RGISTools-package: 'RGISTools': Handling Multiplatform Satellite Images

Description Details I. Landsat functions II. MODIS functions III. Sentinel functions IV. Important general functions V. Remote sensing variables

Description

This package enables you downloading, customizing, and processing time series of satellite images from Landsat, MODIS and Sentinel in a standardized way. Some functions download and convert automatically the platform-specific file formats into GTiff, so they can be loaded in ‘R’. The customization functions support tile mosaicking, cropping, and deriving new variables of interest, such as the normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), etc. Tile mosaicking is required when the region of interest extends over several tiles, so they can be combined into a single image. Cropping involves removing the pixels outside the region of interest, making any analysis more computationally and memory efficient. Processing involves cloud mosaicking, compositing and filling/smoothing satellite data. Cloud masking eliminates the pixel values corresponding to clouds. Cloud removal and (measurement or processing) errors trigger data gaps and outliers, decreasing the quality and quantity of measurements. Hence, the package includes a set of functions for filling and smoothing the satellite imagery. The combination of functions in ‘RGISTools’ results in a stack of satellite images ready-to-use. Due to the wide variety of procedures and sources of information being handled in ‘RGISTools’, the functions are divided into 7 categories, which are identified by the first 3 characters of the function names;

  1. mod identifies MODIS Terra and Aqua satellite functions.

  2. sen identifies Sentinel functions.

  3. ls7 identifies Landsat-7 functions.

  4. ls8 identifies Landsat-8 functions.

  5. ls identifies both Landsat-7 and Landsat-8 functions.

  6. gen identifies function for being used in any of the three platforms.

  7. var identifies function for deriving variables in any of the three platforms.

Details

Below, there is a list of the most important functions grouped by satellite programs, and listed in operational order. These functions include searching, previewing, downloading, mosaicking, deriving new variables, compositing, cloud masking and filling/smoothing satellite imagery.

I. Landsat functions

The Landsat program is currently releasing imagery captured by two satellites; the Landsat-7 and Lansat-8. The functions for both satellites are separate due to discrepancies in their spectral coverage and data formats. To download Landsat imagery with the following functions, a USGS's ‘EarthExplorer’ account is required. Please, register here.

Landsat-7

ls7LoadMetadata Loads the Landsat-7 metadata file
ls7Search Searches a time series of Landsat-7 images
lsPreview Previews Landsat satellite images
lsDownload Downloads a time series of Landsat images
lsCloudMask Creates clouds masks for Landsat images
lsMosaic Mosaics Landsat images
ls7FolderToVar Computes new variables from Landsat-7 multispectral images
genSaveTSRData Saves a time series of images
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Landsat-8

ls8LoadMetadata Loads the Landsat-8 metadata file
ls8Search Searches a time series of Landsat-8 images
lsPreview Previews Landsat satellite images
lsDownload Downloads a time series of Landsat images
lsCloudMask Creates cloud masks for Landsat images
lsMosaic Mosaics Landsat images
ls8FolderToVar Computes new variables from Landsat-8 multispectral images
genSaveTSRData Saves a time series of images
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II. MODIS functions

Functions in ‘RGISTools’ download all land products from Terra and Aqua satellites. However, the processing focuses on the multispectral images. Be aware that an ‘EarthData’ account is required to use NASA's web service so, please, register here.

modSearch Searches a time series of MODIS images
modPreview Previews MODIS satellite images
modDownload Downloads a time series of MODIS images
modMosaic Mosaics MODIS images from the land products
modFolderToVar Computes new variables from MODIS multispectral images
modCloudMask Creates cloud masks for MODIS images
genSaveTSRData Saves a time series of images
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III. Sentinel functions

Sentinel archives provide a wide variety of products based on a 5-satellite constellation. The functions to download Sentinel images can cope with any product provided by ESA's ‘SciHub’ web service. However, image processing is focused on Sentinel-2 multispectal images. ‘SciHub’ credentials are required to download Sentinel imagery and can be obtained here.

senSearch Searches a time series of Sentinel images
senPreview Previews Sentinel images
senDownload Downloads a time series of Sentinel images
senMosaic Mosaics Sentinel-2 images
senCloudMask Creates cloud masks for Sentinel-2 images
senFolderToVar Computes new variables from Sentinel-2 multispectral images
genSaveTSRData Saves a time series of images
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IV. Important general functions

In addition to functions above, the package provides some general functions for a better data handling and processing:

genCompositions Creates compositions of images from a time series of satellite images
genSmoothingIMA Fills the gaps and smooths outliers in a time series of satellite images
genSmoothingCovIMA Fills the gaps and smooths outliers in a time series of satellite images using covariates
genPlotGIS Plots satellite images with a proper GIS format
genGetDates Gets the capturing date of an image from the name of a RasterLayer
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V. Remote sensing variables

New variables can be derived from multispectral images. The most common variables in the scientific literature are pre-programmed in ‘RGISTools’. They can be identified by the prefix "var".

varEVI Calculates the enhanced vegetation index (EVI)
varMSAVI2 Calculates the modified soil-adjusted vegetation index (MSAVI2)
varNBR Calculates the normalized burn ratio (NBR)
varNBR2 Calculates the normalized burn ratio 2 (NBR2)
varNDMI Calculates the normalized difference moisture index (NDMI)
varNDVI Calculates the normalized difference vegetation index (NDVI)
varNDWI Calculates the normalized difference water index (NDWI)
varRGB Generates a Red-Green-Blue (RGB) image
varSAVI Calculates the soil-adjusted vegetation index (SAVI)
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RGISTools documentation built on July 2, 2020, 3:58 a.m.