R package - retrieving & using MODIS data from NASA LPDAAC archive
MODISTools is an R package for retrieving and using MODIS data subsets using ORNL DAAC web service (SOAP) for subsetting from Oak Ridge National Laboratory (ORNL). It provides a batch method for retrieving subsets of MODIS http://modis.gsfc.nasa.gov/ remotely sensed data and processing them to a format ready for user-friendly application in R, such as statistical modelling.
The most important function is
MODISSubsets, for requesting subsets from a given MODIS product for multiple time-series. Each time-series is defined by a coordinate location (WGS-1984), a surrounding area of interest, and a start and end date. Automating this as a batch process reduces time, effort, and human error. Alternatively,
MODISTransects expands upon
MODISSubsets by extracting MODIS data along a transect, and its surrounding neighbourhood. Downloaded subsets are saved in ASCII files, but can be converted to ASCII grid files for use in a GIS environment.
MODISSummaries computes summary statistics of downloaded subsets and organises summarised data back with the original input dataset, creating a csv file that can be easily used for modelling; this provides efficient storage of data and a transparent process from data collection, to processing, to a form that is ready for final use.
The functions were originally used for downloading vegetation indices data, but have been generalised to provide a package that performs the same functionality for any MODIS data that available through the web service. Other minor functions -- including a lat-long coordinate conversion tool -- are included to aid this process.
MODISTools was written by Sean Tuck and Helen Phillips. This package can be used under the terms of the GNU GPLv3 license; feel free to use and modify as you wish, but please cite our work where appropriate. To cite MODISTools in publications, please use:
Tuck, S.L., Phillips, H.R.P., Hintzen, R.E., Scharlemann, J.P.W., Purvis, A. and Hudson, L.N. (2014) MODISTools -- downloading and processing MODIS remotely sensed data in R. Ecology and Evolution, 4 (24), 4658--4668. DOI: 10.1002/ece3.1273.
Some of the changes in recent updates:
- New function,
MODISGrid, that takes downloaded ASCII files and converts them into ASCII grid files, which can be used in a GIS environment.
- Optional time-series plots for diagnostics as output from
MODISGridnow writes MODIS projection (PRJ) files for all ASCII raster grids, so their correct projection is defined. These files can now be loaded directly into a GIS environment.
MODISGridnow more flexibly deals with data files that contain multiple products.
- Citation for publication in Ecology and Evolution added.
- Documentation and 'Using MODISTools' vignette updated.
The package is being maintained, but not actively developed. Due to time constraints, I will no longer be able to add new features.
Frequently asked questions
Available MODIS products and versions
Not all MODIS products are available using
MODISTools (and the web service it uses). The list of products available using
MODISTools can be found by running
GetProducts(). There is no option for selecting different versions of products.
Other tools for accessing MODIS data in R are available:
- The package laads is under development, to provide an interface to the NASA API of MODIS Level 1 and Atmosphere data products.
ORNL DAAC FAQ
The Oak Ridge National Laboratory Distributed Active Archive Center (ORNL DAAC) has an FAQ here.
The most recent stable release can be installed from the CRAN repository, by running:
This is the recommended way to download.
Alternatively, the most up-to-date in-development version of
MODISTools can be installed from this github repository. To do this, install the package
devtools if you haven't already done so.
install_github, with this repository name, to install
MODISTools straight from github.
install_github("seantuck12/MODISTools", build_vignettes = TRUE)