GEOG 6N - Lab 2: Mapping Change Geographic Information Systems (GIS) were origin
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Question
GEOG 6N - Lab 2: Mapping Change
Geographic Information Systems (GIS) were originally created way back in the 1960s to analyze
relationships of phenomena across space and time. Sure, you could analyze spatial relationships
via paper maps or plastic transparencies, but that’s clunky (ever tried to fold a paper map back
into its original shape?). And what if you want to change the variables, or the way the data is
classified, or the map scale? A GIS gives you the flexibility and power to analyze lots of data
efficiently.
Changing Landscapes
One type of change that is evident all around us is physical change and demographic change in
our own communities. Think about your own community:
What has changed since you moved there? What forces are causing that change? How did your community look in terms of the people who live there and the uses of the land in your community 10 or 100 years ago?
How will your community look in 10 or 100 years? Could any of these changes be mapped? How do these changes compare in magnitude and scale from those changes in other parts of the world?
Unless you have been living under a rock since the 1950s, you know about space probes that
have been launched to observe the Moon, Mars, and other objects in our own solar system and
beyond. Since the early 1970s, satellites have also been launched specifically to observe the
Earth. Some observe oceans, while others observe agricultural health, atmospheric composition, weather, or other phenomena. The first of these was Landsat, short for “land
satellite.” Landsat became a series of satellites operated by NASA and the US Geological Survey
since 1972. Landsat observes the Earth in the visible and infrared portions of the spectrum. In
an infrared image, healthy vegetation appears red, cities appear gray, water appears black, and
other interesting colors appear as well. The point is not actually to create weird colors, but that
the infrared imagery allows for changes to be detected easily on the landscape, such as urban
sprawl, agriculture, deforestation, and fluctuations in water elevation.
Open a web browser and access the Esri Change Matters site:
http://changematters.esri.com/compare
Change Matters uses Landsat imagery and ArcGIS Online. You should see three side-by-side
web GIS maps, similar to the image below.
The first set of scenes is that of Mount St. Helens from 1975 and 2000. Use the information
provided in the link at the lower right "how to interpret a change image" if you need it, to
answer the following questions (you do not need to write these):
Describe a few changes you observe in Mount St. Helens from 1975 to 2000.
What do you think is the reason for those changes? Google about St. Helens if need be.
Using the search box above the images, enter "Aral Sea."
Describe the changes in the Aral Sea.
What do you think are the reasons for those changes? Do some more research if you need to.
Now, examine other places around the world using this resource. What does your hometown
look like?
Zoom in on one of the Change Matters image sets. The spatial resolution of Landsat imagery is now 30 meters x 30 meters (it was coarser in its earliest iterations). So, while you can’t see individual people using this resolution, you can detect large changes across the Earth’s surface.
To share a map from the Change Matters site: click on the green box icon at the top right of the
interface. That will give you a URL you can share, and those Twitter/Facebook buttons work
nicely too. Send a link to your parents to show them what you’re doing before they hear about
State Patty’s Day.
Scale Matters
Now, head over to this link on ArcGIS Online.
You are looking at the Northeastern Junior College campus in Sterling, Colorado. Click the
Content button at the upper left of the interface to see the map layers that you have at your
disposal. You should have Map Notes, USA Topo Maps, and Imagery with Labels.
Click on the pushpin at the intersection of the paths that form an “X” on campus. In the popup
box that appears, you should see some notes and a photograph taken on the ground. In a few
minutes you’ll create your own map notes and popups. Click on the photograph. You should be
directed to a new website.
What website was the photograph linked to?
Unlike the Landsat images, this satellite image was taken in the visible spectrum. It comes from
a satellite operated by DigitalGlobe, and it has a much finer resolution than the Landsat imagery. You could definitely use this stuff to count the number of dog turds in someone’s lawn.
What is the smallest object that you can see on the DigitalGlobe satellite image?
Now go to Bookmarks and select Sterling. You should now be looking at the town of Sterling,
Colorado, with the USA Topo Maps layer as semi-transparent. Earlier, you used a side-by-side
set of images to detect change over time. Here, using transparency on layers is another way
you can look at change over time. Click the small arrow next to USA Topo Maps in the list of
layers, click the ... and adjust the visibility of that layer by clicking on Transparency and then
dragging the slider around.
The USA Topo maps layer is a USGS topographic map; and in the case of Sterling, the map was
created in 1971.
Find two changes in the town of Sterling from 1971 to 2012.
Now examine the Northeastern Junior College Campus, comparing the current campus as seen
in the satellite image to the features on the 1971 topographic map by sliding the transparency
control back and forth for the USA Topo Maps layer.
What feature occupied most of the campus back in 1971?
Until now in our lab assignments you have been using maps and layers created by others. One
of the revolutionary things about today’s mapping methods is that you can create your own
content, save it, and share it with others quite easily.
You should have already received an email invite (sent to your PSU email **CHECK YOUR SPAM FOLDER** if you don’t see it) – follow the link in that message to set up your account. If you need help, talk to your TA.
None of this will cost you any money, result in 40 catalogs sent to your house or anything crazy
like that – it’s just a way for you to be able to upload stuff, save your maps, and share things
more easily.
Now that you are signed into ArcGIS Online, you can do everything that you have been doing
last week and earlier in this current lab exercise, but now you can save your maps. You can
build on them as you see fit. And because these maps live online, you can share them with
colleagues; you can embed them into your own web pages, you can create web applications
from them, and you can reduce your cholesterol by 30%. But let’s not get ahead of ourselves:
let’s begin with those pushpins, popups, and embedded images and links that you were
examining earlier by creating your own.
Navigate now to a different location in the United States that is of interest to you. If your map
still is titled “Northeast Junior College” then click on “New Map” to start creating a completely
new map. I would navigate to Princeville, Hawaii because it’s freaking awesome. Just as you
searched for layers in the previous lab, click Add and search for the USA Topo Maps layer. Add it to the map and compare it with the Imagery layer from the Basemap for your chosen
location.
Zoom to a location where you can observe change on the landscape between the topographic
map and the satellite image. Add a pushpin, some text, an image, and a link to a point by following these steps: Using the Add button, Add Map Notes and select Create. Give it a name,
but leave Map Notes as the template. Then select a point, line, or area from the Add Features
menu. Click on the map then to add your point, line, or area to the map. Fill out the popup box
that appears with the following:
An appropriate title.
A description of the changes on the landscape that you observe.
Find an image of that community or your chosen location and enter its URL in the “Image URL” box. You can get this URL by right-clicking an image on a website and clicking Copy Image Location. Note that this image URL should be a link to a JPG, PNG, TIF, or other image.
Enter an Image Link URL that will take the reader of your map to an appropriate website. The website could be the government site for that community, a local restaurant that you think embodies that place, or whatever else you see fit to use.
Exit the Add Features panel by clicking the Close button at the bottom right corner of the
popup. Test your popup by clicking on your map note. You should see your note title, text, and
image. Click on your image - you should be directed to the website that you selected.
Now go to Bookmarks and set up a few bookmarks at different locations and scales in your
chosen community. You can do this by clicking Add Bookmark in the Bookmark list, type in a
name, and hit Enter to save it. It'll use the map settings at that moment to make a Bookmark,
so you'll need to navigate, change your layers, etc... before you add a specific Bookmark.
Once you’ve added a couple map notes and bookmarks, save your map by clicking the Save
button. Give it an appropriate title. If you call it “Map” that’d be pretty lame.
In the Tags area you can enter keywords to help people discover your map. In the Summary
field you can write a short description about your map that will be helpful to the readers of your map. This is known as the map’s metadata—information about the map. It is sort of like
the list of ingredients on a bag of chips.
Why do you think it would be important to spend time adding metadata like this?
Next, let’s make your map viewable to others: using the Share button, share your map with
Everyone. Write down or copy the URL of your map to your clipboard. You can give this to
anyone and they’ll be able to load and use your map.
Now click on the ArcGIS in the top left corner of the interface and select My Content. You
should see your map listed in your content. In subsequent labs, your content will grow as you
create more maps.
Finally, let’s test your map: First, make sure you copied that URL for your map that you created
when you shared it just a minute ago. Next, Log out of ArcGIS online. Open a new web browser
frame. Add your map URL to the address bar in your browser and see if you can access your
map without being logged into ArcGIS Online. This is possible because you shared your map
with everyone in the step above. While you are in your map, test your bookmarks.
Take a screenshot of your popup and map like this. You will submit this screenshot and the URL to your map as part of the deliverables to this lab.
This map can be accessed at http://arcg.is/1hUMCLc
Examining Resolution
As you learned in the reading this week, different locations on the planet contain different data
at different resolutions. You saw a satellite image of Salzburg that featured two different
resolutions, and earlier in this lab, you saw that the USA Topo map resolution was at a lower
resolution than the imagery.
One reason why maps are noteworthy today is that you can easily create your own content.
And so can others - this is commonly called crowdsourced data or volunteered geographic
information. In the not too distant past, the only geospatial data providers were government
agencies and nonprofit organizations. Nowadays, everyone is empowered to create their own
data and share it. Esri has a program called the Community Maps program where folks can
contribute content to a topographic basemap.
Log in to ArcGIS Online and start a new Map if you aren't already there. Change your Basemap
to Topographic (it may already be set this way by default, that's OK too). Use the search box to
search for the following address: 1000 Broadway, Boulder, CO. You should now be in Boulder,
Colorado. Broadway is the street that runs from the southeast to the northwest across this part
of Boulder. Compare the detail to the northeast of Broadway to the map details shown to the
southwest of Broadway.
Which part of the map – to the northeast of Broadway or to the southwest of Broadway—contains a more detailed basemap?
What is the most detailed feature that is visible in the higher detail section of the basemap?
The highly detailed sections of this map were contributed to Esri through the community maps
program.
Projections Aren’t Just to Make Maps Pretty
Everything in a GIS is tied to a specific location on the Earth’s surface. All of those locations are
measured based on a mathematically-computed map projection. Recall from class where we
talked about why transforming stuff from the 3D globe to a 2D map requires some
transformation (and therefore compromises).
The map projection that you use makes a big difference in your spatial analysis. If you are
creating zones that consider Tobler’s First Law of Geography and want to determine which
things are near other things, you usually create areas of proximity, or buffer zones around map
features. These could represent the areas within 100 kilometers of the earthquakes of at least
magnitude 7 that have occurred over the past year, for example, or areas within 100 meters of
rivers in your local community. Those zones that you create, as well as everything else you do
and create in a GIS, are all dependent on the map projection used. Using different map projections will yield different results. The results might not matter so much at a small scale for,
say, the list of cities within a certain climate zone, but they would matter at a large scale to
determine, say, all of the natural gas pipelines underneath a school building that you would
need to be careful about when constructing a new library.
Now I’d like you to start a New Map, zoom out to show the whole world, and compare the size
of Greenland versus that of South America. Greenland looks larger than South America, doesn’t
it? Greenland is actually only about 12% as large as South America (~2 million square kilometers
vs. ~17 million square kilometers). Why does Greenland look huge? The default projection in
ArcGIS Online is a modified version of a Mercator projection. In the Mercator projection,
latitude and longitude lines are conveniently shown as straight lines and it allows us to plot
navigational directions in straight lines. But as you can see, objects near the poles are really
distorted.
Next, expand the Home list in the top left corner and click on Groups. Groups are, as the name
implies, sets of maps with a specific theme. Click on the Search box in the top right corner and
select Search For Groups and then type Projected Basemaps into the search field before hitting
Enter. You’ll now need to uncheck the “Only search in Penn State University Dept Geography”
at the top left of the interface. The results list will now refresh and show you a set of choices.
Click on the Projected Basemaps group name by user cfitzpatrick to open this group and you
will see two pages of projected basemaps. Browse these basemaps and open a few of them.
Each is based on a different map projection. Think about the advantages and disadvantages of
each projection. The map projections represented here are just a few of the thousands of map projections that exist. Why so many? Each projection has advantages and disadvantages. Each
projection preserves some, but not all, of the following properties: Area, shape, direction,
bearing, and distance.
Wrap Up
Nice work! In this lab you’ve examined issues of resolution and map projection. You also
explored issues related to change detection in Geography. And you created your own map with
your own content and shared it with others. That’s awesome.
Required deliverables for this lab
Make a single Word or PDF document with the following things and submit it to the Lab 2 assignment dropbox on Canvas:
Address this question in a thoughtful paragraph: Which map projection in this group
would offer special advantages for visualizing tsunamis in countries bordering the Pacific
Ocean? Why?
Address these questions in a thoughtful paragraph: In what ways might an unscrupulous
map maker use projections inappropriately to support a certain cause? Which of the
projections in this group could be misused in this way, either intentionally or unintentionally?
Submit a screen capture of the map you saved above on Page 6, also making sure to
include its URL somewhere in your submission. To get full credit, the screenshot should
show at least one map note with the popup box open. For example: "This map can be accessed at http://arcg.is/1hUMCLc" Your TA will open this link to check your work. Your map must be original apart from anyone else's in the class.
Grading Rubric
Your lab reports will be graded using the following rubric:
Quality – the degree to which your answers are carefully thought and well-reasoned
0 – None of the answers are carefully thought and well-reasoned
1 – Only a few answers are carefully thought and well-reasoned
2 – Some of the answers are carefully thought and well-reasoned
3 – Most of the answers are carefully thought and well-reasoned
4 – All answers are carefully thought and well-reasoned
Clarity – the degree to which your writing is clear, concise, and grammatically correct.
0 – The report is impossible to read
1 – A large number of clarity issues are present
2 – A fair number of clarity issues are present
3 – A small number of clarity issues are present
4 – The report has no clarity issues and is easy to read
Completeness – the degree to which your report contains all of the required elements as
directed in the assignment
0 – None of the required elements were included
1 – Only a few of the required elements were included
2 – Some of the required elements were included
3 – Most of the required elements were included
4 – All of the required elements were included
Explanation / Answer
What has changed since you moved there? Answer: Agricultural lands were reduced and replaced by concrete buildings and factories. Vehicles increased which led to cutting of trees for laying roads leading to air pollution and change in climate. What forces are causing that change? Answer: Employment opportunities that attracted people to settle down, increase in the sale of vehicles which prompted people to buy and use, cheaper rates of lands that were available to occupy due to loss of water and reduction in agriculture use. How did your community look in terms of the people who live there and the uses of the land in your community 10 or 100 years ago? Answer: Our community has changed a lot in terms of serenity and peace. Once a silent area has become a noisy factory and crowded vehicles have contributed to polluted air mass. Water levels in the groundwater has reduced and water scarcity increased forcing the wildlife to reduce in numbers or to change their habitat. How will your community look in 10 or 100 years? Answer: It may almost become a desert if this is the rate of occupation of area and utilization of natural resources like water. Increasing air pollution may force the community residents to buy oxygen and oxygen masks to breathe. Wildlife may hardly be heard or visible alive. Could any of these changes be mapped? Answer: Yes. Ground water levels, changes in urban expansion, population growth, green coverage, temperature changes, climatic changes can be mapped.
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