Introduction
| Technical Overview | Partners
General Overview
The United States Geological Survey (USGS) has funded
several The
National Map projects across the nation. Most
recently the USGS funded a project that addresses the
cooperation and collaboration necessary for developing
the capabilities and functionality of a fully implemented
National Map. This project will test some of the technology
and functionality of developing The National Map on
a regional scale.
Open GIS Consortium
Web Mapping Service (WMS) 1.1.1 implementing wrappers
will be developed and distributed to the cooperating
partners. The partnering agencies will serve up their
data through the web mapping service and the data will
be seamlessly displayed in a {single/common/the Interoperable
GeoObserver} map viewing client using consistent
style representation and symbology.
This project will focus on the interoperability of serving
geospatial framework data through a distributed network
of servers. Emphasis for this project will be put on
serving statewide content of four themes of data: Transportation,
Boundaries, Hydrography and Orthoimagery. Each of the
themes will be unique to each state. For example, the
transportation theme may have been developed by the
Highway and Transportation Department in Arkansas and
the U.S. Bureau of the Census in Missouri.
Each cooperating state institution will be responsible
for maintaining their geospatial data, installing the
WMS wrapper on their server, hosting the web-mapping
service and providing server support, as well as assisting
with the semantic mapping of their data for appropriate
display and symbolization.
The Arkansas Geographic Information Office will work
with the Center for Advanced Spatial Technologies, Kansas
Data Access Support Center (DASC), Missouri Spatial
Data Information Service, Distributed Active Archive
Center, and the United States Geological Survey throughout
the course of this project.
Technical Overview
Technical Lead Shane Covington,
The Center for Advanced
Spatial Technology
Currently many web sites allow users to display and
browse geospatial data through the use of map viewers.
However, most of these sites only allow geospatial data
to be displayed which is stored and served within the
context of the map viewer. The OpenGIS Consortium's
Web Map Service (WMS) Implementation Specification (http://www.opengis.org/techno/specs/01-068r3.pdf)
allows any map viewer implementing the WMS interface
to display maps from map servers which also implement
this specification.
OpenGIS Consortium Web Map Services allows map viewers
to display geospatial data throughout the world. The
advantage of interoperability are numerous, but the
biggest advantage in a regional collaboration is geospatial
data can be seamlessly displayed from different state
or regional authorities in a manner which allows users
to feel like the geospatial data they are viewing comes
from the same source. Because of interoperability, geospatial
data can be warehoused at authoritative organizations
which have the most precise data temporally, spectrally,
and spatially. This capability allows users to view
the most accurate and up to date feature data on a regional
scale even though the displayed features come from different
sources. For example, geospatial data warehouses for
individual states can be used in collaboration to display
similar feature types (e.g. roads) in a seamless manner
across state boundaries. This is accomplished by requesting
map images from two map servers of bounding states which
only warehouse their state's data.
OGC's Web Map Service Implementation defines parameter
name-value pairs to request map images in a common manner
in order to overlay map images from multiple map server
to produce a seamless map. This is possible when map
images are requested that have the same bounding box,
image size, and spatial reference system. The transparency
of the image is also very important because it allows
map images to be overlaid within a map viewer.
Additional information can be reviewed at http://ogc.cast.uark.edu/tnm/
Introduction
| Technical Overview | Partners
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