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Phase 1: 2000
Aerial Photography
Project
(Status:100%
Complete):
On March
17, 2000 Western Air
Maps (WAM)
flew Vanderburgh
County, Indiana.
This produced black
and white aerial
negatives at a NCS
appropriate for
ASPRS Class 1
for
1-inch = 100-foot
planimetric mapping
and a two-foot
contour interval.
Aerial photography
was exposed at 3960'
+/- above mean
terrain. This
warranted a nominal
negative scale of 1"
= 660-foot and which
produced 1-inch =
100-foot scale
digital ortho images
with a 6" pixel
resolution. This
means that each
pixel within an
image represents 6
inches on the
ground.
Triangulation
for control was
accomplished by
fully analytical
methods. Positional
accuracy (vector of
both northing and
easting coordinate
errors) of pass
points established
by triangulation was
sufficient to
support digital
photogrammetric
feature accuracy
requirements
outlined by ASPRS
Class 1 standards
for a map scale of
1-inch = 100-feet.
Planimetric mapping
was also produced
with ninety percent
of all well-defined
features (except
control points) were
positioned on the
finished digital
maps with an
accuracy of at least
+/- 2-feet of their
true coordinate
position, and such
that none of the
features shall be
misplaced by a
relative value of
more than 4-feet.
This also produced
2-foot contours with
ninety percent of
the elevation points
determined from the
contours having an
accuracy of 1-foot
or better with
respect to true
elevation, and spot
elevation accuracy
of 0.5-foot or
better with respect
to true elevation.
Phase
2: Vanderburgh
County Parcel
Conversion and
Street
Centerline
Conflation
Projects (Parcel
Status:100%
Complete; Street
Centerline
Status 100%
Complete):
Parcel
Project: Vanderburgh
County encompasses
about 77,613 parcels
onto approximately
2750 paper maps of
various scales and
accuracies. During
the 2001-2002 Parcel
Conversion Project,
these paper maps
were converted into
digital parcel lines
that meet one-inch
equals one hundred
feet mapping scale
which suggests an
accuracy of +- 2ft.
All horizontal
coordinates are in
survey feet in the
Indiana State Plane
Coordinate System
(SPCS) West Zone
(1302) North
American Datum (NAD)
1983. Descriptive
information about
the parcels
(attributes) are
collected, entered,
and maintained by
each individual
Township Assessor.
Street
Centerline Project:
During the 2000
Aerial Photography
Project, over 13,000
street centerlines
were captured at an
accuracy of +/-
2-feet. These
centerlines were
highly accurate
geographically, but
did not contain
street information
like address ranges,
street name, street
type, etc. This
information was
contained in a
national dataset
like TIGER that was
created by the
Bureau of the
Census. The problem
with the TIGER
dataset was that it
was geographically
off by hundreds of
feet which is
insufficient for
critical
applications like
911, Emergency
Planning,
Engineering, etc.
The first
step in the project
was to automate the
process of
transferring the
street information
(attributes) from
TIGER to the highly
accurate street
centerline layer
from the 2000
photography. This
was done through a
software process
which tremendously
reduced staff hours
and achieved
approximately a
seventy to eighty
percent success
ratio. Currently
this dataset is
being thoroughly
looked at (scrubbed)
by Central Dispatch
and will go through
a series of tests to
check its
accuracies. After
tests have been
performed, this
local dataset will
be implemented into
the new 911 system
which brings several
advantages for the
residents of the
City/County. Some of
these include the
following:
- Highly
Accurate
- Maintained
by local
government
departments.
- New
streets are added
quickly and by the
departments that
are responsible
for address
ranges.
- Once new
streets have been
added, the 911
system is updated
right a way which
would not be the
situation with
national datasets.
This
dataset will also be
the base in which
Census boundaries
like Tracts, and
Blocks will be
recreated to more
accurately represent
Evansville and
Vanderburgh County.
Once these
additional layers
are corrected, they
will be re-submitted
to the Bureau of the
Census to be forever
part of future
Census releases.
Phase
3: Utility
Infrastructure
Project (Status:
Beginning
Stages):
