The purpose of the resource is to investigate changes in the major land cover types of Study Sites by examining Landsat satellite images acquired years apart. Educational levels: Middle school, High school

The GLOBE Program, University Corporation for Atmospheric Research (UCAR)

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Digital Library for Earth System Education

GLOBE® 2005 Change Detection Protocol - 1 Land Cover/Biology
Learning A
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ppendix
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Introduction
Protocols
Land Cover Change  
Detection Protocol
Purpose
Using Multispec software, evaluate and investigate 
changes that have occurred in the major land cover 
types of your GLOBE Study Site by examining the 
digital files of two Landsat satellite images that 
were acquired a few years apart.
Overview
Using MultiSpec software, students compare two 
registered images, acquired several years apart, 
of a GLOBE Study Site and identify changes in 
land cover. 
Student Outcomes
Science Concepts
Life Science
Organisms can change the environment in 
which they live.
Earth has many different environments 
that support different combinations of 
organisms.
All organisms must be able to obtain and 
use resources while living in a constantly 
changing environment.
All populations living together and the 
physical factors with which they interact 
constitute an ecosystem.
Humans can change ecosystem balance.
Geography
How to use maps (real and imaginary)
The physical characteristics of place
The characteristics and spatial distribution of 
ecosystems
How humans modify the environment
Scientific Inquiry Abilities
Use land cover data and appropriate tools and 
technology to interpret change.
Gathering spatial data and historical data to 
determine validity of change hypotheses.
Identify answerable questions.
Design and conduct scientific investigations.
Develop descriptions and predictions using 
evidence.
Recognize and analyze alternative 
explanations.
Communicate procedures, descriptions, and 
predictions.
Level
Middle and secondary
Time
Two or three class periods
Frequency
One time, but may be an iterative process as you 
progressively investigate more areas within your 
GLOBE Study Site
Materials and Tools
Computer
MultiSpec computer software (provided by 
GLOBE or downloaded from the Web)
2 - Landsat TM registered image datasets 
of the 15 km x 15 km GLOBE Study 
Site (disks provided by GLOBE), one 
recent, one a few years old, acquired at 
approximately the same time of year
Printed Landsat TM images of the  
15 km x 15 km GLOBE Study Site from 
the datasets
Student land cover type map(s) of the 
GLOBE Study Site
Topographic maps of your area (if available)
Aerial photos of your area (if available)
Introduction to the MultiSpec Program and 
Change Detection Tutorial
MUC data from previous land cover type 
map classifications 
Preparation
Install the MultiSpec software on the computers 
students will be using.
Install the images on the computers the students 
will be using. 
Familiarize yourself with MultiSpec and the 
Change Detection Tutorial.
Prerequisites
Review and practice the Introduction to the 
MultiSpec Program and the Change Detection 
Tutorial.
GLOBE® 2005 Change Detection Protocol - 2 Land Cover/Biology
Land Cover Change 
Detection Protocol – 
Introduction
Compare the two satellite images of your GLOBE 
Study Site. One was acquired before the other. 
However, the images have been registered. 
Registration is when the images are lined up so 
that every point on one image can be placed on 
top and matched with the same point on the other 
image. What has changed between the images? 
Can you see changes in your community’s size, 
shape or dominant land cover? Is your school still 
surrounded by the same land cover classes? Can 
you see more vegetated areas in an image? Has 
there been a big event, such as a flood, earthquake, 
drought, hurricane, tornado, etc., which has 
changed your landscape? Has the type or size of 
natural areas changed? Are there more houses on 
your way to school? Can you see evidence of these 
changes in your satellite images? 
Work on your own or with a partner. Make a list 
of questions about what you see in the images. Is 
there anything that you would like to know about 
these images regarding the change you may see? 
Some changes may not be easy to see but they 
are there. 
Narrow your list down to one question. Once you 
have a question, come up with a plan to answer 
your question. You will need to use the Field Guide 
for Land Cover Change Detection Protocol and/or 
some of the other Land Cover Field Guides. In the 
Land Cover Change Detection Protocol, you composite 
the two satellite images. Compositing is combining 
two registered images into one. After that, you use 
the MultiSpec software to look for change. 
Scientists use the same process to answer their 
questions about changes in satellite imagery. First 
they look at different images. Then they come up 
with questions they have about the images. Once 
they have decided on one question, they use 
scientific protocols or field techniques to answer 
it. Scientists may have to add new protocols or use 
ones that have already been used. You can do the 
same thing in GLOBE with the Land Cover/Biology 
Protocols. 
Land cover change maps are a major product 
created from remotely sensed data. Keeping track 
of change is important to our understanding of the 
earth as a system. Knowing about these changes 
is the first step towards understanding why and 
where they happen. Change data can be used to 
update maps. It can also be used to estimate the 
rates of change in certain areas. 
GLOBE® 2005 Change Detection Protocol - 3 Land Cover/Biology
Learning A
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Introduction
Protocols
Teacher Support
The Measurement
The Land Cover Change Detection Protocol is the 
culmination of the Land Cover/Biology Investigation. 
In order to get to this point, students will have 
had to use the Land Cover Sample Site and Biometry 
Protocols to collect MUC data, and then used these 
data to create maps from their satellite image. In 
terms of understanding land cover, your students 
should be sophisticated and ready to be motivated 
to learn about the changes in their GLOBE Study 
Site that have taken place over time. They should 
be interested in tracking how future changes 
might influence the landscape. This protocol is 
the application of the protocols that have come 
before it and a point where there is room to 
incorporate other Investigations, if you have not 
already done so. The land cover of your GLOBE 
Study Site can influence temperature and in some 
cases, precipitation in your area. The history of 
the land cover can also influence the soil and the 
water bodies that are close to it. For example, 
heavily farmed areas that are now forest may have 
soil properties that indicate this. Currently farmed 
areas with high nitrogen levels in the soil can 
influence nitrogen values in a water body close to 
the field. It goes without saying that temperature, 
precipitation, soil and hydrology can also influence 
the types of land cover in an area. For instance, a 
drought can cause a field of herbaceous vegetation 
to die off. Tundra is not found near the equator. 
There are other relationships that you and your 
students may want to explore. The Land Cover 
Change Detection Protocol can be the starting point 
for exploring questions about such relationships. 
The student introduction can hopefully start 
your students thinking along those lines but 
they may also bring their own questions, such 
as how a new residential development in their 
neighborhood may influence their water supply 
or a neighboring wetland. Although the protocol 
directions themselves are simple, the true meaning 
of the protocol is in using it to identify and explore 
your students’ questions about their changing 
landscape. 
Obtaining Landsat Data
Your school may have already received more than 
one Landsat image; however, this protocol requires 
that the two scenes being compared be registered 
to one another and acquired at the same time of 
year. You may request scene pairs from GLOBE 
by contacting your Country Coordinator, US 
Partner, or the GLOBE Help Desk. Before making 
this request, your school must complete the 
Computer-aided Land Cover Mapping Protocol and 
have reported measurements for at least 10 Land 
Cover Sample Sites to GLOBE.
Teacher Follow-Up: For each band combination 
that you use to investigate change, use the File 
menu to save the image onto a disk as a TIFF 
file. If you have a color printer, print copies for 
comparison to your student-produced land cover 
maps. Students should prepare a summary on the 
nature of the changes they have discovered. Send 
copies of your land cover maps, change images, 
and student summary to the GLOBE Student 
Data Archive by following the directions given in 
the How to Submit Photos and Maps section of the 
Implementation Guide.
Supporting Measurements
All the Land Cover/Biology Protocols
Student Preparation
Have an understanding of MUC
Implementation of the Land Cover Sample Site 
Protocol at least 10 times
Completion and understanding of the Computer-
aided Land Cover Mapping Protocol
Review and practice the Introduction to the MultiSpec 
Program and the Change Detection Tutorial
GLOBE® 2005 Change Detection Protocol - 4 Land Cover/Biology
Helpful Hints
• When your students look at the two 
images, they might not see any major areas 
of change between them. This does not 
mean that change has not occurred, only 
that the changes are relatively small.
• Comparing a single Landsat channel 
between two years is helpful for looking 
at changes for different land cover types. 
Each channel has specific applications 
based on the spectral signatures of the 
different land cover types.
• If a pixel in the newer image is brighter 
than in the older image, that pixel will 
show green. This means an increase in the 
property being measured. 
• If a pixel in the older image has a higher 
reflectance, the red and blue will produce 
magenta, indicating a decrease in the 
measured quantity in the newer image. 
• Since strong visible reflectance is often 
associated with exposed mineral materials 
(urban development, rocks, bare 
ground) we might infer that in a (1, 6, 1) 
combination, green areas have undergone 
an increase in urban development. Landsat 
channel 1 (blue) is useful for human-made 
features.
• It is important to consider the time of year 
each satellite image was acquired. Most 
of the time, your images will be at the 
same time of year but there may be a few 
crucial weeks of difference between them. 
For example, in one image, the leaf foliage 
may not be completely out or certain crops 
may not have been planted in agricultural 
fields. In a (4,9,4) combination, when 
green areas in two different images taken 
at different times of the year are evident, 
we are faced with the problem of deciding 
how much of the change is due to a real 
increase in vegetated area, and how much 
is due to seasonal variations. (See the 
example in the Durham, NH, images in the 
Change Detection Tutorial.)
• If we can find locations that appear to 
show an increase in vegetation in the 
newer image, we might infer more strongly 
that these represent areas of real vegetation 
increase. Conversely, areas of magenta 
in the newer image that appear green in 
the older image could represent areas of 
vegetative decrease. Landsat channel 4 
(near infrared) is useful for vegetated areas. 
• Have your students fill in the names of the 
files they will be using on their Field Guide. 
Questions for Further Investigation
• Which land cover type (MUC class) 
changed the most? What are some causes 
of this change?
• Generally, was there an increase or 
decrease in vegetation? 
• Look at other areas of change. Try to 
explain why these changes occurred. 
Are these changes because your satellite 
images are from different time periods 
(i.e. summer vs. winter, drought vs. rainy 
season), or was there human influence, 
or a major environmental event (i.e. fire, 
flood, etc.)? 
• How can you use this change information 
to help your community?
• How would your satellite image change 
if you compared different seasons? How 
would the composite image appear? 
• What is the effect of temperature and 
precipitation in the time immediately 
preceding the images? Students will have 
to research this question.
• If you live in a coastal region, what is 
the effect of the position of the tides? 
You will have to research the times of 
high and low tides on the dates of your 
images. Remember that Landsat images are 
acquired in the morning.
GLOBE® 2005 Change Detection Protocol - 5 Land Cover/Biology
Change Detection Protocol
Field Guide 
Task
Use MultiSpec to combine the digital data for two images of your GLOBE Study Site (acquired a few 
years apart) into one composite image and analyze the composite to learn about the land cover type 
changes that have occurred.
What You Need
❑  Introduction to the MultiSpec  
 Program and the Change Detection   
 Tutorial
❑  MultiSpec computer software
❑  MUC data from previous land  
 cover type map classifications
❑  2 - 512 x 512 pixel Landsat TM  
 registered image data of the 15 km  
 x 15 km GLOBE Study Site (disks  
 provided by GLOBE), one recent,  
 one a few years old
❑  Computer 
What To Do
1. Compare the hard copies of the Landsat TM images from the two different dates. What are the 
differences that you see between them? 
2. Start the MultiSpec program on the computer.
3. From the File menu, select Open Image. 
4. Select and open the older image of your GLOBE Study Site. It is labeled _________________. 
Follow the defaults in the Change Detection Tutorial.
5. Select and open the newer image of your GLOBE Study Site. It is labeled _________________. 
Check the Link to Active File box.
6. Reformat, name and save the new image (called _______________) using the directions in the 
Change Detection Tutorial. 
7. Open the new image and follow the directions in the Change Detection Tutorial for saving the 
statistics. 
8. Examine the image for change by following the defaults in the Change Detection Tutorial. 
9. Save the developed land cover image (1, 6, 1) and the vegetative image (4, 9, 4) used for 
comparison as TIFF files. See you teacher for further instructions on submitting them to 
GLOBE. 
GLOBE® 2005 Change Detection Protocol - 6 Land Cover/Biology
Looking at the Data
Are the data reasonable?
After you have completed the production of your 
Land Cover Change Image, you will have drawn 
some conclusions about which land cover types 
have shown increases or decreases in the time 
between your two images. Land cover changes 
in both space and time. Some of these changes, 
such as the process of succession in a wooded 
area, are natural. Others are “anthropogenic,” 
that is, produced by human beings. To determine 
whether these apparent changes are reasonable, 
use the substantial amount of data collected with 
the Land Cover Sample Site Protocol. The Land 
Cover Sample Sites that you visited will help to 
determine the accuracy of your land cover maps. 
If you find that you need more data than you 
have, simply use the protocol to collect more. 
For example, if your change image appears 
to show large increases in urban areas within 
your GLOBE Study Site, you will need to visit 
these areas to determine if this is really the case. 
Remember that some kinds of features appear 
very similar in Landsat images. Clouds, beach 
sand, and highly developed urban areas all appear 
similar, and may not be well distinguished. Since 
you are the experts for your GLOBE Study Site, 
you can use your own familiarity with the area 
to help you determine if the changes shown are 
reasonable.
What do scientists look for in these 
data?
Environmental scientists use land cover data to 
help develop computer models for everything from 
atmospheric circulation to the uptake of Carbon by 
different parts of the environment. Often, remotely 
sensed images are used to determine land cover. 
If the images used are not up-to-date, they do 
not provide accurate input to the models. Also, 
scientists must often estimate land cover types 
without visiting the area in question. Your data 
on land cover change can help scientists fine tune 
their models. These data are also very valuable to 
local community planners who are not always able 
to see change over as large a scale as you can. To 
adequately understand what has happened, and 
to help predict what may yet occur, scientists need 
to know what changes have occurred, and how 
much time was needed for those changes. From 
these data, rates of change can be calculated. It 
is rates and directions of change that help us to 
predict what may happen next.
GLOBE® 2005 Change Detection Protocol - 7 Land Cover/Biology
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Introduction
Protocols
An Example of Student Inquiry
Students in the Nashville, Tennessee, area were investigating change over time around the Nashville 
International Airport. They knew that during the time between their Landsat 5 and 7 images, the 
runways at the airport had been lengthened. This group created a computer-assisted land cover map 
of a portion of their 1992 image that included the airport. 
The group then created a map for their 1999 image of the same area.
GLOBE® 2005 Change Detection Protocol - 8 Land Cover/Biology
Examining these maps, they were certain that significant growth had occurred in the airport area over 
the time between the images. They used the Change Detection Tutorial to produce a change image.
The group found that the change image indicated development at the airport. They could see the change 
represented as the green areas at the ends of the runways, They were also interested to see that there 
were other areas of green, or change. They thought that this might indicate places where there was 
urban-type development. They knew that magenta (purple) areas suggest places in which there may 
have been a decrease in developed-type land covers. The MUC 91 areas (residential) showed this. The 
group wondered if that was due to the growth of trees around homes. They decided that they should 
visit these places to explore their ideas further. 


Land Cover Change Detection Protocol

http://www.globe.gov/tctg/land_prot_changedetect.pdf?sectionId=213

Land Cover Change Detection Protocol

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