Downloading and Formatting Earth Images (Landsat satellite images) from NASA for GIS Use

Author:

Joseph J. Kerski, Ph.D.
Geographer:  Education/GIS
U.S. Geological Survey
Building 810 - Denver Federal Center - Entrance W-5 - Room 3000
Box 25046 - MS 507
Denver CO  80225-0046  USA
Tel: 303-202-4315
Fax:  303-202-4137
jjkerski@usgs.gov

Description:

This is a tutorial that will aid you in downloading Landsat satellite images into a GIS (such as ArcView or ArcGIS) from the NASA Zulu site.

First, access the following web site:

https://zulu.ssc.nasa.gov/mrsid

More recent Landsat images can be viewed and downloaded from http://landsat7.usgs.gov (although the resolution is 240 meters rather than 30 meters).

A good source of information about Landsat :  http://landsat.gsfc.nasa.gov/  

Another good source for free Landsat imagery is on the University of Maryland's Global Land Cover Facility:
http://glcf.umiacs.umd.edu/index.shtml

Landsat images are catalogued in parth and row.   A unique path and row combination exists for each satellite scene covering a specific chunk of the Earth's surface.   Let's say you want a specific area and you don't want to spend time browsing the maps on the above sites; rather, you want to use the above sites to go directly to the path and row that corresponds to the specific area on the Earth's surface you want to examine.  The following are some sites that provide the path and row.  You can use this information to then go to the above sites and download the image(s) you need.

1) There is a shapefile which can be used with various GIS apps at:

http://landsat7.usgs.gov/wrsprshape.php

Regarding the ARC shapefile... "A" refers to ascending node, meaning the scenes are acquired as the satellite is moving up behind the earth (dark side). These are basically night-time scenes, and are generally collected by the sensor only for calibration activities and/or thermal studies. Descending node ("D") would be the standard daytime scene reference, and these are what you probably want. The file is in geographic (lat-long) coordinates using the WGS-84 spheroid.

2) A printable map exists on:

http://ltpwww.gsfc.nasa.gov/IAS/handbook/handbook_htmls/chapter5/htmls/wrs_graphic.html

(3) Lat-long to path-row converter:

http://landsat7.usgs.gov/wrsconvert/index.html

the little graphic is off a bit from the actual path - row, but the lat - long is correct.

(4) When searching for the path/row of a particular location, the easiest way to do this would be via "GloVis" ( http://glovis.usgs.gov/ ), the
online search tool.

Once you enter the lat-long from the home page (or click on the map), you will immediately see a mosaic of browse/preview images with the path and row displayed for the currently active scene (highlighted).  Map layers may also be activated, if you need additional geographic reference.  Latitude and longitude (decimal degrees) for any point on your screen will be displayed in the lower left browser bar.

The world image displayed (shown below) is overlaid with rectangles. These rectangles are referred to as “mosaics” or “tiles”. These are the downloadable images. Each tile image was captured around the year 1990 (+/- 3 years).

These satellite images enable observation of large natural features, such as volcanoes, rivers, and forests, and large man-made features.  Major highways, office buildings (such as the Pentagon or US Capitol building), city parks and agricultural fields, airports, major bridges and dams are apparent, but narrow streets, creeks and streams, individual houses, and automobiles cannot be discerned. Here is a list of applications that have utilized Landsat data images:

General Uses:

                        Agriculture, Forestry, and Range Resources:

Discrimination of vegetative types: Crop types, Timber types, Range vegetation.
Measurement of crop acreage by species (estimating crop yields)
Measurement of timber acreage and volume by species (monitoring forest harvest)
Determination of range readiness and biomass
Determination of vegetation vigor
Determination of vegetation stress
Determination of soil conditions
Determination of soil association
Assessment of grass and forest fire damage

Land Use and Mapping:

Classification of land uses
Cartographic mapping and map updating
Categorization of land capability
Separation of urban and rural categories (monitoring urban growth)
Regional planning
Mapping of transportation networks
Mapping of land-water boundaries
Mapping of fractures

Geology:

Recognition of rock types
Mapping of major geologic units
Revising geologic maps
Delineation of unconsolidated rock and soils
Mapping igneous intrusions
Mapping recent volcanic surface deposits
Mapping landforms
Search for surface guides to mineralization
Determination of regional structures
Mapping linear features

Water Resources:

Determination of water boundaries and surface water area and volume
Mapping of floods and flood plains
Determination of areal extent of snow and snow boundaries (estimating snow melt runoff)
Measurement of glacial features
Measurement of sediment and turbidity patterns
Determination of water depth
Determination of irrigated fields
Inventory of lakes

Oceanography and Marine Resources:

Detection of living marine organisms
Determination of turbidity patterns and circulation
Mapping shoreline changes (tracing beach erosion)
Mapping of shoals and shallow areas
Mapping of ice for shipping
Study of eddies and waves

Environment:

Monitoring surface mining and reclamation
Mapping and monitoring of water pollution (e.g., tracing oil spills and pollutants)
Detection of air pollution and its effects
Determination of effects of natural disasters
Monitoring environmental effects of man's activities (e.g., lake eutrophication, defoliation, etc.)

GIS Uses:   

Geographic Information System (GIS) Uses:  With a GIS, you can:

1)  Use these images as base maps behind your field-collected coordinates.  The images, as your field-collected coordinates using a GPS (Global Positioning System) receiver, are both in Earth-referenced coordinates.  Therefore, the points you collect using your GPS will plot onto these maps. 

2)   Time-based  analysis can be accomplished by  comparing images of the same area that were captured at different times.

3)  Analyze the different spectral bands in the Landsat image to detect crop health, geology, greenness, and other characteristics of the Earth. 

Landsat Data Details:

 ·        Coverage:  The  Landsat mosaics are delivered in a Universal Transverse Mercator (UTM) / World Geodetic System 1984 (WGS84) projection.  The mosaics generally extend north-south over 5 degrees of latitude, and span east-west for the full width of the UTM zone.  For mosaics between 60 degrees north and 60 degrees south latitude, the width of the mosaic is the standard UTM zone width of 6 degrees of longitude.  For mosaics above 60 degrees of latitude, the UTM zone is widened to 12 degrees, centered on the standard UTM meridian.  To insure overlap between adjacent UTM zones, each mosaic extends for at least 50 kilometers to the east and west, and 1 kilometer to the north and south.

·        Pixel size: 28.5 meters,

·     Spectral Bands:   3 - Landsat Thematic Mapper bands

·        Band 7 (mid-infrared light) is displayed as red

·        Band 4 (near-infrared light) is displayed as green

·        Band 2 (visible green light) is displayed as blue

  ·  File Naming Convention:  Within each UTM zone the “partitions” extend from the equator to the north and south (in the northern and southern hemisphere respectively) in 5 degree increments.  The naming convention for the mosaics is three components, separated by hyphens; the first element is the hemisphere (either N or S), the second is the UTM zone number (1-60_, the last element is the latitude of the southern edge of the mosaic in the northern hemisphere and the northern edge of the mosaic in the southern hemisphere (there are some exceptions).  For example:

·        N-13-25_loc:  names a mosaic partition in the northern hemisphere, in UTM zone 13, extending between 25 and 30 degrees north latitude.

·        S-21-10_loc names a mosaic partition in the southern hemisphere, in UTM zone 21, extending between 10 and 15 degrees south latitude.

  The images have been orthorectified and  are delivered as 24-bit color uncompressed GeoTIFF files and  as 24-bit color MrSID compressed files.  The MrSID compressed file format is rapidly becoming accepted as the compression format of choice within a geodetic environment.  More information on the compression format and viewing software can be found at http://www.lizardtech.com.

Procedures for Downloading Landsat Images into ArcGIS (or ArcView):

1)      Go to https://zulu.ssc.nasa.gov/mrsid

2)      Click on “select image” at the bottom. Then click on the rectangle that you wish to download. A window will popup to allow you to specify where the downloaded file is to be sent

3)      The downloaded files are as follows:

These files are included in the downloaded file with a name like N-15-35.tar. This will download at a size of 26.2 MB.

                .met - EarthSat provided metadata.

                .sdw - MrSID World File, standard TFW style format.

                .sid - MrSID compressed mosaic of GeoTIFF file.

                .jpg - Browse image of MrSID compressed mosaic

The .met and the .sdw can be read as text files.

Below is a sample .sdw file:

28.500000000000000

0.000000000000000

0.000000000000000

-28.500000000000000

176215.499999999767169

4433061.000000005587935

The .jpg file can be opened  with any photo editor.

The .sid (MrSid file) will have to be uncompressed in order to use in ArcGIS.  Use a Unzip program (like WinZip) to do this.  Then, the file will be ready to be brought into ArcGIS.  If using ArcView, you first must turn on the extension for MrSid support using File --> Extensions. 

Below is a example of adding the MrSid file as a GIS layer in ESRI GIS software.

It is possible to locate a specific geographic location on the image in ArcGIS. The instructions to do this can be found on the bottom of the NASA web site. Click on “Where is it?” at the bottom of the screen.