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NAME - Download user-requested products through the USGS TNM API


import, raster, USGS, NED, NAIP, parallel

SYNOPSIS --help [-idk] product=string [output_name=name] [ned_dataset=string] [input_srs=string] [resolution=float] [title_filter=string] [resampling_method=string] [memory=integer] [nprocs=integer] cache_size_tolerance=integer [output_directory=name] [--overwrite] [--help] [--verbose] [--quiet] [--ui]


Return USGS data information without downloading files
Download files only
Keep imported tiles in the mapset after patch
Allow output files to overwrite existing files
Print usage summary
Verbose module output
Quiet module output
Force launching GUI dialog


product=string [required]
USGS data product
Available USGS data products to query
Options: ned, naip, lidar
Name for output raster map
NED dataset
Available NED datasets to query
Options: ned1sec, ned13sec, ned19sec
Default: ned1sec
ned1sec: NED 1 arc-second
ned13sec: NED 1/3 arc-second
ned19sec: NED 1/9 arc-second
Input lidar dataset projection (WKT or EPSG, e.g. EPSG:4326)
Override input lidar dataset coordinate system using EPSG code or WKT definition
Resolution of lidar-based DSM
Filter available lidar tiles by their title (e.g. use "Phase4")
To avoid combining lidar from multiple years, use first -i flag and filter by tile title.
Resampling method to use
Options: default, nearest, bilinear, bicubic, lanczos, bilinear_f, bicubic_f, lanczos_f
Default: default
default: default method based on product
nearest: nearest neighbor
bilinear: bilinear interpolation
bicubic: bicubic interpolation
lanczos: lanczos filter
bilinear_f: bilinear interpolation with fallback
bicubic_f: bicubic interpolation with fallback
lanczos_f: lanczos filter with fallback
Maximum memory to be used (in MB)
Cache size for raster rows during import and reprojection
Default: 300
Number of processes which will be used for parallel import and reprojection
Default: 1
cache_size_tolerance=integer [required]
Tolerance for file size difference between cached file and stated download size
The size difference is used to recognize failed downloads and corrupted files, but some difference occurs naturally
Default: 20
Cache directory for download and processing
Defaults to system user cache directory (e.g., .cache)

Table of contents

DESCRIPTION downloads and patches selected USGS datasets (NED, NAIP, lidar) to the current GRASS computational region and coordinate reference system. Associated parameters are automatically passed to The National Map Access API, downloaded to a local cache directory, then imported, and patched together. supports the following datasets: National Land Cover Dataset (NLCD) is no longer available through the API.


NED data are available at resolutions of 1 arc-second (about 30 meters), 1/3 arc-second (about 10 meters), and in limited areas at 1/9 arc-second (about 3 meters).

NAIP is available at 1 m resolution.

Lidar data is available only for part of the US but there can be multiple spatially overlapping datasets from different years. All point clouds will be imported as points using and then patched and interpolated with In some cases, lidar point clouds do not have SRS information, use input_srs to specify it (e.g. "EPSG:2264"). If multiple tiles from different years are available, use title_filter to filter by their titles (e.g. "Phase1"). Use i flag to list the tiles first.

If the i flag is set, only information about data meeting the input parameters is displayed without downloading the data. If the d flag is set, data is downloaded but not imported and processed.

By default, downloaded files are kept in a user cache directory according to the operating system standards. These files can be reused in case a different, but overlapping, computational region is required. However, unzipped files and imported rasters before patching are removed. If the k flag is set, extracted files from compressed archives are also kept within the cache directory after the import. The location of the cache directory depends on the operating system. You can clear the cache by deleting the directory. Where this directory is depends on operating system, for example on Linux, it is under ~/.cache, on macOS under ~/Library/Caches, and on Microsoft Windows under the Application Data directory. If you have limited space or other special needs, you can set output_directory to a custom directory, e.g., /tmp on Linux. The custom directory needs to exist before calling this module.

By default, resampling method is chosen based on the nature of the dataset, bilinear for NED and nearest for NAIP. This can be changed with option resampling_method.


We will download NED 1/9 arc-second digital elevation model in the extent of raster 'elevation'. First, we just list the files to be downloaded:
g.region raster=elevation product=ned ned_dataset=ned19sec output_name=ned -i
USGS file(s) to download:
Total download size:	826.95 MB
Tile count:	4
USGS SRS:	wgs84
USGS tile titles:
USGS NED ned19_n35x75_w078x75_nc_statewide_2003 1/9 arc-second 2012 15 x 15 minute IMG
USGS NED ned19_n36x00_w078x75_nc_statewide_2003 1/9 arc-second 2012 15 x 15 minute IMG
USGS NED ned19_n35x75_w079x00_nc_statewide_2003 1/9 arc-second 2012 15 x 15 minute IMG
USGS NED ned19_n36x00_w079x00_nc_statewide_2003 1/9 arc-second 2012 15 x 15 minute IMG
To download USGS data, remove i flag, and rerun
We proceed with the download: product=ned ned_dataset=ned19sec output_name=ned
r.colors map=ned_small color=grey
We change the computational region to a smaller extent and create a new DEM, downloaded files will be used.
g.region n=224649 s=222000 w=633000 e=636000 product=ned ned_dataset=ned19sec output_name=ned_small
For a different extent we download NAIP imagery and we use a custom cache directory (replace /tmp by an existing path suitable for your operating system and needs):
g.region n=224649 s=222000 w=636000 e=639000 product=naip output_directory=/tmp output_name=ortho
NED and ortho
Figure: Downloaded NED (large and small extent), NAIP orthoimagery, and NLCD land cover (NLCD is not available since 2020 through the API)


TNM Access API Guide
National Elevation Dataset
National Land Cover Dataset


g.region, r.import, r.patch, r.colors,,


Zechariah Krautwurst, 2017 MGIST Candidate, North Carolina State University
(initial version, Google Summer of Code 2017, mentors: Anna Petrasova, Vaclav Petras)

Anna Petrasova, NCSU GeoForAll Lab
Vaclav Petras, NCSU GeoForAll Lab


Available at: source code (history)

Latest change: Tuesday Mar 21 14:44:24 2023 in commit: 565cf89b73f1fa17252a5c7a1ce1f035c65d6035

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