Geographic Information Systems

Objectives

More on midterm
quick coverage of intended subject of last lecture
Introduction to GIS

Midterm

Results were announced at last lecture. Exams were handed back and discussed (occupying the whole of the lecture period). If you missed this event, please try to find a time off-line to discuss the results.

ANNOUNCEMENT

Management has decided to add a second part to the midterm. It is DUE 25 February. This is not intended as make-work, but to clarify the intent of the midterm in supporting the class objectives.

Introduction to GIS

A full lecture on GIS definitions from the Geog 460 class.

An accepted (bland) definition:

"A system of hardware, software, data, people, organizations and institutional arrangements for collecting, storing, analyzing, and disseminating information about areas of the earth." (Dueker & Kjerne, 1989)

Proposed in Exploring GIS

GIS: The organized activity by which people

measure aspects of geographic phenomena and processes;
represent these measurements, usually in the form of a computer database, to emphasize spatial themes, entities, and relationships;
operate upon these representations to produce more measurements and to discover new relationships by integrating disparate sources; and
transform these representations to conform to other frameworks of entities and relationships.

These activities reflect the larger context (institutions and cultures) in which these people carry out their work. In turn, the GIS may influence these structures.

Dane County Land Records Project (an early application of GIS)

(presented from outside in)

Social Context:

Society (politics, media, etc.) has become aware of soil erosion produced by farming practices.

Institutional:

Legislature created a mandate requiring counties to produce a plan to meet certain soil erosion goals by a given date.

Information component

1982: Most counties proceed using manual methods, in Dane County, University of Wisconsin attempts to demonstrate GIS (still experimental at that time)

Transformations:

Existing records must be made compatible. Soil erosion require six distinct 'layers' of information, measured differently.

Operations:

Overlay, primarily. (prediction of soil loss and possible changes in farming practices)

Representation:

Structure information resources to meet the objectives of the mandate. Unified spatial reference system had to be assembled, each source registered to a set of known points.

Measurement:

choices to obtain raw facts about environment to serve the purpose. Project relied on existing records: soils maps (many attributes attached to a set of zones), parcels, wetlands, etc.

Bottom Line:

Order of Magnitude improvements in geopositioning, automation, interpretation and processing

For further reading, begin with:

Niemann, B. J.; Sullivan, J. G.; Ventura, S. J.; Chrisman, N. R., 1987: Results of the Dane County Land Records Project, Photogrammetric Engineering and Remote Sensing 53, October, 1371-1378.

Version of 10 February 2000