Justin McIntyre, Stephen Tressler, and Cynthia Brown
Landsat 7 World Mosaic, Acquired December 31, 2002
Presentation Overview
What is Remote Sensing?
Landsat Data
From the Beginning…
The Landsat Project
A Closer Look at the Landsat 7 Project
Metadata
World Reference System
Browse Images v. Actual Landsat Data
Completing Lab 4, Step by Step Instructions
Objective
At the conclusion of this presentation, you will
understand Landsat 7 and the basic terms
associated 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 Missions
1970: 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 environments
The Landsat Project is supported by the USGS & NASA
NASA: develops and launches the spacecrafts
USGS: handles flight operations, maintenance, and
manages ground data
LANDSAT: Landsat 5 & Landsat 7
Landsat 5 and Landsat 7 are both used today
Landsat 5 has no on-board recorders; it just
downlinks acquired images to ground station
antennas
Landsat 7 has an on-board recorder and can
easily collect data all over the world
The repeat cycle for Landsat 5 and 7 is 16 days
Landsat 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 Information
Date: April 15, 1999
Vehicle: Delta II expendable launch vehicle
Launched by: NASA
Launch Location: Western Test Range at Vandenberg AFB in California
Orbit Information
WRS- 2 path/row system
Orbits at an altitude of 705 km
233 orbit cycle every 16 days, covering the entire globe
Circles 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 systems
Fine Resolution & Pin Point Accuracy
It is the most accurately calibrated Earth-Observing Satellite
It provides continual coverage of land surfaces
ETM+, the Thematic Mapper onboard senses radiation in the visible,
near-infrared, short-wave, and thermal infrared regions of the electromagnetic
spectrum
Landsat 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 scan
Without SLC, the ETM+ line of sight traces a zig zag pattern across the satellite
ground track
Without 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 change
Monitors 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 changes
ETM+ Features…
A panchromatic band with 15m spatial resolution
On-board, full aperture absolute solar calibrator
5% absolute radiometric calibration
Thermal IR channel with 60m spatial resolution
On-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 sensitivity
Landsat 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 Research
Human 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
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
Landsat shows cattle feedlots for Human Health Study
Another Example…
These landsat 7 images show the damage
that 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 satellite
Global Survey Mission: acquires data to build a global archive of sun-lit,
almost cloud free images of Earth’s landmasses
Affordable Data Products: available from the USGS at a lower price than
commercial data sales; this also allows universities to use landsat data for
scientific research
Absolute Calibration: Uses ETM+ and is calibrated to better than 5%,
serving as an on-orbit standard for cross-calibration of other Earth Remote
Sensing Missions
Responsive Delivery: Products can be provided electronically within 48
hours of order
REVIEW: Metadata
Metadata 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 Date
The WRS Path and WRS Row
The 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 earth
The 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
For this project, you will be using Earth Explorer to obtain a browse image
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 scene
The browse image is a visual overview, not a high
quality digital representation like the actual landsat
scene.
Completing Lab 4, Step by Step Instructions
Now that you have learned about Landsat 7 and
the 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/cmb5010
Under 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.gov
The Step by Step instructions are very clear
But, 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/newsarchive/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 ProgramHistory 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