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TRIAD for
WINDOWS
Survey Retracement & Analysis Software
Typical
Applications
BOUNDARY
RETRACEMENT - When a retracement
of a previous survey is required, existing monuments must be verified
and lost monuments replaced. If a map or deed exists for which
some corresponding monuments have been found then it is possible
to analyze how the found monuments relate to the map. A field
survey is performed locating existing monuments from which coordinates
are calculated for the monuments. The map may be calculated on
some arbitrary coordinate system based on the record bearings
and distances. This establishes map coordinates at the corners
and verifies the mathematical correctness of the map. The fieldwork
and the map are now available on unrelated coordinate systems
with a dual set of point numbers for common locations. All of
the points from the unrelated systems are combined in a coordinate
data text file.
Run the Triad
program and enter the point numbers of corresponding locations.
Triad will pair up the coordinates of the map points with
the coordinates of the found monuments and instantly find the
best fit for rotation, scale, and translations. The solution for
the transformation will indicate the best rotation between the
map and the field survey and the best scale factor to be applied
to the map distances that correspond to the field measured distances.
You may then analyze the residuals, use the error detection routine,
reject bad monuments, and re-process the solution as necessary.
After a solution is determined that represents the best retracement
of the survey, Triad can create new points by transforming
all of the points from the map to the field survey coordinate
system. Alternately, the field coordinates may be best fit to
the map.
CORNER
SEARCHING - In the course of a BOUNDARY RETRACEMENT, as
described above, it may be helpful to use the found monuments
to develop search areas for monuments not yet located. Triad
will allow you to estimate the accuracy of the search area from
the Radial Standard Deviation.
PUBLIC
LAND SURVEYS - Triad can be used in the retracement
of sectionalized lands to determine the proportional length of
the government chain and the deviation of the compass (known as
indexing). This may be very useful for estimating the proximity
for corner searching. Note, calculate the map (plat) coordinates
in chains then the resulting scale factor determined by the program
will be equivalent to the length of the government chain.
GRANT
BOUNDARY ADJUSTMENT - Triad automatically performs
a Grant Boundary Adjustment as described in the Manual of Instructions
for the Survey of Public Lands when new points are calculated
that begin and end at two fixed points in a solution. Triad
will rotate, translate, and proportionately adjust record measurements
in the same manner as prescribed for public land surveys.
GPS
& CONVENTIONAL CONTROL SURVEYS -
Adjusting field measurements to fit existing control points without
verification may distort good work. Avoid this by computing a
minimally constrained adjustment of the field measurements to
obtain preliminary coordinates. Then, use Triad to fit
these coordinates to the published or accepted coordinates of
found control points to verify consistency and check for problems
before performing a constrained adjustment.
SUBSIDENCE
& EARTH MOVEMENT - Establish a control network outside
of the study area on stable ground. Perform a field survey from
time to time locating the monitoring points to track subsidence
relative to the outside control network. Using Triad, fix
the outside control and set the monitored points inside the study
area free. Compute a transformation solution to fit earlier observed
positions to later observed (new positions) of monitored points.
The actual movement of the monitored points will be indicated
by the residuals.
DATUM
TRANSFORMATIONS - Use Triad to compute local transformations
in state plane coordinates from the North American Datum of 1927
(NAD27) to North American Datum of 1983 (NAD83). Assuming sufficient
common control points, this will provide an accurate and quantifiable
solution (better than Corpscon).
GIS
- Use Triad to create a mosaic of parcels by hooking subdivision
maps and boundary surveys together via common points. Then, constrain
the composite mosaic to best fit known ground control.
Triad
can determine the positions on a best fit straight line for a
row of monuments.
SYSTEM REQUIREMENTS:
SYSTEM REQUIREMENTS: WINDOWS 95, 98, ME, 2000, XP & NT - PURCHASE
PRICE $445.00
COPYRIGHT 1990-2002 MCGEE SURVEYING CONSULTING
Tel. 805-964-3520
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