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Maps have been used for thousands of years, but it is
only within the last few decades that the technology has existed to combine maps
with computer graphics and databases to create geographic information systems or
GIS.
GIS is used to display and analyze spatial data which
are tied to a relational database. This connection is what gives GIS its power:
maps can be drawn from the database and data can be referenced from the maps. When
a database is updated, the associated map can be dynamically updated as well. GIS
databases include a wide variety of information: geographic, social, political,
environmental, and demographic.
GIS uses layers, called "themes," to overlay different
types of information, much as some static maps use mylar overlays to add tiers of
information to a geographic background. Each theme represents a category of information,
such as roads or forest cover. As with the old mylar maps, the layers which are
underneath remain visible while additional themes are placed above.
Services
ESS combines orthorectified satellite images and digital
aerial photography mosaics with extracted vector and client supplied attribute data
and hot links, using ESRI?s ArcView GIS, ArcGIS and ArcGIS 3D Analyst Project files,
in support of GIS Based Products:
Raster to Vector Translation
To complement the mapping functions included in GIS and
other Mapping and Data processing software, vector data is utilized to facilitate
the visualization of surface and subsurface features. To assure that the vector
data, to be extracted from Digital Satellite Images, Aerial Photo mosaics or digital
map data, is free of any Coordinate ambiguities outside of the Project specifications,
all Satellite Image data and Digital Aerial Photography is orthorectified.
Topographic, Geological or any other type of source maps
are rectified, utilizing at least 75-100% of the available grid ticks on the maps.
Final vector data can be provided in a variety of formats,
like AutoCAD DWG or DXF, ESRI Shape files, standard ASCII X, Y, Z or Client requested
format and referenced to specified Survey Datum and Mapping Projection.
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