Land Surveyor

### Need help finding a good android gps app for boundary retracement.

I am looking for a good gps android app for doing boundary retracement.  Locate a position on first found corner and then enter direction and distance to establish waypoints to navigate through the woods.

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#### Replies

• Land Surveyor

Compute points in autocad 1 through whatever range (1- 999), export to your data collector, Go to the field find and collect 2 points on the ground in your state plane system, number them 1 = 2001, 2 = 2002. Translate your (1-999) group from 1 to 2001. Rotate your (1-999} group to your (2001-2002) group. old bearing 2001-2, new bearing 2001-2002) all computed points are now state plane in your area.  plot on georef aerial photo. Find an opening in the area of the point you are looking for set two points and traverse conventionally or measure as a baseline up and over to find the point.

• Good way to get a response, but I thought this was another " trick " ???. like solve a chord with just the Delta Angle. To many years with a compass I guess!!! and what kind of Boundary Retracement on a phone. I know your only using it for direction but what are you using to survey with.

I guess I am lost.

• sorry, I see you already answered this. but you might talk to William Robinson,

he knows a lot about these Apps. he is a member of this site.

• GeoEducator

Just recently I went to a rollout for a Total Station and I had asked that question. Currenty there apps that do just that, but they have an accuracy of 30 foot radius. So if accuracy is what you want you wont get it with an android app. It will only be as accurate as the cell itself. One way to test the accuracy of a survey type app is to mark out a known amount of feet, lets say 50 feet apart, ping the location of the first point, take the readings, and repeat the previous steps with the second point. Then do the math and you should be able to determine the accuracy of the app.

• Land Surveyor

hi john you can use  :

## Trimble GPS Hunt Pro

• Not a Surveyor

John,

I'm with Charlie on this one ... apps aren't (yet) the answer to everything.

The solution here pivots on GPS accuracy. Any app will be leveraging the GPS inside your phone which will be similar to your handheld GPS but the handheld (use Garmin) is a dedicated tool for doing exactly what you are trying to do (within certain accuracies) and like you indicated, will last all day and more importantly will not require a cell connection .. ie just because you can see yourself on an image in any app you may find, doesn't mean that you are actually at that spot. A newer handheld Garmin GPS will have the benefit of being able to leverage more satellites and WAAS which typically will give you more reliable accuracy.

It sounds to me that you don't have access to GIS/GNSS (sub yard) like the Trimble suggested previously or Survey grade (sub inch) GPS units so that would mean I'd suggest a newer handheld Garmin GPS and expect accuracy along a line to be within a couple yards of the line. If you need better accuracy, you need better gear ... and someone who knows how to run it along with the knowledge of the things that can go wrong.

Assuming only what you've told us so far: Next is to know where the line you are trying to follow actually is. I'm Canadian but I believe that what I'm going to tell you is universal: "the pins in the ground govern" so find the pins (monuments) and get as good of a GPS location on them as possible ... your GPS will have an averaging capability, use it. (There's another way that I use that saves a lot of time but I won't explain that here). You want the line as accurate as possible as you will be varying a couple yards from that remember. Stand on one of the monuments and navigate to the other. There is a function in the GPS that allows you to set on the map screen that will show you how far off of that straight line "cross track error" I believe that this function has different names in different vintages of GPS ... this also allows you to weave your trail around in the bush and check proximity to that line once in a while. If you are a computer guy: Another way to draw the line is to create waypoints at the monuments and put them into MapSource or BaseCamp (Garmin software) and transfer the line to your GPS.

So ... too much information?

• A realestate agent I work for quite often that deals primarily with rural acreage has one of those apps. It usually will get you close enough where you can see a corner if it is visible. I once used a loran to navigate my boat. I now have a commercial grade gps but it isn't any better than loran. It is much more user friendly. None of the above were intended to produce survey grade results but they generally do what they were designed to do. The trouble with a GPS signal in the woods, except maybe if you are working with RTK from a good BASE, is you can never be sure how good your results are. Even then it's very problematic. I still recall my "Horror Story" experience with the engineer that thought he (mostly me) could survey 28,000 acres of swamp & alligators with numerous out parcels in a couple weeks with a GPS. A large portion of it was only accessible in a drought. There were plenty of cotton mouth water moccasins & beavers. Never did see any wild hogs while surveying but you could hear them & they weren't very far away & you could see where the big boars had debarked the base of trees with their tusks. Did see a few along side of the road while driving.

• Land Surveyor

Everyone has the classic horror story.  I had one manager that decided we could do boundary, trees and topo, on a wooded parcel at the rate of 15 acres a day.  I told him I could get all 60 acres done before lunch tomorrow.

• I hope you are just using that to get in the general vicinity to search for monuments. You can do that with about any hand held GPS, or a compass & tape. I think I'm going to get ill if I hear "app" one more time. Technology is great but today's generation can't pour a cup of coffee without a app stuck somewhere the sun doesn't shine.

That reminds me of the two old farts sitting on a park bench. One says to the other, "Sir, did you know you have a suppository in your ear?" The reply was, "Never mind that, where did I put my hearing aid?"

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