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Student reflection activities:
- Prompt students to record what types of resolution
problems they would need to consider, if they were planning a remote
sensing mission.
- Spatial resolution: high resolution and low resolution.
- Temporal resolution: how many times will you fly
- Prompt students to make their own decisions for remote
sensing mission.
Assessment:
- Students define and develop an understanding of: swath,
spatial resolution, and temporal resolution.
- Students differentiate between temporal resolution and
spatial resolution.
- Students differentiate between high spatial resolution
and low spatial resolution.
Ideas for math lesson connections:
- The
students determine a sensor's maximum spatial resolution in terms of
the size of the area viewed by multiplying the instantaneous field of
view (IFOV) by the distance from the ground to the sensor. (See diagram
and explanation, 2.3 Spatial Resolution, Pixel Size, and Scale,
in the CCRS on-line remote
sensing tutorial
- Students practice skills using ratios and scale related
to resolution and using digital images, photographs, and maps.
Related National Education Math Standards:
Ideas for geography lesson connections:
- Students investigate the Hawaiian Islands. For example,
the students might create a report describing the location, climate,
history, culture, and geography of the island.
- Students learn how remote sensing images are produced
by engaging in the "How
does the spacecraft send us data?" activity.
Related National Education Geography Standards:
Ideas for technology lesson connections:
- Students
discuss the tradeoffs associated with high and low spatial resolution.
- Students
consider ethical issues associated with satellites and other remote
sensing platforms being used for nonscientific purposes.
Related National Education Science Technology Standards:
Activity sheet: Defining the
terms (PRSM-1) answer key
1. Swath - ANSWER:
the sensor "sees" a certain portion of the Earth's surface.
The area imaged on the surface, is referred to as the swath.
2. Spatial resolution - ANSWER:
describes how much detail in an image is visible to the human eye.
ANSWER:
- In low spatial resolution, we can see
large (gross characteristics) features in a larger ground area, but
we can't see the fine details of these features.
- In high spatial resolution, we can see
smaller details of the features. However, the higher the resolution,
the less total ground area can be seen.
3. Temporal resolution - ANSWER:
The frequency (number of repeat observations in a given length of time)
of observations of the same area of the Earth's surface during
a given period of time.
Activity sheet: Comparing ground truth images, airborne,
& satellite remote sensing images
(PRSM-2) answer key
- Where were these images taken?
The ground truth images were taken with an underwater camera by scuba divers
on the ocean floor in Kailua Bay, Oahu.
The airborne multi-spectral image was taken over a section
of Kailua Bay.
The airborne AVIRIS image was taken over Kaneohe Bay and Kailua
Bay. We then zoomed into our study area of Kailua Bay.
The Landsat satellite image was taken over the entire island of
Oahu. We then zoomed into our study area of Kailua Bay.
- What are the similarities?
They are all images that include Kailua Bay. The sensors that
record the images all measure reflected sunlight off the Earth’s surface
(and the ocean floor down to depths of about 30 meters).
- What are the differences?
They are different in terms of spatial resolution. We could see
much more detail in the ground truth images (underwater photographs)
compared to the airborne and satellite images. Ground truth images
have the highest spatial resolution. The multi-spectral airborne
images have the next highest spatial resolution (1 square meter per
pixel). The AVIRIS airborne image has a 20 meter spatial resolution
(400 square meters per pixel). The Landsat satellite image has 30
meter spatial resolution (900 square meters per pixel), the lowest
of the three types of images.
- What is the reason that these images are different?
The reason that these images are different is because the ground
truth images are collected in the water, the multi-spectral and
AVIRIS images are collected from airplanes, and the Landsat image
is collected from a satellite.
- What would you be able to describe using ground truth images?
In ground truth images, we could see details on specific locations
in Kailua Bay. We could see detail about the coral reef habitat such
as lush coral gardens, green algae fields, sand ripples on the ocean
floor, branching coral colonies, a coral “bomb” and even some fish.
We couldn’t see this sort of detail in the airborne or satellite image.
- What would you be able to describe using airborne and satellite images?
In the airborne muli-spectral image, we could see large-scale geological
features such as small islands (Flat Island) the meandering sand channel,
sand fields, islands in the Bay, shape of the coastline and Kailua town.
We could also see the overall texture of the reef.
In the airborne AVIRIS image, we could see both Kailua Bay, adjacent
Kaneohe Bay, and the surrounding towns. We could also see small islands
(Flat Island, the Mokolua Islands, and Coconut Island). There are lots
of clouds in the image which is one of the reasons why they are flying
another mission.
In the Landsat satellite image, we could see the whole landscape
of Oahu and how the area is laid out. We could see things such as cities,
mountain ranges, highways, agricultural fields, volcanic craters, white
caps on the North shore (big surf), the airport but couldn’t see the
detail images in specific location because the resolution of the Landsat
data is so coarse.
Why do you think ground truthing is necessary to plan the remote sensing
mission?
The ground truth images allows us to assist in the classification(i.e.
distinguishing sand from coral) of the airborne and satellite remote
sensing images (we will discuss the classification maps in more detail
in lesson 11). If we do not have any ground truth images (underwater
photographs), we would have a more difficult time distinguishing between
different features (i.e. high versus low percentage of coral cover)
within the airborne or satellite image. Ground truthing provides
a validation for the classification of airborne and satellite images.
Activity sheet: Planning a remote sensing mission
(PRSM-3) answer key
Mission statement
You are a member of an airborne mission scientist team. Your team's role
is to locate and evaluate the state of the reefs in Kailua Bay on Oahu.
Your team has access to AVIRIS as your remote sensing instrument
and NASA aircraft at Dryden Flight Research Center in California. Before
starting your mission, you need to present your remote sensing plan to
other scientists at NASA. So, what do you need to consider in your remote
sensing mission plan? Use what you know about remote sensing and the questions
below to create a mission plan.
1. The process
of remote sensing data collection:
What steps will you take to collect data for the remote sensing
mission?
Step 1: Confirm the use of AVIRIS as the
remote sensing instrument (example)
Step 2: Choose the appropriate NASA aircraft
for housing the AVIRIS
Step 3: Create a flight plan that provides
the data required to locate and evaluate the state of coral reefs are
in Kailua Bay including, altitude, flight path, time of flight, etc.
Step 4: Prepare aircraft, instruments, and
crew, Take off from NASA Dryden center
Step 5: Fly over Kailua Bay on Oahu.
Step 6: Collect the remote sensing images
and return to Dryden, make interim landings as required
2. The types of data
(remote sensing image):
1) What kinds of remote sensing
images will you collect and why will you collect those images?
ANSWER:
- Visible images: To see the features
of the coastal environment, including the coral reefs.
2) Which remotes sensing images will you collect
and why do you think those images are necessary?
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Remote sensing images
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Do I need these Images?
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Why do I need this image?
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Ground truth images
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Yes
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To have a record of what we have seen
on the ground. We can use the ground truth data in conjunction
with the airborne and satellite data to apply what we’ve seen in
a particular area to a larger spatial area.
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Airborne remote sensing images
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Yes
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To be able to discern larger scale geological
features.
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Satellite remote sensing images
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Yes
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To see how the location of Kailua Bay fits into the
larger context of Oahu.
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3. The method of data
collection:
Spatial resolution: What spatial resolution are you looking for in your
images (high or low) and why?
High resolution: ( Yes
No ) circle one (ANSWER: YES)
Why?:
ANSWER:
- I will collect high-resolution images since
I need detailed images of the coral reefs. The high- resolution images
provide detailed information about specific location of the coral reefs
given the features of the coastal environment.
Low resolution: (Yes
No) circle one (ANSWER: YES)
Why?:
ANSWER:
- I will collect low-resolution
images since I need an entire view of Oahu, especially on the east side
(Kailua Bay). The low-resolution images provide the information on the
location of Kailua Bay and puts the size of the bay in perspective with
the size of the island.
Temporal resolution and the swath: Are
you looking at changes in
the state of the reefs over time?
Changes over time: (Yes No) circle one (ANSWER: YES)
Why?:
ANSWER:
- The request for this mission was
to look at the state of the reefs in Kailua Bay. In order to assess
the state of the reefs, we must be able to compare the state of the
reefs in the past versus the present.
Why might you fly over Kailua Bay more than once for this mission?
ANSWER:
- Because the
swath of the instrument may not cover the entire area of Kailua Bay.
Use your responses to the questions on this worksheet to create
a plan for conducting a remote sensing mission over Kailua Bay. Be sure to state the mission
objective and a list the criteria for the mission including types
of images you will collect and the spatial and temporal resolution requirements.
You should be prepared to describe why each of the mission requirements
is necessary for addressing the mission objective.
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