Introduction to ArcView
You will NOT be able to do this exercise at home
on your own time. I will distribute data sets in class, burned onto
CD-ROMs.
students have previously opened this page.
Please be on time, if you are late it will be very difficult to catch up and you will waste time of those students who are punctual.
ArcView is the benchmark GIS (geographical information systems) platform. GIS means information system (database!!) that is geo-referenced - that is, the elements of a GIS involve locations (points), linear features (highways, streams) and/or polygons (enclosed areas). A great deal of information is now distributed as GIS projects. Today and next week we will learn some of the basics of working with a GIS project prepared by someone else.
If you wish to learn how to set up your own GIS based on field surveying you yourself are doing, sign up for EEES 3030 - Physical Environmental Laboratory (aka Environmental Data Management). This is not currently scheduled but will be taught if there is a demand for it - see me and see Dr. Phillips. The Department of Geography & Planning offers several GIS courses, albeit with more of a focus on social science applications than on physical science applications.
There are several projects I would like to supervise as independent study or senior thesis for anyone interested in learning more about ArcView. See me after the final exam or early next autumn.
Today we will learn to maneuver and manipulate a View.
Upon opening ArcView, we select "Open an existing project" and navigate to the "F" drive (CD-ROM drive) - in the "data" folder click "2500". Projects have the extension .apr in ArcView.
In testing a CD-ROM, at this point I got a message asking for the location of one of the files - I hit "Cancel all" and View 1 appeared on the screen.
A view consists of a set of themes or layers. You can turn a theme on or off by clicking the box to the far left in the Legend. You can select a theme by clicking on that theme in the Legend. You can select several themes by clicking additional themes while holding down the shift key.
Zoom tool: looks like a magnifying glass. There are also buttons to zoom to full extent, zoom to theme (the selected theme), zoom in, zoom out, and, zoom to previous extent (very useful when you zoom and get a really unwanted result). Note - there is no "undo" button.
Classifying data: The instructor will demonstrate how to view the theme table and how to display ranges of attributes based on numerical values. For example: populations of departments, surface area of departments, population density of departments. There are several ways of classifying - Dr.D. will explain these briefly - please pay attention! Classifications can be displayed as graduated color or as graduated size - each has its place.
Adding themes to a view: In the View menu, Add Theme - locate the theme earthquakes.shp (the extension .shp indicates an ArcView shapefile, the fundamental vector element of an ArcView theme.
Note on data types: ArcView can display geo-registered images, shapefiles, and locations based on a database table. Images are raster data - rectangular arrays of numbers that the computer converts into colors, each color occupying a square whose size is defined by the resolution of the image. This introduction will not get into image or raster manipulation.
The fundamental vector location is the point. In this application, each point is defined by its latitude and longitude. A line (or arc) connects a series of points and has a direction - point where the line begins and point where the line ends. A polygon is a line where the first and last points are identical. Because elements of shapefiles are stored as mathematical representations, their spatial attributes can be measured and new shapefiles generated based on relationships between shapefiles.
Classifying data
Opening a shapefile table
Query in shapefile table
"Save (selected elements) as" new shapefile
All earthquakes are not equal. Once the earthquakes.shp theme is part of your view, classify the earthquakes with respect to size (magnitude). Make the big earthquakes really big, the small earthquakes really small. Use the "identify" tool to display the parameters of the biggest earthquakes. When did they strike, and what were their magnitudes?
Information button
Select button
Next, classify earthquakes according to depth. Is there a pattern to the distribution of shallow vs. deep earthquakes?
Minimize your View and you should see this page:
Layouts: turning your views into images for other applications. Minimize View window, select Layouts. Essential buttons are in lower toolbar, at the right-hand end of the bar.
Saving projects.
To do: Discover the answers to the following questions and send me the answers by e-mail.
What is the number of your CD-ROM?
Which are the most heavily populated (highest population density) departments in the 4 nations covered here?
When did the largest earthquakes strike this part of the world? Month, day, year - and magnitude (compile a short list). When did this earthquake catalog begin and when did it end?
How would you interpret the pattern (if any) of depth distribution of earthquakes?
Keep your CD-ROM and bring it to class next week. Do not lose it! Do not forget it!! You may leave it with me in my office (please bring it to my office when I am in so I can record your turning it in) and I will bring it next week, if you so wish.