Landbase Maintenance What the future holds
Jay Clark
Geographic Data Technology, Inc.
11 Lafayette Street
Lebanon, NH 03766
The evolution of landbase mapping began with manual survey techniques.
Traditional thinking about landbases led to an assumption that they were static things,
similar to property surveys. For example, a crew could measure a service territory or,
better yet, get property surveys from local governments and keep them as reams of map
sheets. These sheets could then be duplicated and referred to in relation to the
engineering infrastructure, also carefully measured and drawn on paper.
In this mindset, landbase maintenance would be primarily motivated by changes in
the infrastructure. Unfortunately, an area the size of Dallas or Los Angeles would require
a small army of draftsmen to maintain.
Enter the CAD revolution.
With CDA systems, revisions could be made much more quickly, shrinking the
drafting pool, and making information-recall considerably quicker. Maintenance
procedures would still be driven by infrastructure changes. And data distribution would
still be primarily paper-based. Indeed, all assumptions behind CAD technology were still
"paper based". In CAD systems, for example:
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It's annotations, not attributes; street names are stored as text objects separate from
line work.
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Electronic storage and editing technology is only for preparing map sheets; data is
viewed on paper and analysis is done from paper.
Landbase data is principally for the use of the engineering group; the data collection
effort is leveraged only minimally for the rest of the enterprise.
The Paradigm Shift: GIS
Through the efforts of GDT's Don Cooke and others at Harvard Labs in the late 1960's,
the GIS revolution was born. This approach to electronic data storage defined the model
below:
Now we are able to assign many and varied attributes to the two nodes and the line
segment above, including elevation, feature names, addresses, feature class codes,
arterial classification codes, and anything else that the imagination offers.
With the development of GIS technology, the maintenance of the landbase diverged
from strictly a utilities infrastructure issue to an end in itself.
The United States Bureau of the Census made the concept of a nationwide landbase
a reality. Readily available and affordable, TIGER® data has provided a starting point for
many thousands of mapping projects. This data, available in the public domain, has
been the backbone of many an initial landbase development project.
