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GIS FOR A SMALL CITY USING GPS & PHOTOGRAMMETRY 
Kandiah Jeyapalan 
Professor of Civil Engineering 
Michael Byrne 
Major, U.S. Army 
lowa State University 
Ames, lowa U.S.A. 
ISPRS Commission number IV 
Abstract 
This article will highlight the procedures used in one approach to create an 
automated GIS for a small city to include development of the base map. The paper 
will show the efficiency in using GPS surveying to establish ground control as well 
as the integral role photogrammetry plays in the development of GIS. The 
significant amount of time to build the nongraphical attribute data base will be 
pointed out as well as suggestions to shorten the time involved in this task. The 
paper shows an automated GIS can assist in the operation of a small city as well 
as a larger city. 
Key Words: Geographic Information Systems, Surface State Plane Coordinates, 
Global Positioning System 
Introduction 
A Geographic Information System (GIS) should 
be able to provide the graphic display of a 
location, information on the location, analyze this 
information, and also relate this information to 
those of other locations. One very broad 
definition of a GIS is that it is a facility for 
preparing, presenting and interpreting facts that 
pertain to the surface of the earth (2). According 
to this definition manual or cartographic maps 
can be classified as a GIS (1). In both 
automated or manual systems, a base map 
providing the geographical reference to all 
information is required. A base map for a city 
must show spatial information such as utilities, 
building outlines, property boundaries, contours, 
etc. and nongraphical attribute data pertaining to 
the graphics (See fig. 1). In light of this, the 
essential elements a GIS must have (1): 
1. the capability to acquire data. This is the 
process of identifying and gathering data 
pertaining to the application. 
2. the capability to preprocess data. This is 
the process of putting all data into a 
format for entry into the GIS. 
3. capability to manage data. This is the 
process of creating and providing access 
to the data bases while providing for 
security. 
4. capability to manipulate and analyze data, 
which is a process of creating new data 
from existing data. 
5. capability to generate output products, to 
produce a soft copy (on screen) or a hard 
copy in a particular format. (See figure 2.) 
Commercial GIS software packages have 
different capabilities and features. One of the 
more important and distinguishing features of a 
software is its spatial data structure. The data 
structure affects both the storage volume and 
627 
processing efficiency of the system. The data 
structure of the software will determine which 
data base one might import for use in GIS. 
These are two major categories of spatial data 
structure: raster and vector. In raster 
structures, a value for the parameter of interest, 
land cover type for example, is developed for 
each picture element (pixel) within the limit of 
the area of concern (1). A line would be stored 
as a series of pixels lined up together from the 
starting to the ending point. Satellite remote 
sensing data are processed in a raster structure. 
Vector data structures are based on the locations 
of basic entities such as points, lines and 
circles. A circle might be stored as a center 
point with a radius in a vector structure, whereas 
in raster structure the circle is stored as a series 
of pixels that form its perimeter. Some GIS 
softwares can process both types of data 
structures. 
In the GIS application for cities knowing specific 
location and lengths of features are important 
and almost all spacial features of concern are 
linear or polygons bounded by straight lines. 
Since UltiMap, a vector data structure software, 
possesses both characteristics, it is suitable for 
developing GIS for cities. 
One of the primary requirements for developing 
a GIS for the city is a coordinate base map. 
When a coordinate base map is developed by 
digitizing existing city and subdivision maps, 
many systematic and random errors may result 
because these maps may themselves be second 
or third generation maps having errors from 
previous drawing or reproduction. The paper on 
which these maps are printed may have 
contracted or expanded causing further 
inaccuracies. Other errors may also result when 
the operator places the cross-hairs of the 
digitizing puck on the point or from the electronic 
capabilities of the digitizing hardware. In order 
to overcome these problems, modern GPS