MICRODEM: GIS & Mapping Visualization Peter L. Guth Department of Oceanography U.S. Naval Academy Annapolis MD 21402 pguth@usna.edu

Introduction

My background began as a structural geologist/field mapper, but for 15 years I've taught in an oceanography department at an undergraduate institution. Before that I spendt three years in a department of geography and computer science, where I began my work in computer graphics and mapping. My research has centered around the MICRODEM GIS program, which has been evolving since 1984 (Guth and others, 1987). This program has been particularly strong in military GIS (it forms the basis of the Army's TerraBase II) and geologic applications (Guth, 1988), and has been applied to a number of other applications: spatial analysis of DEM error (Guth, 1992), slope and aspect algorithms (Guth, 1995), contour line ghosts in DEMs derived from digitized contour lines (Guth, 1999), eigenvector extraction of terrain fabric (Guth, 2001, 2003), and the computational parameters of the line-of-sight algorithm (Guth, 2003, 2004). The engine has also been used for web delivery of terrain visualizations (Thibaud and others, 2002; Guth and others, 2003).

From the start MICRODEM emphasized a simple, graphical interface. It now consists of about 220,000 lines of Delphi source code. While the military supplied much of the impetus and funding for the program, it has always maintained a strong earth science focus. In addition to MICRODEM, this essay will include examples from a number of visualization programs I have written for teaching oceanography. These share code and techniques with MICRODEM. All the programs uses Borland's Delphi and run on the Windows platform. My bias leans toward software development used in teaching and my research.

This essay borrows from Guth (1997). It shows a number of animations from lab programs I have written, to demonstrate graphically how computer graphics can bring the earth sciences to life. The animations shown here use lower graphic and color resolution for improved download over theWWW; they run significantly better on a local PC. Local usage also allows student interactions and manipulation of the parameters of the animations.

Role of Animations and Visualizations --Visualization Examples Index
	Tell Stories: this type of visualization depicts a relationship. With an animation, it can show how the relationship changes over time. This extract from the annual cycle shows the relationship between earth tilt and the June solistice (Seasons & Climate).
	Explore and Understand Data: this type of visualization offer students the chance to manipulate and view complex data sets. Time series in the earth sciences provide one good example of this type of visualization. The diagram at the show shows an extract from over 250 profiles measured from the dunes and across the longshore bars at Duck, North Carolina. (Beach Profiles) While this may be similar to story telling, data exploration allows students to change the display, select parameters, and observe the changes.
	Animate an Equation: this animation shows the relationship betweeen wave period, speed, and water depth, and their affect on the wave group's speed. Students can adjust the various parameters used in the equation, and see how they affect the results.

GIS

GIS relates data and maps. Any data that has a geographic component--essentially all of the earth sciences--benefits from GIS. The power of GIS lies in the ability to filter and query the data--restrict what will be displayed based on any criteria of interest, and to go rapidly from the map to the data. Furthermore, interactions with the GIS can occur graphically on the map

Microcomputer Labs

A well-designed computer lab serves five teaching goals. First and foremost, a lab should teach or reinforce key concepts from lecture. A lab that does not advance one of the course’s major objectives should not be used. Secondly, labs can show the variability in nature. Textbooks and lectures usually employ “cartoon” figures and diagrams that show an idealized version of nature. Computer manipulation of actual data lets students see a variety of examples and develop an appreciation for how well the model fits the messy reality of nature. Third, the computer should encourage critical thinking and problem solving. Open-ended problems rather than cook book procedures force students to think about how they will use the computer as a tool to answer the question. Fourth, the lab will reinforce computer skills, something students will need in a technological world. Finally, the computer can reinforce writing across the curriculum because it removes the tedium from data analysis and visualization and lets students concentrate on understanding the processes involved and putting that understanding into words.

In designing my labs, I try to incorporate three fundamentals: avoid cookbook style exercises, maximize self-directed inquiry and problem solving, and provide hands-on and minds-on activities. I seek to provide a program that offers a set of tools to analyze data or a problem, and let the students decided which approach to use to answer a set of questions. Usually multiple approaches will work, because earth science data sets are typically multidimensional. As an example, the analysis of temperature in the Pacific Ocean becomes a five dimensional problem (latitude, longitude, depth, time, and temperature values) and we can easily display no more than two or three at a time. Students must learn the different ways earth scientists use to study such a problem, using map or profile views, colors, or contour lines.

Custom Programming

A good custom program requires a large commitment in time, effort, and maintenance. The learning curve to become proficient in programming, especially with event driven Windows programs, can be very steep. I have been programming almost as long as MS-DOS and Windows computers have been available, and have incrementally been upgrading the programs. When I started there was no educational software for the earth sciences, and there are still no commercial programs available for many of these functions. The available programs often prove less than fully satisfactory. Custom software can maximize the hardware capabilities in our labs and that our students have in their rooms.

Windows provides a common look and feel to programs, so that students can anticipate what to do (watching students use the program will often suggest better ways to handle the user interface). Each program has an integrated help file, and in addition to providing context sensitive help on demand, the help files offer hypertext instruction complete with graphics, indexes, and jumps to related topics. Window allows support for hardware, especially printers; common tools like text and graphics editors; and easy export of graphic files to other programs.

MICRODEM GIS

MICRODEM can be downloaded from the WWW. The help file is about 15 MB in size, and contains a number of tutorials, exercises, and graphics demonstrating the capibilities of the program.

GIS Alternatives

Alternatives to MICRODEM include GMT (Wessel and Smith, 1991, 1998) or commercial software like ArcView from ESRI. While GMT remains a reseach standard in the geophysical community, its UNIX heritage with a command line and complex parameters does not work well for students. GMT is free. Other workers (Hall-Wallace and McAuliffe, 2002; Saguaro Project) have chosen to work within the confines of commercial ESRI software, which imposes a cost in both dollars and learning the complex interface. In addition, while ESRI software can be enhanced by the end user, it will never be as easy to customize for geoscience applications as MICRODEM.

Web GIS

I've also done some work with delivery of GIS graphics over the internet. There are a number of issues with this approach:

• IT organizations are not comfortable with the security issuesof individual faculty running CGI programs with database access and reading and writing of files on the servers. From the IT organization perspective, it doesn't really matter whether you want to try to set this up on their hardware, or your hardware connected to their network.
• Most commercial web servers also will not let you run this type of application on their hardware; you will probably require a dedicated system.
• The large data files required for GIS operations have large download times, and in most cases I think local programs will provide the best response times for students. Many of the labs I use require several 100 MB of data files. As a one time download this is reasonable, and the response time thereafter is very fast.
• The user interface for a web application is much more limited than a Windows program, and porting the user interface to the web produces a large part of the required effort.

See Guth and others (2004) for an description of web delivered GIS. You may also be able to run a live web demonstration involving the location of forest fires (this site is generally open for testing, but you should read the disclaimers). Both of these applications use the mapping and GIS core from MICRODEM.

References, Cited & Un

• Guth, P.L., 1988, Microcomputer-assisted-drawing of geologic cross sections: Mathematical Geology, vol.20, p.991-1000.
• Guth, P.L., 1992, Spatial analysis of DEM error: ASPRS/ACSM/RT 92 Technical Papers [American Society for Photogrammetry and Remote Sensing/American Congress on Surveying and Mapping/Resource Technology 92, Washington DC, Aug 3-8, 1992], vol.2, pp.187-196, 1992.
• Guth, P.L., 1995, Slope and aspect calculations on gridded digital elevation models: Examples from a geomorphometric toolbox for personal computers: Zeitschrift für Geomorphologie N.F. Supplementband 101, pp.31-52.
• Guth, P.L., 1995, Personal computer labs for physical oceanography: Current The Journal of Marine Education, vol.13, no.1, pp.21-22.
• Guth, P.L., 1997, Teaching plate tectonics and marine geophysics to introductory students with a microcomputer: Journal of Geoscience Education, vol.45, no.5, pp.451-455.
• Guth, P.L., 1997, Computer Simulations and Graphical Data Manipulations for Teaching Earth Sciences, in Teaching and Learning in the Next Century, Essays from a Conference for the Federal Service Academies, held at West Point 27-28 September 1996, p.17-27.
• Guth, P.L., 1999, Contour line “ghosts” in USGS Level 2 DEMs: Photogrammetric Engineering & Remote Sensing, vol.65, no.3, p.289-296.
• Guth, P.L., 2001, Quantifying terrain fabric in digital elevation models, in Ehlen, J., and Harmon, R.S., eds., The environmental legacy of military operations, Geological Society of America Reviews in Engineering Geology , vol. 14, p.13-25.
• Guth, P.L., 2003, Terrain Organization Calculated From Digital Elevation Models: in Evans, I.S., Dikau, R., Tokunaga, E., Ohmori, H., and Hirano, M., eds., Concepts and Modelling in Geomorphology: International Perspectives:  Terrapub Publishers, Tokyo, p.199-220.
• Guth, P.L, 2003, Ambush Movies and the Weapons Fan Algorithm: Military GIS Operations and Theory, in Proceedings of the International Conference on Military Geology and Geography, June 15-18, 2003, West Point NY, HTML published on CD-ROM.
• Guth, P.L., 2004, The Geometry of Line-of-Sight and Weapons Fan Algorithms: Perspectives on Military Geology and Geography, Caldwell, D., Ehlen, J., and Haron, R. (eds.), Kluwer, publication in summer 2004.
• Guth, P.L, Olaf Oertel, Guillaume Bénard, and Rémy Thibaud, 2003, Pocket Panorama: 3D GIS on a handheld device: in Bertolotto, M., ed., Proceedings of the Third International Workshop on Web and Wireless Geographical Information Systems  (W²GIS 2003),  Dec 13, 2003, Rome, p 92-96.
• Guth, P.L., Ressler, E.K., and Bacastow, T.S., 1987, Microcomputer program for manipulating large digital terrain models: Computers & Geosciences, vol.13, no.3, p.209-213.
• Hall-Wallace, M.K., and McAuliffe, C.M., 2002, Design, implementation, and evaluation of GIS-based learning materials in an introductory geoscience course: Journal of Geoscience Education, vol.50, no.1, p.5-14.
• Johnson, M.C., and Guth, P.L., 1997, A realistic microcomputer exercise to teach geologic reasoning: Journal of Geoscience Education, vol.45, no.4, pp.349-353.
• Johnson, M.C., and Guth, P.L., 2002, Using GPS to teach more than accurate positions: Journal of Geoscience Education, vol.50, no.3, pp.241-246.
• Thibaud, R., F. Brugiere, P. Clad, and P. L. Guth, 2002, "Target3D: Interactive Visualization over the World Wide Web",  Second International Workshop on Web and Wireless Geographical Information Systems  W²GIS 2002, 11 Dec 2002, Singapore.
• Wessel, P. and Smith, W. H. F., 1991, Free software helps map and display data: EOS Trans. AGU, vol.72, p. 441.
• Wessel, P. and Smith, W. H. F., 1998, New, improved version of the Generic Mapping Tools released: EOS Trans. AGU, vol.79, p.579.

Presentation for "Teaching Geoscience with Visualizations: Using Images, Animations, and Models Effectively" Carleton College, Northfield, MN, 26-28 Feb 2004

Last revision 2/18/2004