral band-to-band correlation. The change detection methods evaluated were post-classification comparison, direct classification of multidate imagery, image differencing, principal component analysis, and change vector analysis. The simulated data experiments showed that the relative accuracy of the change detection methods varied with changes in image properties, thus confirming the hypothesis that caution should be used in generalizing from studies that use only a single image pair. In most cases, direct classification and post-classification comparison were the least sensitive to changes in the image properties of class separability, radiometric normalization error and band correlation. Furthermore, these methods generally produced the highest accuracy, or were amongst those with a high accuracy. PCA accuracy was highly variable; the use of four principal components consistently resulted in substantial decreased classification accuracy relative to using six components, or classification using the original six bands. The accuracy of image
Article Remote Sensing Images to Detect Soy Plantations in the Amazon Biome—The Soy Moratorium Initiative
, 2012
"... www.mdpi.com/journal/sustainability ..."
(Show Context)
Exploring Patterns and Effects of Aerosol Quantity Flag Anomalies in MODIS Surface Reflectance Products in the Tropics
, 2013
"... supplying a continuous data stream since 2000, lending to detailed time series analysis of the global terrestrial environment. This paper explores a quality anomaly present in the tropics relating to the aerosol quantity flag in the daily MODIS surface reflectance products (MOD09 series) and the 16- ..."
Abstract
-
Cited by 2 (0 self)
- Add to MetaCart
(Show Context)
supplying a continuous data stream since 2000, lending to detailed time series analysis of the global terrestrial environment. This paper explores a quality anomaly present in the tropics relating to the aerosol quantity flag in the daily MODIS surface reflectance products (MOD09 series) and the 16-day Vegetation Index (VI) composite products (MOD13 series) derived from the daily observations. While the anomaly is to some extent a known issue reported by the MODIS Land Quality Assessment group, very little is known about the scale of the issue, the nature and patterns of its occurrence, and potential consequences for data analysis, which explains why it is not adequately recognized throughout the literature. Two tropical regions were used to explore the anomaly and demonstrate the effects it has on the quality of selected MODIS products—one in the South American Amazon, the other in mainland Southeast Asia. The origins of the anomaly are described qualitatively in detail, and quantitative estimates of affected evergreen forest area in the MOD13A1 time series are made using blue band thresholding. The anomaly originates in the 1 km State dataset, whereby, under certain conditions, high aerosol quantity pixels are given a low aerosol quantity label, resulting in poor quality pixels with
Detecting spatiotemporal changes of corn developmental stages in the US corn belt using MODIS WDRVI data
- IEEE Trans. Geosci. Remote Sens
"... Abstract—The dates of crop developmental stages are impor-tant variables for many applications including assessment of the impact of abnormal weather on crop yield. Time-series 250-m vegetation-index (VI) data acquired from the Moderate Resolution Imaging Spectroradiometer (MODIS) provide valuable i ..."
Abstract
-
Cited by 2 (0 self)
- Add to MetaCart
Abstract—The dates of crop developmental stages are impor-tant variables for many applications including assessment of the impact of abnormal weather on crop yield. Time-series 250-m vegetation-index (VI) data acquired from the Moderate Resolution Imaging Spectroradiometer (MODIS) provide valuable informa-tion for monitoring the spatiotemporal changes of corn growth across large geographic areas. The goal of this study is to evalu-ate the performance of a new crop phenology detection method, namely, two-step filtering (TSF), for revealing the spatiotemporal pattern of specific corn developmental stages (early vegetative:
Investigation on the patterns of global vegetation change using a satellite-sensed vegetation index. Remote Sens
"... Abstract: The pattern of vegetation change in response to global change still remains a controversial issue. A Normalized Difference Vegetation Index (NDVI) dataset compiled by the Global Inventory Modeling and Mapping Studies (GIMMS) was used for analysis. For the period 1982–2006, GIMMS-NDVI analy ..."
Abstract
-
Cited by 2 (1 self)
- Add to MetaCart
(Show Context)
Abstract: The pattern of vegetation change in response to global change still remains a controversial issue. A Normalized Difference Vegetation Index (NDVI) dataset compiled by the Global Inventory Modeling and Mapping Studies (GIMMS) was used for analysis. For the period 1982–2006, GIMMS-NDVI analysis indicated that monthly NDVI changes show homogenous trends in middle and high latitude areas in the northern hemisphere and within, or near, the Tropic of Cancer and Capricorn; with obvious spatio-temporal heterogeneity on a global scale over the past two decades. The former areas featured increasing vegetation activity during growth seasons, and the latter areas experienced an even greater amplitude in places where precipitation is adequate. The discussion suggests that one should be cautious of using the NDVI time-series to analyze local vegetation dynamics because of its coarse resolution and uncertainties.
The Amazon Frontier of Land-Use Change: Croplands and Consequences for Greenhouse Gas Emissions
, 2010
"... ABSTRACT: The Brazilian Amazon is one of the most rapidly developing ag-ricultural frontiers in the world. The authors assess changes in cropland area and the intensification of cropping in the Brazilian agricultural frontier state of Mato Grosso using remote sensing and develop a greenhouse gas emi ..."
Abstract
-
Cited by 2 (0 self)
- Add to MetaCart
ABSTRACT: The Brazilian Amazon is one of the most rapidly developing ag-ricultural frontiers in the world. The authors assess changes in cropland area and the intensification of cropping in the Brazilian agricultural frontier state of Mato Grosso using remote sensing and develop a greenhouse gas emissions budget. The most common type of intensification in this region is a shift from single- to double-cropping patterns and associated changes in management, including increased fer-tilization. Using the enhanced vegetation index (EVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor, the authors created a green-leaf phenology for 2001–06 that was temporally smoothed with a wavelet filter. The wavelet-smoothed green-leaf phenology was analyzed to detect cropland areas and their cropping patterns. The authors document cropland extensification and double-cropping intensification validated with field data with 85 % accuracy for detecting croplands and 64 % and 89 % accuracy for detecting single- and double-cropping patterns, respectively. The results show that croplands more than doubled from 2001 to 2006 to cover about 100 000 km2 and that new double-cropping intensification
Universidade Federal de Lavras
"... How to cite Complete issue More information about this article Journal's homepage in redalyc.org Scientific Information System ..."
Abstract
- Add to MetaCart
(Show Context)
How to cite Complete issue More information about this article Journal's homepage in redalyc.org Scientific Information System
unknown title
"... Abstract – The objective of this work was to evaluate a simple, semi-automated methodology for mapping cropland areas in the state of Mato Grosso, Brazil. A Fourier transform was applied over a time series of vegetation index products from the moderate resolution imaging spectroradiometer (Modis) se ..."
Abstract
- Add to MetaCart
Abstract – The objective of this work was to evaluate a simple, semi-automated methodology for mapping cropland areas in the state of Mato Grosso, Brazil. A Fourier transform was applied over a time series of vegetation index products from the moderate resolution imaging spectroradiometer (Modis) sensor. This procedure allows for the evaluation of the amplitude of the periodic changes in vegetation response through time and the identification of areas with strong seasonal variation related to crop production. Annual cropland masks from 2006 to 2009 were generated and municipal cropland areas were estimated through remote sensing. We observed good agreement with official statistics on planted area, especially for municipalities with more than 10 % of cropland cover (R2 = 0.89), but poor agreement in municipalities with less than 5 % crop cover (R2 = 0.41). The assessed methodology can be used for annual cropland mapping over large production areas in Brazil. Index terms: cropland masks, cultivated area, Fourier, vegetation index. Estimativa de área agrícola por meio de séries temporais Modis NDVI no Estado do Mato Grosso Resumo – O objetivo deste trabalho foi avaliar um método simples, semiautomatizado, para o mapeamento
Analysis of MODIS 250 m NDVI Using Different Time-Series Data for Crop Type Separability
"... ii ..."
(Show Context)
Mapping and spatial analysis of the soybean agricultural frontier in Mato Grosso, Brazil, using remote sensing data
"... Abstract The main pioneer frontier considered by geographers is the Amazonian pioneer frontier. The occupation of the Brazilian territory has been carried out through successive economic cycles. Currently, the expansion of soybean crops in Amazonia is considered as the last economic cycle involving ..."
Abstract
- Add to MetaCart
(Show Context)
Abstract The main pioneer frontier considered by geographers is the Amazonian pioneer frontier. The occupation of the Brazilian territory has been carried out through successive economic cycles. Currently, the expansion of soybean crops in Amazonia is considered as the last economic cycle involving new migrations to still unexplored areas. Mapping this frontier is necessary in order to better understand its drivers and think about efficient land use policies to struggle its progress. In this paper, we propose an innovative methodology for mapping the agricultural frontier in the Amazonian state of Mato Grosso (Brazil) using satellite data acquired during the 2000–2006 period. We assume that the frontier evolves through successive land-use stages such as
