# Land Survey with GPS



## wildboar6768

I have a Magellen Sportmap and was wondering if I had a plot map and/ r copy of a survey is it possible to find the corners of a parcel of land? Would the topo software help at all?


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## Muttly

I own a few different garmins, and the accuracy is generally 20-30 feet. close enough to estimate property corners very roughly, or to narrow down your search for property markers. The problem is that your survey is done in meeps & bounds off township section lines, and your GPS is using Lat/Long measured from the prime meridian and the equator, so if you could convert your m&b to lat/long you'd get close. the gazzeteer and topos have lat/long, but no property boundries. I have a friend who is a surveyor for consumers energy, and they use gps, and use either hand calcs. or computers to interpet data, but I know of no software readily avalible to the general public.


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## FishTales

Maybe some day the government will make it possible to download the plat maps with accurate GPS readings for the boundaries and property lines. 
But I don't see this happening in the near future.


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## TomW

Even if you had proper plot maps the accuracy of general public GPS equipment isn't good enough to do property boundry surveys. With WAAS enabled I think the best you can do is 3 meters. Survey companies have special receivers and calibration equipment that gets them down to inches but its very expensive. For this kind of accuracy you are really better off to hire a company to do it. 

Many counties have accurate digital plat maps available, but they are very expensive and require speciallized (GIS) CAD software to use. They are typically multi layered, and include a great deal of geographic as well as other data linked to the maps (population, voting precencts, school district boundries etc.) 

Take a look at the following link. I think there is some information about this available at some of the sublinks. 

http://www.doylesdartden.com/gis/

Tom W


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## fishnbasket2

There are too many variables involved with for someone to guess where their property lines are using a handheld GPS or grandpas transit. The reason you want to determine you property lines makes a huge difference, as well as where you are located. Usually you can tell if your property has been surveyed by looking at your legal description or tax description. If it reads Southwest 1/4 of the Southeast 1/4 of Section 4, it has not likely been surveyed. But if it has bearings and distances i.e. S 89d 39'53"E 550.25' or something to that effect, most likely surveyed. You could check at the register of deeds in the county the property is located in for a copy if it was recorded. If you don't find it at the registers office, start calling local survey companys. Most will not give you a copy if you are not the original client, but may retrace the survey and provide a copy of an updated drawing for a fee. If there has not been a survey on your property, call around anyway. You will usually get a better price if a company has done work in the section your property is located. 

On another note, just because a municipality has a GIS program or system does not mean the information is accurate. There is more to boundary surveys then the layman understands. Depending upon where you live, a small percentage of land has actually been surveyed. A lot of problems have been caused over time where attorneys and others have written a legal description without the benefit of a survey have made matters worse. A. GIS has its uses, and provides a pretty picture, but in most cases is far from accurate for determining boundary surveys.


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## dogjaw

The problem is basically in the gps unit itself. The US Forrestry Service uses a unit like on a boat, a large white dome attenna on top of a pole. This is mounted on a backpack, and extends above the person's head. These are used for marking boundries for logging. If gps was that accurate, surveyors would be using it instead of the conventional method. Gps is accurate within 30 feet. That means 30 *each way.* That's a 60 foot swath (are you 30' to the east, or 30' to the west of the mark). To prove the point, travel down the same path as before and see what your tracking shows. Typically, it runs parallel, even though your on the same path.


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## jjrobo

I cringe when clients tell me they were out there finding there corners with GPS, and I have seen some bad situations when loggers have used it. I've worked on a few survey jobs where it even went to court because somebody relied on there Garmin or Magellon to mark there line or corner. 

With that said, you can use it to get you "close" at times. But that is about it.

I actually just started working on a little project of my own where I am going to observe 30 or more benchmarks with know lat. and long. and see how accurate my Garmin is with and without WAAS. 

jjrobo


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## dogjaw

jjrobo said:


> I cringe when clients tell me they were out there finding there corners with GPS, and I have seen some bad situations when loggers have used it. I've worked on a few survey jobs where it even went to court because somebody relied on there Garmin or Magellon to mark there line or corner.
> 
> With that said, you can use it to get you "close" at times. But that is about it.
> 
> I actually just started working on a little project of my own where I am going to observe 30 or more benchmarks with know lat. and long. and see how accurate my Garmin is with and without WAAS.
> 
> jjrobo


Let us know how it turns out.


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## aborgman

dogjaw said:


> The problem is basically in the gps unit itself.


 In consumer GPS units, yes.



dogjaw said:


> The US Forrestry Service uses a unit like on a boat, a large white dome attenna on top of a pole. This is mounted on a backpack, and extends above the person's head. These are used for marking boundries for logging.


 Which is a GPS.



dogjaw said:


> If gps was that accurate, surveyors would be using it instead of the conventional method.


 They are... just not the $300 consumer GPS recievers.



dogjaw said:


> Gps is accurate within 30 feet. That means 30 *each way.* That's a 60 foot swath (are you 30' to the east, or 30' to the west of the mark). To prove the point, travel down the same path as before and see what your tracking shows. Typically, it runs parallel, even though your on the same path.


 GPS is accurate to whatever you're willing to spend money making it accurate to. GPS can be accurate to fractions of an inch. Some very expensive commercial GPS equipment has shown horizontal accuracies of +/- 5mm (~1/5") and vertical accuracy to +/- 2cm (~1.3").

-- 
Aaron


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## jjrobo

The GPS receivers that we use in surveying are very accurate. Whether er not they are more accurate than conventional equipment is always up to debate. The scale of the project has a lot to do with it. If you are surveying for many miles (ex. Cadilac to Grand Rapids), GPS is more accurate, but if you are in a relatively small area it may not be. 

Until recently we could not survey with just one receiver, you had to have more than one and do an adjustment back in the office. Even with one receiver you still have to be hooked up to a cell phone and dial into a server run by the state to get a fix that was accurate enough to use for surveying purposes. And for the price of one receiver you could pay a licensed surveyor for over 600 hours.


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## dogjaw

aborgman said:


> In consumer GPS units, yes.
> 
> 
> Which is a GPS.
> 
> 
> They are... just not the $300 consumer GPS recievers.
> 
> 
> GPS is accurate to whatever you're willing to spend money making it accurate to. GPS can be accurate to fractions of an inch. Some very expensive commercial GPS equipment has shown horizontal accuracies of +/- 5mm (~1/5") and vertical accuracy to +/- 2cm (~1.3").
> 
> --
> Aaron


You need to read the original post. A Sportmap was to be used. I referenced the fact that for more accurate readings, a different unit was needed (read my previous post). If you have more/different information, fine. Please don't put words in my mouth, or take them out of context.


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## fishnbasket2

jjrobo-

You must be a student in the the program at FSU. I Graduated in 1994.
25 minutes to the PM, Tippy ane the White near by. All those damn programs to write. Hope they change that part of the curriculum.


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## jjrobo

fishnbasket2......

Yes I am, never thought I would go to college. Finally decided that being licensed was the way to go. Hashimi is going to assign us are program any day now. I can't wait, lol... The curriculum is heading more and more towards programming. They just changed a bunch of classes this year. 

jjrobo


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## aborgman

dogjaw said:


> You need to read the original post. A Sportmap was to be used. I referenced the fact that for more accurate readings, a different unit was needed (read my previous post). If you have more/different information, fine. Please don't put words in my mouth, or take them out of context.


 Some of your words were just incorrect. I was correcting innaccuracies.




dogjaw said:


> If gps was that accurate, surveyors would be using it instead of the conventional method.


 Is an incorrect statement. GPS can be that accurate, and surveyors are using it instead of the conventional method.



dogjaw said:


> Gps is accurate within 30 feet.


 Is also an incorrect statement. His particular GPS may be accurate to only 30' but there is no inherent limitation in GPS which limits its accuracy to 30'.

I'm sure you know these things but what you wrote was unclear and gave the impression that several false statements were true. Just wanted to throw the info out there and correct those misstatements.

-- 
Aaron


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## wildboar6768

I was trying to get in the general vicinity of the area and then use a metal detector to locate the stakes in the ground.


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## fishnbasket2

jjrobo-

Good to hear you had the insight to go back and get the degree. Too many good people get screwed on pay because they don't have a degree and cannot get licensed. I was lucky to stumble on the program when I was making a final decision of what I wanted to be when I grew up. We had write at least 8-10 programs, Hash's being the worst. Good luck and it is worth it.


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## Hamilton Reef

When the river opens up a bit more I will use a GPS to find a lost corner marker in a remote area. In this case there is supposed to be a buried steel stake in the ground. Using a topo map and two known corners for references, the GPS76-MAP should ballpark me in close enough to find the post with a metal detector. I'll report back if the idea works.


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## fishnbasket2

You should be able to get "in the ballpark". Then start looking for flagging, old wood stakes, fence posts, tree lines, field lines, ect.


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## wildboar6768

How do you use the gps to "get in the ballpark"?


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## ESOX

The gps will tell you how accurate it will be at any given point in time. So if it shows you are on the spot you are looking for and says accuracy is at 20', you are in the ballpark.


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