Technical Assistance
GIS/GPS Mapping
types of GPS equipment
There are three grades of data collection equipment: survey grade, mapping grade
and commercial grade. The survey grade equipment maintains an average of ¼-inch
accuracy and costs $50,000 to $60,000. The mapping grade equipment maintains an
average of 12-18-inch accuracy and costs $5,000 to $15,000. Commercial grade
equipment can be purchased at most outdoor supply stores, maintains an accuracy
of 30 to 90 feet and costs $75 to $500. KRWA field staff utilizes mapping grade
equipment, set up for data collection. KRWA's equipment has an acceptable amount
of accuracy for the type of data collection involved.
GPS equipment used
KRWA uses the Trimble® GeoXH to collect data in the field. The GeoXH handheld is
Trimble's top of-the-line solution for high accuracy GPS data collection.
Engineered with H-Star technology, the GeoXH handheld delivers the sub-foot (30
cm) accuracy required by electric and gas utilities, water and wastewater
services, land reform projects, and other applications where on-the-spot
positioning is crucial.
The unique GeoExplorer series combines a Trimble® GPS receiver with a rugged
handheld computer, built for all-day use.
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The GeoXH handheld comes with a powerful 416 MHz processor, running the most
advanced operating system available -- Microsoft® Windows MobileT Version 5.0
software for Pocket PC. Windows Mobile is the industry standard open platform
for mobile devices. Windows Mobile Version 5.0 features familiar Microsoft
software, including Pocket Word, Pocket Excel, and Pocket Outlook®. This
provides KRWA all the tools needed for a seamless exchange of data between the
field and the office. With increased security features and persistent memory
storage, you can be sure your data is safe once it's been collected.
Software
KRWA owns several different software packages for the purpose of collecting data
and post-processing that data in order to achieve the highest accuracy possible
for the most affordable cost. ArcView 9.1 is the package that allows KRWA to
create the GIS to the utility's specifications. ArcView allows a technician to
include different layers in the creation of the GIS. Aerial photography, parcel
IDs, road center lines, streams, boundaries, and any other layers of information
that are available can be included in the utility's GIS. Before the layers are
'stacked', the data that was collected in the field is post-processed. This
procedure is performed by the software package GPS Analyst/GPS Correct and
allows for increased accuracy by contacting known base stations via the Internet
and comparing the known coordinates of those base stations and the recently
collected data from the field. This post processing reduces the error in data
that may have occurred in the field from uncontrollable events such as weather,
ionic disruption or satellite signal loss. ArcPad is the software platform that
is utilized on the GeoXH in order to interpret and log the data that is being
received from the satellites. All of these software packages are necessary to
collect and improve the data in order to facilitate the production of the
digital GIS and the maps that are printed for the utility.
