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After the students have browsed through the images, they are given specific directions on how to decide what features of the radar image indicate such structures as upland forest, clearcut areas, and roads.
Module 4 - Looking at Radar Images
Activities
A) Belize, Central America
1) Look in the directory
/Data/Mods1to5/Module04/Images/Belize.
You should find the
following files in there:
3) Locate Belize on a map of the world. What language(s) do you
think people
speak there?
4) The Mayan civilization flowered in the region of Belize over a thousand
years ago. What evidence do you think you might find of their existence
if you
visited there?
5) Look at the radar image of the northwest part of Belize
in 1978 in the file
SEASATim.gif (261K GIF).
Compare it with the radar image collected in 1990 in the
Mosaicim.gif (257K GIF).
What differences can you see? Why do you think the two
images look different?
6) Take a look at the radar image of the Gallon Jug ranch in the file
Lbandful.gif (1,260K GIF).
Compare it with the ground map shown in the
Belizkey.gif (8K GIF)
file. List the features shown in the ground map that are
visible in the radar image:
7) Compare the ground map in the file
Belizkey.gif (8K GIF)
with the vegetation map
generated from the radar data shown in the file
VegmpByt.gif (16K GIF).
A key to
the VegmpByt.gif file is displayed in the file
Vegmpkey.gif (2K GIF).
List the features shown in the ground map that
are also visible in the vegetation map:
8) Take a look at the photograph of a tropical rain forest in the file
GroundV1.gif (257K GIF)
and the sketch shown in the file
GroundV2.gif (11K GIF).
Draw a similar sketch of the trees and buildings
you would see if you walked a 30
meter line (100 yards) near where you live.
9) Display the file LBandRed.STK using the Sigma0 program
in the /Software/Sigma0 directory.
Select HV polarization for display. Use the mouse to point to the features
seen in the key below. Write down the backscatter values from the bottom
left-hand corner of the window in Sigma0.
10) How could you tell the difference between farmland and forest using radar backscatter?
11) Now draw a rectangle on the image within the upland forest by holding down
the mouse while dragging, then let go. Choose the Mean and Std Dev
option under the Statistics menu and a set of numbers will appear in
the Statistics window. Write down the numbers you see under the mean value
column. What type of scattering mechanism best matches the numbers you have
written down?
Module 4 - Looking at Radar Images
Activities
B) Death Valley, California
1) Look in the directory
/Data/Mods1to5/Module04/Images/DeathVal/PreSIRC.
You should find the
following files in there:
2) Display the images and the text contained in the /Data/Mods1to5/Module04/Images/DeathVal/PreSIRC directory. Take a look at the images and write down your impressions or thoughts about them.
3) Take a look at the Shuttle Hand-held photograph in file
Shuttlev.gif (337K GIF).
This is how the Mojave Desert looks to the crew of the
Space Shuttle as they fly over. Death Valley is outlined in yellow. What else
can you see in the image?
4) Now display the file
GroundV4.gif (106K GIF).
This shows the Hand-held photo
and four images taken from the ground at different spots. Why is there snow on
the ground in Picture A, yet people are seen wearing shorts in Picture C?
5) Display the topographic (height) map shown in file
Topomap1.gif (430K GIF).
Find the highest point and the lowest point in the image. Note down their
positions and their heights above or below sea level in meters.
6) Display the radar image in file
LBandFul.gif (1,370K GIF).
What do you think the very
bright areas seen in the image might be?
7) Display the file
VegmpByt.gif (41K GIF)
and the key in
vegmpkey.gif (2K GIF).
Circle the category which occurs most often in the Death Valley vegetation
map:
8) Which of these categories would appear most often in a similar map of where you live?
9) Display the file CBandRed.STK using the Sigma0 program.
Pick HH, HV or VV polarization for display. Point the mouse to any
point in the
image and look at the backscatter value in the bottom left-hand
corner of the
window. Is the backscatter (circle one):
10) Now draw a rectangle anywhere in the image by holding down the mouse while dragging, then let go. Choose the Mean and Std Dev option under the Statistics menu and a set of numbers will appear in the Statistics window. Write down the numbers you see under the mean value column. What type of scattering mechanism best matches the numbers you have written down?
Module 4 - Looking at Radar Images
Activities
C) Decade Volcanoes
* = SIR-C data from these volcanoes are included in this CD.
All of these volcanoes have been active within the last 20 years and some are currently active (in 1995). All are threats to the people that live on and around them.
1) Look in the directory called /Data/Mods1to5/Module04/Images/Volcano. The following files should be in the directory for this lesson:
2) Before you take a look at the images, map the locations of all the Decade Volcanoes on the map below.
Are most of these volcanoes located along the edges of continents or in the centers of the continents?
What are the volcanoes that are exceptions to this general statement?
3) Display the seven volcano images and the text contained in the
/Data/Mods1to5/Module04/Images/Volcano
directory. These volcanoes have been named the Decade Volcanoes
because they are particularly dangerous to the people that live on and around
them.
Use an atlas to determine the major
cities near each of these volcanoes and how close are they?
| Volcano | City | Distance from volcano to city |
|---|---|---|
| Colima | ||
| Galeras | ||
| Mauna Loa | ||
| Mount Rainier | ||
| Nyiragongo | ||
| Unzen | ||
| Taal |
4) The type of human activity on each volcano may be different. Look at the images for evidence of human activity such as cities and farm fields. What volcano appears to have the most human activity on it's flanks?
What are some of the reasons people live near such dangerous volcanoes?
5) The surface of a volcano changes over time due to the amount of volcanic
activity and the type of activity. The local climate can also affect how much
vegetation grows on a volcano and how quickly vegetation returns after an
eruption. Recently active volcanoes may produce lava flows
that resurface the
volcano giving it a fairly smooth look. Surfaces on less active
volcanoes may
be more deeply eroded. The appearance of the volcano surface is also
controlled by eruptive style. Some volcanoes produce fairly fluid lava that
spreads out over the surface. Other volcanoes produce thicker lava that tends
to plug up the volcano until it explodes.
Which images have evidence for lava flows?
Do lava flows always come from the same place? Why?
What evidence would you look for on each radar image that the lava flows are
all the same age or are different ages?
6) Go to the image titled
Rwanda.gif (408K GIF).
In addition to containing the
Nyiragongo Decade Volcano, this image contains the Virunga National Park, home
to the last surviving mountain gorillas. The park is the hook-shaped feature
at the center left of the image. The numerous mountain peaks are the Virunga
volcanoes within the park boundaries.
Why do you think the park boundaries show up so well on the radar image?
7) What are some of the advantages of using radar data to study volcanoes?
What are some things you can't learn about volcanoes from the radar
data?
Module 4 - Looking at Radar Images
Activities
D) Comparing Radar and Visible Light Images
1) Look in the directory called
/Data/Mods1to5/Module04/Images/ColorImg.
The following files should be in the directory for this lesson.
2) Display the images and the text contained in the /Data/Mods1to5/Module04/Images/ColorImg directory. There are some handheld photographs taken by the astronauts and some radar images of the same areas taken with the SIR-C radar.
3) Looking at the photographs
Locate these three sites on a world map. Based on their locations and the photographs taken by they astronauts, what do you think the climate of each site is? How does the amount and distribution of vegetation differ among the three images? Do you think people live in these areas?
Death Valley, California
Kliuchevskoi, Russia
Mt. Everest, Nepal
4) What kind of landforms, such as hills, mountains, rivers, streams can you
identify on each photograph? Do these landforms appear light or dark on each
photograph and why?
Here are some questions for each photograph to help you with your
investigation:
Death Valley, California
Are there any clouds in this photograph?
Do the clouds seem to cluster over certain types of landforms? What kinds?
How do you think the light areas differ from the darker areas in the
photograph?
Kliuchevskoi, Russia
What evidence of human activity do you see on the photograph?
What do you think is the source for the large dark cloud in the Kliuchevskoi
photograph?
Based on the shape of this dark cloud, is the prevailing wind direction?
Mt. Everest, Nepal
Does the pattern of snow cover give you any information about the topography of the area?
How do the glacier surfaces appear on the photograph?
Are there any clouds visible in the photographs?
5) Looking at the Radar Images
Now that you have characterized three areas based on the visible light photographs, take a look at the radar images of these same three sites. The radar image of Death Valley is a black and white image. The other two radar images, for Kliuchevskoi and Mt. Everest, have been colorized according to the following color scheme:
To make direct comparisons between two images, they should be collected at the same time under the same conditions. Otherwise some of the differences that you see between the two may be caused by other factors. In some areas the rate of change is slow enough that two datasets can be collected at about the same time and you can still make valid comparisons between the two.
The relative timing of the three pairs of hand-held photographs and radar images studied in this exercise is:
Identify the same landforms that you found in the visible light photographs. How do they look different in radar?
Do you see any additional evidence of human activity on the radar image
or does it give you the same type of information that the photograph does?
Does the volcanic ash cloud appear on the radar image? Why or why not?
Mt. Everest, Nepal
Why do you think the glaciers appear bright on the radar image?
Does there seem to be any correlation between where the snow occurs on the
photograph and a snow "SIGNATURE" on the radar image? Why or why not?
| Guided Tour | Lesson Table of Contents |
Converted to the IBM-PC by Al Wong, sirced03@southport.jpl.nasa.gov
Jet Propulsion Laboratory
4800 Oak Grove Drive
Pasadena, CA 91109
