[Proj] How to transform between NAD83 HARN/HPGN and WGS84

Landon Blake lblake at ksninc.com
Thu Feb 19 13:25:45 EST 2009


When you say NAD83 HARN are you using Colorado State Plane Coordinates?
Or are you dealing with lat/long values?

I don't think there isn't a huge difference between NAD83 and WGS84, but
I'd think Proj would have a conversion between the two.

If you are dealing with state plane coordinates a local surveyor can
probably point you to the conversion formulas that you need. Or you
might check with the state land surveying association in Colorado.

If you get stuck, let me know. I can bounce a message off a couple of
land surveying message boards with Colorado Surveyors listening.

Office Phone Number: (209) 946-0268
Cell Phone Number: (209) 992-0658

-----Original Message-----
From: proj-bounces at lists.maptools.org
[mailto:proj-bounces at lists.maptools.org] On Behalf Of Aaron Friesen
Sent: Thursday, February 19, 2009 9:21 AM
To: proj at lists.maptools.org
Subject: [Proj] How to transform between NAD83 HARN/HPGN and WGS84


I checked the archives for the past year and did not find an
answer to this.  Google did not provide me with any leads

I have data in NAD83 HARN for Colorado.  I need to take the
data into the field as WGS84, update it/add to it, and get
it back as NAD83 HARN for Colorado.  The data I am collecting
has sub-foot accuracy, so "close" is not good enough.

The information on the grid files does not address the
HARN/HPGN question.

Is this type of transformation with the accuracy I need
possible with Proj?

Are HARN grid files available or are towgs84 settings defined
for the various HARN areas?

Or am I stuck looking for an alternative, commercial solution?

Thank for your assistance.


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