1 / 18

GEOG 121 Project 4: Finding Landsat Data

GEOG 121 Project 4: Finding Landsat Data. Presented by: Dan LaSota Greg Stricker Weiqiang Lin. About Landsat: Purpose. The Landsat Program is established to acquire remote sensing imagery of the earth for monitoring and managing the Earth's resources.

elmer
Télécharger la présentation

GEOG 121 Project 4: Finding Landsat Data

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. GEOG 121 Project 4:Finding Landsat Data Presented by: Dan LaSota Greg Stricker Weiqiang Lin

  2. About Landsat: Purpose • The Landsat Program is established to acquire remote sensing imagery of the earth for monitoring and managing the Earth's resources. • Applications include: agriculture, geology, forestry, regional planning, education, national security and global climate change research. • Landsat 7 is the most recent NASA satellite among 6 others that have produced a continuous multispectral record of the Earth's land surface for 32 years now. • Special Emphasis on: Currency, accuracy, affordability and public accessibility of Landsat Data. • It is used across disciplines to achieve improved understanding of the Earth's land surfaces and the impact of humans on the environment.

  3. About Landsat: Brief History • NASA initiated an Earth Resources Survey (ERS) Program 1965 to develop methods for remote sensing of earth resources from space. • First Earth Resources Technology Satellite (Landsat 1) launched in 1972 with two Earth-viewing sensing systems • a return beam vidicon (RBV) – discontinued after Landsat 3 and • an 80 meter multispectral scanner (MSS). • Original MSS measures radiation within four narrow bands that span visible green wavelengths, visible red wavelengths, and slightly longer, near-IR wavelengths. • Landsat 4 launched in 1984 with the MSS and the Thematic Mapper (TM) featuring higher spatial resolution (30 meters) and improved spectral sensitivity (7 bands, including visible blue, two mid-infrared, & thermal infrared wavelengths). • The Landsat 7 Enhanced Thematic Mapper Plus (ETM+) Sensor was launched in Apr 1999, with improved resolution and precision, necessitated by the high costs of imaging, Land Remote Sensing Policy Act (1992) and the loss of Landsat 6. • Landsat is a tri-agency joint program of NASA, NOAA and the USGS.

  4. About Landsat: Satellite Characteristics Source: http://ltpwww.gsfc.nasa.gov/IAS/handbook/handbook_htmls/chapter1/chapter1.html#section1.1

  5. About Landsat: How it works? Space Segment • The ETM+ sensor onboard the spacecraft obtains data along the ground track at a fixed swath (185 km in width). • The orbit of Landsat 7 is repetitive, circular and near polar at a nominal altitude of 705 km (438 miles) at the Equator. • The spacecraft completes just over 14 orbits per day, covering the entire Earth between 81 degrees N & S latitude every 16 days. • A multispectral data set having high (30 meter) & medium to coarse (250 to 1000 meter) spatial resolution is acquired on a global basis repetitively. Source: http://ltpwww.gsfc.nasa.gov/IAS/handbook/handbook_htmls/chapter5/htmls/swath_pattern.html

  6. About Landsat: How it works? Ground Segment • Segment consists of both Landsat 7 unique components as well as institutional services. Some examples: • Landsat 7 Unique Components • Landsat Ground Station LGS, located at EDC, in Sioux Falls, SD is a receive site for the wideband X-Band downlinksof payload data from the space vehicle. • In addition to LGS, the Alaska Ground Station & the Svalbard Norway Ground Station receive payload data downlinks. • International Ground Stations are satellite data receiving stations located worldwide. They receive, process, & distribute services. • Institutional Services • Landsat Ground Networkprovides communication support. • Space Network – relay services • NASA Integrated Support Network – supports Institutional Services

  7. About Landsat: Products • Level 0R Product: an essentially raw data form that is marginally useful prior to radiometric and geometric correction. • Level 1R product is a radiometrically corrected 0R product. 1R product & 0R at input level have identical geometry. • The 1G product is available to users and is a radiometrically and systematically corrected 0R image. • Can be processed by LPGS or NLAPS • Geometrically rectified for sensor/satellite/terrestrial distortions • Scene rotated, aligned, & georeferenced to a user-defined map projection. • Earthexplorer always utilize the low gain LMAX value when scaling the radiance of a scene so that all pixels saturate at the same radiance. • Others: 1P (precision corrected), 1T (terrain corrected), SLC-off Products

  8. About Landsat: Distribution • Landsat 7 data distribution system will provide access to Landsat 7 Level 0R data products within 24 hours of collection, and • Level 1 processed products within 48 hours of request. • Media: • Exabyte tape • CD-ROM or • Electronic transfer via FTP • Imagery of foreign land masses will be recorded to EDC at Sioux Falls, yet the temporal depth will be a fraction of what's available at the international ground stations.

  9. What is SLC-off? • An instrument malfunction occurred onboard Landsat 7 on May 31, 2003. The problem was caused by failure of the Scan Line Corrector (SLC), which compensates for the forward motion of the satellite. • The center of a SLC-off data product is very similar in quality to previous Landsat 7 data. However, the scene's edges will contain alternating scan lines of missing data or duplicated data. • As of 5/10/2004, product is in 1G form and has the gap areas filled with Landsat 7 data acquired at a similar time of year prior to the failure. • EDC has reduced the price of Landsat 7 ETM+ SLC-off scenes from $600 to $250.

  10. What is SLC-off?

  11. What is SLC-off?

  12. Using Landsat Data… A Digression from SLC-off

  13. How to do Project 4 Generating Landsat Image To find coordinates: www.census.gov/cgi-bin/gazetteer To generate Landsat Image: http://earthexplorer.usgs.gov Click on “Enter as: Guest” Click on “Enter Coordinates” to do so in Decimals/DDMMSS Under Data Set Selection, check the box for “ETM+ SLC-off (Landsat 7, Jul 2003 – Present) Click “Continue”, then “Search” on the following page When the search is completed, click on the Data Set “ETM+ SLC-off (Landsat 7, July 2003 - present)”

  14. How to do Project 4 Creating the Report • Click on the “Show” button, under the column “Preview Image”, that corresponds to the smallest amount of cloud cover and the most recent image. • Right click to Save Picture As (e.g. jpg) for Project 4. • Click on the “Show” button under “Show All Fields” for your image to show metadata. • Hyperlink the metadata to Project 4 - OR • Click on File and choose “Properties” • Copy the URL for the metadata • Create new page for metadata using Microsoft Frontpage • Upload it to Pass Explorer • Provide a link in Project 4 to this Metadata Page.

  15. How to do Project 4 Answering the Questions • Note Scene Acquisition Date for the image you have selected. • The World Reference System (WRS) indexes orbits (paths) and scene centers (rows) into a global grid system, comprising 233 paths by 248 rows. • The standard WRS scene as defined for Landsats 4 and 5 was preserved as a product for Landsat 7. • A path distance of 90 kilometers before and after a WRS center point defines the standard scene length of 180 km (includes 20 scans of overlap) The standard WRS scene overlaps neighboring scenes along a path by 5% at the equator and has a width or cross track distance of 185 kilometers. • Definitions • The term row refers to the latitudinal center line across a frame of imagery along any given path. • The intersection of rows and paths produces the nominal scene center for that landsat image • The path/row numbers do not coincide with latitudes 90° north and south.

  16. How to do Project 4 Answering the Questions

  17. How to do Project 4 Answering the Questions • Location and Extent of the Scene • Coordinates of the NW, NE, SW and SE corners can be found in the metadata • Cost of actual Landsat scene that corresponds to the free browse image: • USGS Landsat ETM+ : $600.00 for first scene • USGS Landsat ETM+ SLC-Off : $250.00 for first scene • http://edcsns17.cr.usgs.gov/helpdocs/prices.html#LANDSAT_ETM+

  18. Sources • NASA Landsat Program (2004) http://geo.arc.nasa.gov/sge/landsat/landsat.html • Landsat 7 Science Data Users Handbook (2004) http://ltpwww.gsfc.nasa.gov/IAS/handbook/handbook_toc.html • U.S. Census Bureau (2000) www.census.gov/cgi-bin/gazetteer • USGS Earthexplorer (2004) http://earthexplorer.usgs.gov • USGS Landsat Project (2004) http://landsat.usgs.gov/programdesc.html • Esri Online Campus (2004) http://campus.esri.com

More Related