Lesson 1: Navigating an ArcIMS Web Page
This lesson
was created and is copywrited by Vince Formica. All opinions expressed are solely his, and do
not reflect the opinions of Dr. Tuttle,
Lesson Goals:
1) Learn what a GIS is, and why ArcIMS pages are
important
2) Learn the major frames and components of an ArcIMS
page
3) Learn to Navigate in a web page created by ArcIMS
using the tool bar
4) Gain some insight into the theory of the science of
GIS
What is GIS?
GIS traditionally stands for Geographic
Information System, but recently as GIS becomes more quantitative and model
driven researchers and journals have begun to call GIS Geographic Information Science.
The book definition that the USGS (United States Geological Survey) uses
is:
“In the
strictest sense, a GIS is a computer system capable of assembling, storing,
manipulating, and displaying geographically referenced information, i.e. data
identified according to their locations. Practitioners also regard the total
GIS as including operating personnel and the data that go into the system.”
A simple
definition:
“GIS is a
way for looking at and comparing many different layers of spatial data.”
Why is it useful?
“Knowing where things are and why is essential to
rational decision making.”
-Jack Daggermond
(President of ESRI)
What can we do with this
great technology? If you want thousands
of great examples go to ESRI’s web page (ESRI is the
company that makes ArcView, the most common GIS software). But common uses are:
Ø
Research Ecology
Ø
Crime Tracking
and Analysis
Ø
Industry
Planning
Ø
Social and
Government Planning
Ø
Environmental
Planning
Ø
Emergency Search
and Rescue
Basically, GIS software is a
really fancy graphing program. Simply
put, GIS software takes X and Y coordinates (e.g. latitude and longitude) and
by plotting these coordinates, GIS software makes features that have geographic
positions. What makes GIS so powerful is
that we can attach data to these geographic features. Not only do where know where a water tower
is, but contained within the same program, we know how much water is in the
tower, and when the last time the tower was serviced. By attaching data to geographic positions we
can increase the level of our analysis and our planning. But enough with theory, as we learn how to
use GIS we will learn how important it is.
What is ArcIMS and why do
I need to learn how to use a web page that was created by it? :
ArcIMS is a software program
that allows GIS data to be displayed on a web page, and it allows anyone with a
web browser the opportunity to interact with the data in a way never before
possible. You have probably been exposed
to something similar to this if you have used any of the internet mapping
services such as MapQuest, or Yahoo Travel. The GIS data and the software program ArcIMS
is stored on a server at
Knowing how to use an ArcIMS
page is important, because it is very probable that in the future many GIS sources
will be posted in this format, or one very similar to it. In fact, both the EPA (Environmental
Protection Agency), and the USGS (United States Geologic Survey) use ArcIMS
like pages to display their GIS data.
Both of these agencies use this type of web pages to convey what data
they have available for downloading.
Working with a Page
Created by ArcIMS:
When you open the
White-throated sparrow ArcIMS web page, your screen should look something like
this:
Each part of the web page
serves a purpose. For convenience sake,
I have numbered the parts of the page in the image below.
Hint: Do not use the Back
button or the Refresh button on your internet browser. ArcIMS has specific buttons for navigating in
this interactive map.
1 = Tool Bar
2 = Overview Map
3 = Layer List / Legend
4 = Tabular Data Frame
(although other things beside tabular data can be displayed here)
5) Map Frame
1) Tool Bar:
This is the most used frame of the IMS page.
Each small icon represents a button.
After you select a button, you can do many different tasks. They work very similar to tool bar in
programs like Abode Photoshop, or Microsoft Word. We will cover each of these buttons in detail
shortly.
2) Overview Map:
This is a small map of the entire study site at
Cranberry Lake Biological Station. The
overview map will always show the entire data set, even if you zoom in. There is a red box in the map, which shows
you what part of the data set you are viewing even when you are zoomed in.
You can use the overview map
for navigating around the larger map, but clicking in any part of the overview
map. This will center the main map frame
( 
) to wherever you have clicked in the overview
map. We will do this later, so don’t
worry too much about it now.
3) Layer / Legend Frame:
We will come back to this frame
in just a moment. In order to understand
this frame, you must understand a little about how a GIS works.
4) Tabular Data Frame:
This frame is where an IMS
page displays the tabular data that is linked to a spatial feature. As I mentioned before, the power of GIS lays
in the fact that spatial features such as points, lines, or polygons have
tabular data linked to them, and we can query and analyze that data using spatial
and statistical analyses.
This frame is also where an
IMS page will display messages and where you can change settings. For instance at some point you may want to
change the units in which your measurements are reported (e.g. from meters to miles).
That will be done in this frame.
5) Map Frame
This is simply where the
spatial data is shown.
Note: You can change the size of these
frames by clicking and dragging the lines that separate each frame. You may want to do this if some of the text
is cut off between frames.
What are map Layers, and
why are they important to GIS?
One of the most useful
properties of a GIS is that you can display more than one set of GIS data at
once. In the old days this type of
analysis was done using Mylar sheets (clear pieces of plastic) each sheet had
one theme drawn it, and then all the sheets were stacked, physically, on top of
each other, and you could see all of the layers. So in this case, the nests and the territories
would be on separate sheets of Mylar.
But in a GIS, all the layers
are displayed simultaneously on your screen.
For example on our IMS page you can see the nests (as little bird or
nests icons), male territory boundaries, and the vegetation classification base
map layer, all at once. By stacking
these layers we can complete all sorts of useful qualitative as well as
quantitative analyses. On an IMS page
the layers are stacked in the order that they are listed in the Layer
frame. In other words, the names on the
top of the list are the layers stacked on top.
To use the Layers Frame in
our IMS page, you simply check or uncheck the box next to the layer name. If a box is checked, then the layer is
visible, and if it is unchecked, then the layer should not be visible. Let’s turn off (make invisible) the
vegetation classification layer, this will reveal the
false color aerial photography below it.
To do this, uncheck the box next to the words “Categorized Vegetation Cover”.
After you make most changes
to any settings on an IMS page, you must click the Refresh Map button.
Your map should now look
something like this:
Some of the layers (aka. themes) have tabular data associated with them; these
layers are Nests and Territories. In
order to view or analyze the tabular data associated with either of these
layers, they need to be “Active” you can do that by putting a dot in the radio
button. By default the Nests layer is
active, for this lesson, make the Territories layer
active, by clicking in the white circle (aka. radio
button) before the word “Territories”.
Your Layer frame should look
like this:
Using the Tools in the
Tool Bar
In the section below I will
tell you the name of each button and briefly describe their uses, I suggest
that you “play” with each button to get a better feel for how each works.
I will present you with each
button in the order that they appear in the toolbar. If you want to see the name of a button (or a
short description of what it does), then leave your mouse pointer over the
button for a second or two and a short description will appear in a little
yellow box. Give it a try.
1) 
à “Toggle Between Layer List and Legend”
This button toggles
(switches) the Layer frame from list of the layers to a legend. This legend will show you little pictures and
colors of what each layer should look like.
Push this button to see what I mean.
The new legend frame should look like this:
2) 
à “Toggle Overview Map”
This button turns off the
overview map. And if you click it again,
the overview map will appear again. This
can be useful if the overview map is getting in your way.
or 
3) 
à “zoom in”
This button is pretty self
explanatory. You can click once in the
Map frame to zoom in one standard unit, or you can click and drag an area that
you want to zoom in to.
Note:
click and drag means that you click your left mouse button and hold it down, and
then you drag a box around the area that you want to see up close. While you are doing it, it should look like
this:
Notice, that in the overview
map, the red box has gotten smaller, showing you that you are only viewing a
subset of spatial data. If you don’t see
your Overview map, click this button: .
Let’s try something else, in
the overview map, click somewhere outside of the red box. Notice, how your map frame
shifts to the place that you clicked.
4) 
à “Zoom out” button.
This button does the exact
opposite of the zoom in button.
5) 
à “Zoom to Full Extent”
Clicking this button will
cause an IMS page to zoom out so you can see all of the data on a page. Click it now and you will see how the screen
is zoomed to the same scale that you started with. If you are already zoomed out, then use the
zoom in tool to zoom in to a small part of the screen and then click the Full
extent button.
6) 
à “Zoom to active layer”
This button does the same
thing as the previous button, but instead of zooming to all the sets of data
that are in your map, it only zooms to the “active” layer. In our case it should be the territory layer. This can be useful if you have both regional
and local (large and small) layers on your page.
7) 
à “Back to Last Extent”
This button works similar to
the Back button in your internet browser, but instead of going back a web page,
it takes you back to you last zoom extent.
Let’s say that you have zoomed into a territory and you accidentally
click on the page, and zoom too close.
Instead of having to go all the way back out to the main map and then
zoom back in, you can just hit this button.
8) 
à Pan
You can use this button to
“grab” the map and move it however you want.
To grab the map simply click and hold the map frame and then move the
map in whatever direction you want to move, and then let go.
9-12) 
These pan arrows work in a
similar fashion as the pan hand, however they move in each direction a set
amount.
Suggestion: To
get used to how these zoom and pan buttons work. I suggest you zoom into different regions of
the map and try to navigate around to different territories and nests. If you get stuck, you can always hit the Zoom
to full extent button and that will take you back to the beginning extent.
Now you have the skills to navigate in an ArcIMS
page. The best way to really learn any software (especially GIS
software) is to “play” with it. By this
I mean that you should try to figure out what all the buttons do. Make up a project for yourself and try to
accomplish it. Perhaps the best way to
play while working with my lessons is to go back through the exercise and
complete it again, this time choosing different settings.
The next lesson will cover the rest of the tool buttons, the concept querying, as
well as exporting data to Excel.