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GeoCalc


fizzymagic
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Ever get tired of all the copying and pasting that is required to get coordinates from one program or Web page into another?

 

I've written a little Windows app that addresses the problem. It translates a variety of coordinate formats into other formats. I'll be adding other features as time goes on, including datum conversions, distance and projection calculations, etc.

 

For now, it takes a coordinate string in just about any format (including the geocaching.com format at the top of cache pages and UTM) and turns it into:

  • Decimal lat/long (DD.DDDDDD)

  • DD MM.MMM

  • DD MM SS.SS

  • UTM

Not Earth-shattering, but I find it useful.

 

Get it here.

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State Plane is ugly. Every state has its own rules as to what projection is used, what scale factor is used, and where the centerline is. In addition, most states have an older NAD27-based system that uses feet as units and a newer NAD83-based system that uses meters as units. There are programs that can do the conversion, but it's fairly ugly - especially if you're starting with the NAD27 kind of units.

 

pirate.cgi.gif

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For State Plane conversion, check out:

http://crunch.tec.army.mil/software/corpscon/corpscon.html

 

Here's a snippet:

quote:

Corpscon, Version 5.11.08 (Year 2000 compliant), is a MS-Windows-based program which allows the user to convert coordinates between Geographic, State Plane and Universal Transverse Mercator (UTM) systems on the North American Datum of 1927 (NAD 27), the North American Datum of 1983 (NAD 83) and High Accuracy Reference Networks (HARNs). Corpscon uses the National Geodetic Survey (NGS) program Nadcon to convert between NAD 27, NAD 83 and HARNs. Corpscon, Version 5.x, performs vertical conversions to and from the National Geodetic Vertical Datum of 1929 (NGVD 29) and the North American Vertical Datum of 1988 (NAVD 88). Vertical conversions are based on the NGS program Vertcon and can be performed for the continental U.S. only. Corpscon, Version 5.x, will also calculate geoid-ellipsoid separations based on the NGS program Geoid96. Geoid-ellipsoid separations can be calculated for the Continental U.S., Alaska, Hawaii and Puerto Rico/U.S. Virgin Islands.


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True north.

 

I am starting to think about magnetic north, but that is a whole kettle of fish again, since it is always moving. Thus, if you want to use magnetic north, you have to put in a model of the Earth's magnetic field and how it is changing, and then do the calculations based on where it is today.

 

Which means that you won't get the same answer two days in a row!

 

And magnetic north moves a lot: the declination changes several minutes per year in some parts of the US.

 

Your GPS does a very crude correction for magnetic north, to the nearest whole degree. But a precision of one degree for a projection kind of defeats the whole purpose of doing high-accuracy projections!

 

So there are a lot of issues, as you can well imagine! I hope that explanation helps.

 

[This message was edited by fizzymagic on September 06, 2003 at 12:21 AM.]

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Sigh, icon_frown.gif I am the 10% that doesn't get this one. I cut and paste coordinates into it and nothing happens. I tried the so-called solutions from the thread Getting Started:Address converts to coordinates. But nothing there looks like the numbers on the geocaching home page. Obviously missing something. This would be a handy tool if someone can straighten me out on it. Thanks.

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quote:
Originally posted by MotorBug:

I cut and paste coordinates into it and nothing happens. I tried the so-called solutions from the thread Getting Started:Address converts to coordinates.


 

If I had the faintest idea what you are talking about, I would try to help.

 

GeoCalc needs a single string containing coordinates in lat/long or UTM format. It doesn't do addresses.

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I've been thinking more about the magnetic north problem.

 

Which would people want more: a low-accuracy projection/distance using magnetic north, or a new tab to convert between WGS84 and NAD27? I know, I know, they are completely different things, but I am trying to figure out what's most useful.

 

If I do NAD27 conversions, I will probably use the technique used by most GPS units, which is a Molodensky transform. It has an accuracy of about 2 or 3 meters in the continental US, and is really not at all valid outside the US and US territories, although I can't imagine why anybody would want to use NAD27 outside the area covered by USGS topo maps. WOuld that be useful?

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Fizzy, some comments.

 

As for using it outside the continental US or more importantly out of the northern hemisphere it appears to give negative northings (easting is ok) for the southern hemisphere, which would indicate issues with false origins.

 

Correct coordinates (within proper ranges of minutes and seconds) are ok but it does some quirky things with minutes & seconds out of valid range.

 

My opinion with systems like this is they should prevent users from inputting out of range (incorrect) formats where users confuse one format to be another.

 

A quick example is say a latitude like 23 00.61' (assumed north), input as 23 00' 61" gives N 23 01.017' ( N 23 01' 01.00"), which is correct to a point but really shouldn't be allowed.

 

Where as if input as a southern latitude -23 00' 61", gives S 22 58.983', which indicates it's not applying the appropriate signs correctly as -23 00' 61" could (should but not entirely correct to do so) effectively be called -23 01' 01"

 

That's all I've had time to look at.

 

Cheers, Kerry.

 

I never get lost icon_smile.gif everybody keeps telling me where to go icon_wink.gif

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quote:
Originally posted by MotorBug:

Sigh, icon_frown.gif I am the 10% that doesn't get this one. I cut and paste coordinates into it and nothing happens. I tried the so-called solutions from the thread Getting Started:Address converts to coordinates. But nothing there looks like the numbers on the geocaching home page. Obviously missing something. This would be a handy tool if someone can straighten me out on it. Thanks.


 

Run GeoCalc

in the box labled "Coordinate String" copy and paste this

N 32° 39.513 W 097° 02.661

then hit the "go" button and watch the magic.

 

BTW Thanks fizzymagic

 

More rules = Less fun!

geocachingdb_button.giftexasgeocaching_sm.gifntga_button.gif

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quote:
Originally posted by fizzymagic:

Which would people want more: a low-accuracy projection/distance using magnetic north, or a new tab to convert between WGS84 and NAD27? I know, I know, they are completely different things, but I am trying to figure out what's most useful.


 

I'd vote for the conversion tab. As a benchmark hunter using a magnetic compass that's NOT adjustable for declination, I know the declination in my area, and I'm used to adding it to my provided data before dialing in the compass.

 

One thing I'd like to see (if you care, and assuming I'm not missing something), is the ability to project a point using dd mm ss.s. 98% of the time when I want to project a highly accurate new waypoint, I'm doing something like project a point 20.84 meters from origin @ 213° 47' 23.6".

 

Greg

N 39 54.705'

W 77 33.137'

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quote:
Originally posted by Kerry:

As for using it outside the continental US or more importantly out of the northern hemisphere it appears to give negative northings (easting is ok) for the southern hemisphere, which would indicate issues with false origins.


Oops. I'll fix that right away. It isn't supposed to do that.

 

*** Turns out I had the northing offset off by a factor of 10. Fixed.

quote:
Correct coordinates (within proper ranges of minutes and seconds) are ok but it does some quirky things with minutes & seconds out of valid range.

Thanks for pointing that out. I'll fix that right away. It will start rejecting coords with those out of range.

 

*** Fixed.

 

And I've put in the code to do DD MM SS or whatever for the projection, too. I am trying to decide if it would be worthwhile to format the forward and reverse azimuths that way.

 

[This message was edited by fizzymagic on September 08, 2003 at 09:44 PM.]

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Fizzy, one other thing I forgot, which is one of those which side of the fence issues with UTM and zones.

 

As you would no doubt be aware zones are 6 degrees wide with half a degree overlap.

 

I see that a longitude of say 156 00' 00" (as an example) can/could be either zone 56 or 57. Of course if someone was working with coordinates all in zone 56 (and that could include longitudes out to 156 30') then they might want the UTM coords to be in a specific zone especially for a zone overlap situation.

 

It appears that 156 00' 00" by defualt goes to the next highest zone (in this case 57). Is that your plan or do you have other thoughts on handling zone overlap issues?

 

Distance, Azimuth and Reverse Azimuth look ok.

 

Cheers, Kerry.

 

I never get lost icon_smile.gif everybody keeps telling me where to go icon_wink.gif

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quote:
Originally posted by Kerry:

As you would no doubt be aware zones are 6 degrees wide with half a degree overlap.


Yeah, I know about that. It accepts those coords as input, but it doesn't output them. I can't think of any way to implement the output portion here while keeping the interface simple. Of course, I should put the option into the source code, which you can get as well. icon_smile.gif

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quote:
Originally posted by fizzymagic:

quote:
Originally posted by MotorBug:

I cut and paste coordinates into it and nothing happens. I tried the so-called solutions from the thread Getting Started:Address converts to coordinates.


 

If I had the faintest idea what you are talking about, I would try to help.

 

GeoCalc needs a single string containing coordinates in lat/long or UTM format. It doesn't do addresses.


 

Sorry, I wasn't clear on what I was trying to do. In MS Streets & Trips, once I find an address, I use the location sensor feature to determine the coordinates. When I put those coordinates in GeoCal no conversion happened. Of course now it does work, so I was entering incorrectly.

 

Thanks, great program!

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quote:
Originally posted by MotorBug:

In MS Streets & Trips, once I find an address, I use the location sensor feature to determine the coordinates. When I put those coordinates in GeoCal no conversion happened.


I would be very grateful if you could let me know what that coordinate format was, and I can try to add it to those that GeoCalc will accept. I don't have S&T, so I don't know what they look like.

 

Thanks!

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fizzymagic, The MS Streets & Trips coordinates did work okay. I had messed up putting them in, probably without a comma between.

 

The format returned with the "location sensor" looks like 37.01234 North, 122.45678 West. The cursor works as the sensor, so you have to copy the numbers-- won't allow for a copy and paste, contrary to what I said originally.

 

Sorry for the confusion. Thanks again.

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