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MICRO GIS must be structured through the use of more accurate data
input and are usually used to develop "action plans". This data is
often gathered for smaller geographic areas. Users of this type of
data are utility companies, intensive land management groups, engin
eering designers and construction organizations. These GIS's consist
of data that is provided by using accurate large-scale maps and
appropriate scale aerial photography. Output from these systems are
usually large-scale strip maps, utility facility placement maps, earth
work volumes, etc. Examples of these systems are the Texas Department
of Highways and Public Transportation's Highway Design Systems and
Southwestern Bell Telephone Company's Automated Mapping and Facility
Management project.
THE ANALYTICAL PLOTTER IN THE MICRO GEOGRAPHIC DATA BASE STRATEGY
The analytical stereoplotter can be used in the data gathering phase of
MACRO systems, but it is not usually used because the data does not
need to be accurate and can be gathered more economically by utilizing
data that may already be in a computer compatible form. In MICRO
systems the analytical plotter is the most economical system to use as
a gatherer. The analytical plotter can provide data that is accurate
and designed to fit the MICRO need. The broad steps In gathering these
data are:
o Determining Needs - The data base requirements are stringently
determined to satisfy the final use. These requirements will
determine the scale, elevation accuracies, and other special
needs such as the digitizing of light and power poles, manhole
covers, etc.
o Planning to Meet Needs - This step involves research of
available material such as maps to determine accuracy, content,
etc., available aerial photography, and control. After this
research, required planning is done to acquire aerial photog
raphy and field control to fill the gaps in the existing
information.
o Acquisition of Needed Data - Existing, useable maps, and other
information is purchased in a stable base-scaled media. Aerial
photography is flown and field control is performed. All
materials are inspected and properly ordered for use.
o Digitizing - Coding of data needed is designed to fit the GIS
and CAC to be utilized. This will set special requirements on
how the data is to be digitized - by layers, point features,
etc. This menu of codes for various features digitizing will
be the stereoplotter-digitizer operator's bible.
From Maps - Digitizing from maps will be done on a table
capable of sensing positions by use of an electronically
sensitized surface. Features will be traced and in the
process, the features will be converted to data in
necessary format.
From Aerial Photography - This is the digitizing process
that makes the analytical stereoplotter so powerful.
Digitizing from aerial photography that is properly
controlled also provides the most accurate and uniform