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Non-Road Boards => Off-Topic => Topic started by: bandit957 on June 07, 2014, 12:14:12 PM

Title: Converting NAD83 to lat/long?
Post by: bandit957 on June 07, 2014, 12:14:12 PM
Does anyone here know the formula for converting NAD83 coordinates to latitude and longitude in degrees? The Internet doesn't seem to have it.
Title: Re: Converting NAD83 to lat/long?
Post by: corco on June 07, 2014, 12:56:07 PM
NAD83 is just a datum, not the projection so NAD83 could be in lat-long or something else. What do the coordinates you have look like?
Title: Re: Converting NAD83 to lat/long?
Post by: bandit957 on June 07, 2014, 01:00:13 PM
Quote from: corco on June 07, 2014, 12:56:07 PM
NAD83 is just a datum, not the projection so NAD83 could be in lat-long or something else. What do the coordinates you have look like?

For a certain point within the city of Cincinnati, the X and Y coordinates are 1404800 and 450892.1875. I'm using a list of points within the city of Cincinnati.
Title: Re: Converting NAD83 to lat/long?
Post by: corco on June 07, 2014, 01:44:16 PM
Okay, they're state plane then. Two ways to do it:

One by one: http://www.earthpoint.us/stateplane.aspx
1404800 is the X, 450892.1875 is the Y, the zone you want is 3402 Ohio - South and the units in US survey feet.

Batch: http://www.earthpoint.us/batchconvert.aspx
and then follow those instructions

The math to do it yourself in Excel gets to be pretty tricky- conceptually I understand how it works, but to actually devise the formula I'm not even entirely sure how to do it.
Title: Re: Converting NAD83 to lat/long?
Post by: PHLBOS on June 09, 2014, 01:42:42 PM
This site (http://www.ngs.noaa.gov/PC_PROD/pc_prod.shtml) has downloadable programs that allows one to convert state plane coordinates to lat/long & vice-versa.
Title: Re: Converting NAD83 to lat/long?
Post by: Roadrunner75 on June 10, 2014, 08:59:23 PM
Quote from: PHLBOS on June 09, 2014, 01:42:42 PM
This site (http://www.ngs.noaa.gov/PC_PROD/pc_prod.shtml) has downloadable programs that allows one to convert state plane coordinates to lat/long & vice-versa.

I use Corpscon at work for conversions, which is a free download on that site (NGS).  It's easy to use and works well.