ArcView and GMT – An Introduction to Two Simple GIS Systems

Bill Langin

EAS 781

9/18/02

GIS Systems?

- GIS (Geographic Information System) is used loosely, as neither of these programs is nearly as powerful as Arc/Info, the most powerful GIS out there…

- ArcView may be close, but I haven’t explored it’s full capabilities and extensions (like most people, once I got what I needed out of it, I didn’t really explore the other functions)

- GMT has no “interactive” mapping/information capabilities, at least that I know about

- Arc/Info’s baby brother

- Don’t confuse with newer ArcGIS

- not as popular, easy to use

- Department site license

- can freely be put on any machine in the department, including your personal machine (see Aaron)

- Several useful data sets provided

- county, state, and country borders

- rivers, lakes

- lat/lon grids

- many more…

ArcView (v. 3.2)

http://www.esri.com/

Getting Started w/ ArcView

The “View” Window- The main working window in ArcView

The “Tables” Window- Click on add and you can add any table saved as a .dbf file to the project

Adding Themes

- Use “Add Theme” under the View Menu to add ESRI themes, images (geocoded), or converted ArcInfo coverages.

- Use “Add Event Theme” to add a theme based on data from one of the tables that was added to the project.

- After adding the theme, you can edit the properties by double clicking on it in the view window.

Editing Themes- In theme window, double clicking on the theme will bring up the theme editing window. You can then edit the type of symbols used, colors, classifications, etc.

View after adding “themes”

Where types of themes are there?

-“Pre-loaded” themes (ESRI Data, found in c:\esri\esridata)

- Tables

-create tables in Excel

- save as DBASE 4 file (*.dbf) file

- Geocoded TIFFs

- ArcInfo coverages

ArcView Demo

GMT – Generic Mapping Tool

- Official web site: http://gmt.soest.hawaii.edu/

- freely available for download

- UNIX, LINUX, Windows, MAC

- I’ve got it running on UNIX and Windows, I have not tried the other platforms

- Developed and maintained by Paul Wessel and Walter H. F. Smith. 

Official GMT Description“GMT is a free, open source collection of ~60 UNIX tools that allow users to manipulate (x,y) and (x,y,z) data sets (including filtering, trend fitting, gridding, projecting, etc.) and produce Encapsulated PostScript File (EPS) illustrations ranging from simple x-y plots through contour maps to artificially illuminated surfaces and 3-D perspective views in black and white, gray tone, hachure patterns, and 24-bit color. GMT supports 25 common map projections plus linear, log, and power scaling, and comes with support data such as coastlines, rivers, and political boundaries.”

- GMT website

The Basics…- GMT is a set of ~60 or so commands that take input arguments and files and produce post-script images

- Command line driven – UNIX, DOS friendly

- It takes a day or two to learn the basics, but the online help is pretty good

- Very useful if used in shell scripts (ex. C-shell, BASH, perl, etc.)

Some Examples of GMT output

-examples of figures created using GMT and the commands that produced them can be found at:

http://gmt.soest.hawaii.edu/gmt/gmt_examples.html

GMT Demonstration