Parcels can form the basis of a GIS but they are
often difficult to map and maintain. The level of accuracy is the
most important factor in determining the method of mapping parcels
and the costs.
Mapping parcels is possible
by scanning existing paper assessor maps. This is the easiest, but
quite a bit of accuracy is lost. The most accurate, and therefore
expensive, method is to draw the lines using survey coordinates (coordinate
geometry also known as COGO). It is possible to map parcels using
an intermediate method, perhaps initially scanning available paper
maps then over time use COGO to improve the accuracy.
The cost of creating a
parcel coverage depends on the accuracy required. A technician might
create five parcels an hour using the COGO method, but this assumes
all the surveys, plats, and other legal information is readily available.
Inevitably conflicts will occur, neighboring parcels might have unwanted
gaps between them or they might even overlap. Resolving these errors
Once a parcel coverage
is built, maintenance is generally straight-forward. A GIS application
can automate updating and improve the accuracy of any new parcels.
A GIS or cadastral technician would maintain the parcels using a mouse
instead of pen and ink. The technician would use a set of GIS tools
built specifically for maintaining parcels. The technician is thus
free to concentrate on updating parcels and doesn't have to know anything
about GIS programming.
Creating and maintaining
parcels using a GIS is the most efficient way to keep property information
updated and secure. A stack of paper maps is prone to damage or loss.
Computerized data is routinely backed up and kept secure. How much
would it cost you to recreate all your paper parcel maps in the event
of a catastrophe?
128 N 2nd Street Yakima, WA 98901