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Old April 11th 05, 06:19 PM
KBH
 
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The free software FAA software compsys21 will do this and more

That's interesting but for something the size of half-a-state I would
more likely work with UTM coordinates and then use plane survey
formulas...


Why use an inaccurate approximation when better software already exits???


You give yourself away with a comment like that...

Projections to rectangular grids are not intended to be approximations but
are intended to be rectangular grids.

Latitudes and longitudes labeled on an atlas are first converted to
rectangular coordinates, plotted as rectangular coordinates, and then
labeled as latitude and longitude. In other words any point (within range)
has both latitude / longitude location and UTM grid location. Simply there
is a conversion between the two.

Okay, UTM and geodetic have different directional orientations. But in
project layout any point is relative to two or more other points. In project
layout there is no such thing as one point relative to only one other point
because that would be a magical creation. The point is that UTM directional
orientation is used with UTM points and that geodetic directional
orientation is used with geodetic points. (For example, the consumer GPS
user can do this by getting their GPS location, getting a GPS location of a
skyscraper or transmission tower that can be seen in the distance, and then
laying out an angle to a required point using their home point location and
the line of sight to the tower. Note the three points and that is project
layout.)

Also, a bearing in UTM is one direction to the point. And that is likely
what is required on a project. A geodetic bearing is simply a beginning
direction to the point and directional corrections are required. That may be
okay for navigation but would very strange in project layout...So a layout
in UTM is a rumb line while a geodetic layout is a great circle. Note that a
point laid out on a rumb line in a UTM grid could after layout be converted
to latitude and longitude. In other words simply meet requirements and
output in any required format.

Of course for higher accuracy, projections to state plane coordinates are
used instead of UTM coordinates. And state plane coordinates are used
extensively in project layout. There are not a bunch of engineers walking
around saying "...why use an inaccurate approximation..." as the project is
simply defined with a rectangular coordinate system.

Finally, one benefit is using rectangular coordinates are that simple
formulas can be used with rectangular coordinates. Someone with an
inexpensive scientific calculator can make on-site calculations that for
instance a construction crew might be waiting on. And of course a $90 HP48
will hold and quickly run all of the plane survey formulas and will fit in
shirt pocket. Furthermore, plane survey formulas can be developed for PC
programs in short periods of time and without access to highly developed
formal sources of information or expertise.

So if the project is defined with rectangular coordinates why have a
software that does not apply to the task ?