Landsat 7 World Mosaic, Acquired December 31, 2002

Justin McIntyre, Stephen Tressler, and Cynthia Brown

Presentation Overview

What is Remote Sensing?Landsat Data

From the Beginning…The Landsat ProjectA Closer Look at the Landsat 7 Project

MetadataWorld Reference SystemBrowse Images v. Actual Landsat DataCompleting Lab 4, Step by Step Instructions

Objective

At the conclusion of this presentation, you willunderstand Landsat 7 and the basic termsassociated with it. You will then use this

knowledge to obtain your own Landsat 7 ETM+browse image using Earth Explorer.

What is Remote Sensing?

Definition:The process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance from the targeted area.

Remote Sensing involves a different process than Orthoimagery…Orthoimagery combines the image characteristics of an aerial photograph with the geometric qualities of a map For Lab 3, we used Orthoimagery

Landsat 7 uses Remote Sensing…

LANDSAT: From the Beginning…

The Landsat Program was inspired by Apollo Moon-bound Missions1970: NASA began constructing the first Landsat Satellite 1972: Landsat 1 was launched

This began a new age of remote sensing of land from space

In 1975, the name of the project changed from Earth Resources and Technology Satellite to Landsat

LANDSAT: From the Beginning…

http://landsat.usgs.gov/project_facts/images/Timeline.jpg

LANDSAT: The Landsat Project

Uses a series of satellites to gather Earth Resource Data [ex- land mass, coastal boundaries, and coral reefs] Data acquired observes changes in the Earth’s land surface and the surrounding environmentsThe Landsat Project is supported by the USGS & NASA

NASA: develops and launches the spacecraftsUSGS: handles flight operations, maintenance, and manages ground data

LANDSAT: Landsat 5 & Landsat 7

Landsat 5 and Landsat 7 are both used todayLandsat 5 has no on-board recorders; it just downlinks acquired images to ground station antennasLandsat 7 has an on-board recorder and can easily collect data all over the worldThe repeat cycle for Landsat 5 and 7 is 16 daysLandsat 7 orbits 8 days behind Landsat 5

For this project, we will be using Landsat 7 ETM+ … lets take a closer look at it

LANDSAT: A Closer Look at the Landsat 7 Project

Launch InformationDate: April 15, 1999Vehicle: Delta II expendable launch vehicleLaunched by: NASALaunch Location: Western Test Range at Vandenberg AFB in California

Orbit InformationWRS- 2 path/row systemOrbits at an altitude of 705 km233 orbit cycle every 16 days, covering the entire globeCircles the earth every 98.9 minutes

Sensor Information:Enhanced Thematic Mapper Plus (more on this in the following slides)

LANDSAT: Landsat 7

Landsat is unmatched by other remote sensing systemsFine Resolution & Pin Point Accuracy

It is the most accurately calibrated Earth-Observing Satellite It provides continual coverage of land surfacesETM+, the Thematic Mapper onboard senses radiation in the visible, near-infrared, short-wave, and thermal infrared regions of the electromagnetic spectrumLandsat 7 was flawless until it lost its Scan Line Corrector

The Scan Line Corrector produced a rectilinear scan pattern, compensating and adjusting for the track motion of a spacecraft during a scanWithout SLC, the ETM+ line of sight traces a zig zag pattern across the satellite ground trackWithout SLC, the ETM+ still can acquire 75% of the data for any given scene

LANDSAT: Landsat 7 Uses

Studies land surfaces and coastal regions, showing how distinct environments are affected by global and regional climate changeMonitors important natural processes and human land use [ie, deforestation, coastal & river erosion, urbanization, and agriculture]Observes seasonal changes on continental and global scales

LANDSAT: A More In depth Look at ETM+

Landsat 5 uses a Thematic Mapper and a Multi-spectral Scanner Landsat 7 is equipped with an Enhanced Thematic Mapper (ETM+)ETM+ is more versatile and efficient for measuring global changesETM+ Features…

A panchromatic band with 15m spatial resolutionOn-board, full aperture absolute solar calibrator5% absolute radiometric calibration Thermal IR channel with 60m spatial resolutionOn-board data recorder

LANDSAT: Connections to the Text Module 5, Remotely Sensed Image Data

Landsat 5 uses TM, which features high spatial resolution and spectral sensitivityLandsat 7 was the first satellite launched with ETM+

Uses ETM+ to record electromagnetic energy (radiation) reflected and emitted by the Earth

Landsat 7 ETM+ has medium resolution with grid cells ranging from 15 to 80m

LANDSAT: How It Helps Our Society

Example: Collaboration for Cancer ResearchHuman Health Scientists have associated cancer and other neurological disorderswith exposure to agricultural chemicals Landsat satellite imagery is used to identify land cover features such as specific crop types, irrigation practices, and large animal feeding operations

Landsat shows cattle feedlots for Human Health Study

What does this mean? Landsat images help reconstruct historic land

cover information researchers integrate this information with other environmental data to

predict chemical exposure in human populations

Another Example…

These landsat 7 images show the damagethat New Orleans, Louisiana received

as a result of Hurricane Katrina.

New Orleans, April 24, 2005 New Orleans on the morning of August 30, 2005, just one day after Hurricane Katrina

made landfall

LANDSAT: Summing Up the Major Benefits of Landsat 7

Mission Continuity: Landsate 7 is the newest remote sensing satelliteGlobal Survey Mission: acquires data to build a global archive of sun-lit, almost cloud free images of Earth’s landmassesAffordable Data Products: available from the USGS at a lower price than commercial data sales; this also allows universities to use landsat data for scientific researchAbsolute Calibration: Uses ETM+ and is calibrated to better than 5%, serving as an on-orbit standard for cross-calibration of other Earth Remote Sensing MissionsResponsive Delivery: Products can be provided electronically within 48 hours of order

REVIEW: MetadataMetadata is the geographic data “in the can” (Lectures 8&9)Metadata helps us find the “missing information”

It tells us Who, What, When, Where, Why, and How It helps is decide if data is good or bad, and whether or not it its appropriate for our use.

For this Project, you will be obtaining the metadata file for the browse image you acquire on earth explorer

This will be essential for gathering the following information:The Scene Acquisition DateThe WRS Path and WRS RowThe Location and Extent of the Scene

(the coordinates of each corner, as well as the center)

WORLD REFERENCE SYSTEM: What is it?

The WRS is an indexing system for Landsat data 233 paths, 248 rows

The WRS Path represents the ground track of the satellite as it orbits the earthThe WRS Row refers to the latitudinal center line across a frame of imagery along a given path (ex- when a spacecraft moves along a path, the ETM+ scans the terrain below)The intersection of the paths and rows are used to identify landsat images

BROWSE IMAGES v. ACTUAL LANDSAT DATA

What’s the difference between Actual Landsat Data and a Browse Image?

The browse image is an online, digitally sub-sampled raster image of an individual sceneThe browse image is a visual overview, not a high quality digital representation like the actual landsat scene.

For this project, you will be using Earth Explorer to obtain a browse image

Completing Lab 4, Step by Step Instructions

Now that you have learned about Landsat 7 andthe basic terms associated with it, you will be able to use the knowledge obtained to acquire

your own Landsat 7 ETM+ browse image using Earth Explorer, then answer the

questions expected of you in Lab 4

For Step by Step Instructions…

Go to http://www.personal.psu.edu/cmb5010Under Project 4, click on “Completing Lab 4, Step by Step Instructions”

A word on obtaining your browse image

You will be using http://earthexplorer.usgs.govThe Step by Step instructions are very clearBut, Remember…

After you chose your town, you will need to select the type of data you want to acquire (LANDSAT 7 ETM+)When conducting your data search, it is important that you specify specific search criteria

Choose cloud coverage less than 10% Choose a normal data classification Choose day as your recording technique

A word on obtaining your Browse Image

While the program is searching for your specified criteria, the page will keep refreshing. The search is complete when the status box says complete. Once the search is complete, you can click on Landsat 7 ETM+ and choose an image from the Result Records with the least cloud coverage (“0” cloud coverage, if available) and the most recent acquisition date.

A word on obtaining your Browse Image

Also, remember that you must save the Browse Image as a .jpg in your www folder. You also need to save the Metadata file as a .html. Later, You will need to insert the browse image in your lab, and create a link to the metadata .html file.

Good Luck!

Sources for Future Reference…- Baxter, Ryan (2006). Geography 121 Lectures Lectures 8 & 9, Metadata.- Clemence, Lara (2006). Science Missions: Landsat 7. Retrieved October 31, 2006, from Earth Sciences Division,

NASA Web site: http://earthsciences.gsfc.nasa.gov/index.pl?iid=1928- DiBiase, David (2002). Understanding Geographic Data. Module 5: Remotely Sensed Data. Retrieved October 29,

2006 from ESRI Virtual Campus Website: http://campus.esri.com - Eurimage, (2006). Landsat. Retrieved November 1, 2006, from Eurimage Web site:

http://www.eurimage.com/products/landsat.html- Maxwell, Susan (2006, April 6). Collaboration for Cancer Research.

Retrieved October 31, 2006, from NASA Web site: http://landsat.gsfc.nasa.gov/news/news-archive/soc_0003.html

- NASA, (2005, 10 May). Chapter 1: Landsat 7 Program. Retrieved November 1, 2006, from NASA, Landsat 7 Science Data Users Handbook Web site: http://landsathandbook.gsfc.nasa.gov/handbook/handbook_htmls/chapter1/chapter1.html

- NASA, (2005, 10 May). Chapter 5: Orbit and Coverage. Retrieved November 1, 2006 from NASA, Landsat 7 Science Data Users Handbook Website: http://landsathandbook.gsfc.nasa.gov/handbook/handbook_htmls/chapter5/chapter5.html

- USGS, (2006, 5 September). Hurricane Katrina: Before and After in New Orleans. Retrieved November 1, 2006, from USGS Landsat Project Web site: http://landsat.usgs.gov/gallery/detail/412

- USGS, (2006, 9 August). Landsat 7 History. Retrieved November 1, 2006, from USGS Landsat Project Web site: http://landsat.usgs.gov/project_facts/history/landsat_7.php

- United States Geological Survey (2002) EarthExplorer. Retrieved November 1, 2006 from http://earthexplorer.usgs.gov

- Williams, Darrel (2006, 16 October). From the Beginning. Retrieved November 1, 2006, from NASA: The Landsat Program-History Web site: http://landsat.gsfc.nasa.gov/about/history.html

- Williams, Darrel (2006, 16 October). Landsat 7. Retrieved November 1, 2006, from NASA: The Landsat Program-History Web site: http://landsat.gsfc.nasa.gov/about/landsat7.html

If you have any problems…email us!

Cynthia cmb5010@psu.edu

Justin jgm5007@psu.edu

Stephen skt5012@psu.edu

To Sum Things Up…

Landsat 7 data is important for a wide and diverse remote sensing community!

It uses a series of satellites to gather important Earth

Resource Data