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is there anyway to convert a legal description of a property to gps figures


daltonman

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There is no easy way to do a property survey using simple GPS equipment. If there was, most of us land surveyors out here would be out of business! You could hire a local land surveyor to survey the property in question, using survey-grade GPS equipment and post-processing software, and tying in to your local grid system, and then have him convert his calculated coordinates on the property corners to Lat/Longs, which you could then enter into your handheld GPS. But I don't think that is what you had in mind. Sorry!

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First, be aware that any numbers you might be able to derive from the legal description using any information you get from here are likely to be suspect at best. They'll definitely not be good enough to precisely locate a property line or a property corner, even if your GPS receiver were 100% accurate, which it isn't. That said, you're really asking two different questions.

 

The first question is, how do you convert that "northwest corner section 3, township 31N range 3W p.m. 3" or whatever to lat/long coordinates (that's a bogus example; for all I know I've got it all mixed up.) In some parts of the country, you can find section boundaries on your topo maps. In some even more limited parts of the country, your topo maps will be marked with the township and range numbers, but if you know the postal address of the property you can probably figure out which section it is on the topo map without translating the township/range/PM stuff. You can scale halfway decent coordinates off of the topo map. If you need better coords than you can get from a topo map, you're probably using them for something you shouldn't be. If by some lucky happenstance the described point falls on a section corner, you can get pretty good coordinates for the section corner from USGS PLSS files, available for free in DLG and SDTS formats and readable by finer GIS software everywhere (but no more accurate than if you scaled it off the large-scale topo map yourself.)

 

Okay, so now you have a corner. From that corner, following the rest of the legal description is just like doing an offset cache or a letterbox, except that, IIRC, the bearings at each point are given in terms of your heading from the previous point.

 

Again, I have to stress that knowing this is not terribly useful in terms of locating the actual corners of the property. Your best bet on that score is if a real surveyor buried iron pins at the corners, as they are wont to do. Even then their location doesn't mean anything, legally speaking, but they'll give you a pretty good rough idea of the corners.

 

Of course, if you're looking for this cache, well, you'll have to figure out the township/range/PM stuff, and I've used up my quota of "helping people on that cache" for this year.

 

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http://www.firstam.com/faf/dimensions/home.html

 

Incidently, I was looking at buying a 2 acre parcel over the summer and the two boundary stakes away from the road were hidden by 3 foot high weeds. I wanted to see if some trees were on the property or not. I was able to find both using the plat drawing and my Merigold. Using waypoint projections, the GPSr put me within three feet of one stake, and right on top of the other.

 

I believe that the absolute accuracy (day to day location of any given point) of the GPS is withing 3m at 95%CI, but the relative accuracy (from one point to the next, with the same satellite geometry and atmospheric conditions) is much better.

 

Sure, the Merigold can't do accurate surveying, but if you have an accurate plat drawing, you should be able to locate the boundaries fairly accurately.

 

Dave.

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I'm not a surveyor, so this may not be completely correct, but this is how I understand how bearings work...

 

On the plat drawing I have, one leg of the property line is described as : S 88 46' 30" E 300

 

Bearings are based on quadrants, NE, SW, SW and NW. Zero degrees is at due North and South, with 90 degrees at due East and West. For the above bearing, it's in the SE quadrant, which starts at zero degrees due south and ends at 90 degrees due east. So S 88 E is translated to a conventional bearing of 92 degrees. I assumed that the bearings are true, not magnetic.

 

It helps to visualize the directions on the drawing.

 

In the above example, the 300 is 300 feet.

 

So I find one corner of the lot, and project a waypoint of 92 degrees and 300 feet and start walking.

 

Hope this helps. Do a GOOGLE search on 'bearing survey'. You'll find lots of information.

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