Using GPS to lay out a field

[quicksandfarmer]

I have a good idea where my corners are. My 20 acre, nearly square parcel is bounded on two sides by two intersecting roads, so the exact corner there is unimportant... the practical boundaries on those two sides are the two roads. One boundary is a state wildlife area, and it's roughly marked with paint on a line of trees. The two corners that interest me have been surveyed. One is supposed to have a pin, but I was unable to find it. The other is a "stone", and sure enough, there's a painted stone along the property line I share with the state, right where my GPS said it should be, within the error of the GPS.
There's a property marker across the road from the corner with the missing pin, but it's not got a surveyor's cap on it, it's a painted "T" post, but I believe it's pretty close based on my GPS and measuring from corner at the intersection of the roads.
I think, but am not certain, that my boundaries are recorded with lat and long coordinates. I'll have to dig out the document to be sure. Three of the corners are on roads, so I have a pretty good view straight up, but there are trees on both sides. That fourth (the painted stone) corner is in the woods, but my handheld GPS has reception there.
Thank you all for the input! It's much appreciated. I may just buy that kit to have it, I'm a ham radio operator, fly model airplanes, and bought a hand-held GPS WAY back when they first became generally available and were WAY too expensive. In other words, I like my gadgets.

If you have latitude and longitude PM me and I will draw a 1-yard circle on the aerial photo from Google Maps at that exact spot and send it to you. If there are landmarks on the ground the aerial photo can get you very close to the exact spot.

 

[dodge man]

It would be really rare to have a lat and long on a boundary survey but maybe it could be a regional thing.

 

[s219]

It would be really rare to have a lat and long on a boundary survey but maybe it could be a regional thing.

I have never seen it here, but a lot of property owners get really confused thinking their property line bearings (in deg-min-sec) are a position coordinate. Can't tell you how many times someone has asked me for help with that .

 

[quicksandfarmer]

So it turns out the precision is closer to 2 cm than 1 cm. The DGPS unit is capable of 1 cm precision, but its output is in NMEA format. The NMEA format has latitude and longitude in degrees and minutes, the minutes are reported with five decimal places. So the minimum precision is 0.00001 minutes. At my location one minute of latitude is about 1800 meters and one minute of longitude is about 1450 meters. So 0.00001 minutes is about 1.8 cm of latitude and 1.45 cm of longitude. For my application so far that's fine. U-blox does have a proprietary format that gives greater precision if needed.

 

[dodge man]

As a rule surveyors do not work in latitude and longitudes although it is a mathematical conversion to state plane coordinates from lat and long.

One thing, speaking as a surveyor, that would limit the use of your system is the interface. We use data collectors that give a lot of information. QA/QC numbers being important. When using ours one thing I keep an eye on the display is if the solution is fixed, float or autonomous. Fixed means cm level accuracy, float means something is wrong, such as to many trees, and autonomous means your radio link is down.

A couple of things, GPS does not work in tree cover. There have been huge improvements in how it works in the trees but once the leaves are out, you just can not get a fixed solution.

Also the precision of GPS is not that great. If you take a single measurement on a point, shoot it the next day, it won稚 check that great. I am talking an error of a half inch or more sometimes. What this means is for critical measurements such as bridges, building layout and paving operations, it is not good enough. Say you use GPS to shoot property corners 20 feet apart, you would get a better measurement with a 30 foot carpenters tape measure. Where it shines is longer distances, places you do not have line of sight, and where precise measurements are not critical.

Another point is GPS does nothing to improve boundary surveying. It makes it easier, it is another tool but the answer is not floating around in space in satellites. There is a list of calls in order of importance, such as call to adjoined, natural monument, man made monument, bearing, distance, area and coordinates. Coordinates is last on the list meaning you give it the least weight. That is because you do not always know how the surveyor got the coordinates. What did he start from, what equipment did he use? To many variables now to move it to the top of the list.

 

[pmsmechanic]

Question here. So do you need a pin finder to find pins or will a metal detector or similar work? I'd like to find the pins on my property without spending a lot of money. I know where they are within a few feet but I would like to know exactly.

 

[BrokenTrack]

Question here. So do you need a pin finder to find pins or will a metal detector or similar work? I'd like to find the pins on my property without spending a lot of money. I know where they are within a few feet but I would like to know exactly.

I use a metal detector. It does more than just find the pins. A lot of times it might pick up on old barb wire, page wire fencing, or hardware from an old fence long since rotted. All these may indicate where the property line is.

Another indicator here is big trees. Many times the biggest trees are on the property line because neither landowner dared to cut the trees down. Along the same lines, a change in tree species, can also be an indicator. The way it works here is: on new growth, softwood comes up first, then after 80 years or so, it starts switching to hardwood. So if you are near the line, and suddenly there is a change from pure hardwood, to softwood, you can bet that is where the line is. I would never lay out a property line using that alone, but it will let me narrow in on where to take my metal detector and start looking for barb wire, page wire fencing, and line pins.

Here in Maine, only surveyors can set a pin, but anyone can re-do what has already been laid out for a line. What I am finding lately though is, most landowners have no clue where the property lines are. A few weeks ago I had a neighbor sell my land on me, but granted it is very remote here.

 

[dodge man]

A metal detector will work. The ones we use tend to only find iron, not coins and other stuff the treasure hunters look for. I probably dig up 3 pieces of junk for every corner I find.

 

[quicksandfarmer]

As a rule surveyors do not work in latitude and longitudes although it is a mathematical conversion to state plane coordinates from lat and long.

One thing, speaking as a surveyor, that would limit the use of your system is the interface. We use data collectors that give a lot of information. QA/QC numbers being important. When using ours one thing I keep an eye on the display is if the solution is fixed, float or autonomous. Fixed means cm level accuracy, float means something is wrong, such as to many trees, and autonomous means your radio link is down.

A couple of things, GPS does not work in tree cover. There have been huge improvements in how it works in the trees but once the leaves are out, you just can not get a fixed solution.

Also the precision of GPS is not that great. If you take a single measurement on a point, shoot it the next day, it won稚 check that great. I am talking an error of a half inch or more sometimes. What this means is for critical measurements such as bridges, building layout and paving operations, it is not good enough. Say you use GPS to shoot property corners 20 feet apart, you would get a better measurement with a 30 foot carpenters tape measure. Where it shines is longer distances, places you do not have line of sight, and where precise measurements are not critical.

Another point is GPS does nothing to improve boundary surveying. It makes it easier, it is another tool but the answer is not floating around in space in satellites. There is a list of calls in order of importance, such as call to adjoined, natural monument, man made monument, bearing, distance, area and coordinates. Coordinates is last on the list meaning you give it the least weight. That is because you do not always know how the surveyor got the coordinates. What did he start from, what equipment did he use? To many variables now to move it to the top of the list.

Thanks Dave. I wouldn't dream of using this for boundary surveying or anything where anything real is at stake. That said, I have a 300' tape measure that I use all the time, the idea of being able to draw a line on a map on my computer and then being able to go out and walk that line just seems like it could replace a lot of the things I use that 300' tape for. I could see using it for fencing, planting trees, plowing rows, etc. I doubt I'm getting 1" accuracy with the tape anyway. I built a 96' greenhouse with 25 hoops and I would have loved to get 1" accuracy placing those hoops.

What got me started on this thread was an earlier thread about using laser sensors to set the height of a box blade. There's a lot of possibilities for automated control once you can determine your location relatively accurately. I haven't even thought about what you could do behind the wheel of a tractor. The ultimate project would be some sort of autonomous vehicle, maybe something that mows the fields while I do something else. But that's advanced stuff.

The U-Blox unit will tell me if the solution is fixed, float or autonomous. (I had forgotten the terminology in an earlier post). I change my display base on what it tells me. If I'm getting fixed the current location is marked with the small blue X:

If I'm getting a float solution I mark it with a larger, yellow X:

The idea is the size of the X roughly represents the accuracy. If I'm getting autonomous it's a much bigger red X.

Agree that you can't always get a fix, I spend a lot of time at some sites trying to get that blue X. You need line of sight to the satellites. Generally fields work pretty well.

I appreciate your comments, it is very helpful to hear from someone who knows a lot more than I do about the real-world use of this technology.

 

[BrokenTrack]

I have noticed over the last 40 years that the USDA has improved their accuracy. For years they said we only had so many acres, which was 20 acres less of farm land that we always said we had. But I always assumed it was because they go by a flat area, where as we live in very rolling hills. It would be like taking an 8x 11 sheet of paper, and tracing around it. Then taking that paper and twisting it and looping it...then tracing around it. The same square area would fit into a much smaller space. But now I noticed, their acreage amounts have increased to where it matches what we always said it did, I assume because with GPS they can take into account land contour better.

It has gotten to the point of accuracy now, that with GPS and LIDAR, I can go on the USDA website, Web Soil Survey, and map out my fences. I can take the footage and calculate my wire, my fence posts needed, and everything, and know I will only be off by a few feet in actual construction. That is pretty neat since I can do all this on a rainy day, and never step outside.

It is the same with soil types. My soil samples physically gathered, and sent in, always have matched what Web Soil Survey says it is.

 

[dodge man]

Machine control is pretty amazing, it’s also very expensive. Top of the line it controls the hydraulics of the machine. It’s common on dozers, motor graders skid steers and pavers. For paving you can even mix GPS in with a rotary laser and robotic total stations.

A good very simple example is cutting a new ditch. We survey it ahead of time and set some control points. We design the ditch in the office. The contractor takes the design and builds a 3D model. The is loaded in the machine, say a D6 bulldozer. They use our control point to calibrate their GPS to the site. The operator has a display and he follows the alignment and the machine tilts the blade and controls how deep it cuts. The operator often just uses the display as a guide to start. Say the starting cut is 30 feet. The dozer would drop the blade and try and cut 30 feet. Not going to happen so once the grade is close the machine takes over.

 

[Complete Turf Care]

I work a lot with sports turf facilities. About 2 years ago, I met a guy who was from the Netherlands at the Sports Turf Managers Association conference. He had a robotic painter that would paint sports fields. He would enter a template on a Google Earth map, and the robot would automatically paint the field.

I wanted to become a dealer for his products here in the USA, but his company decided not to market their product here. I don't recall the name of his company.

However there is another company here in the USA that does market such a robot. Here is a link. Turf Tank - Intelligent GPS paint robot for all sports

I do some work with Baton Rouge Recreation (BREC) and they have used one of the Turf Tank robots. One of their facilities has 20 or more soccer fields that need to be painted on a regular schedule and this seems to help save labor and makes it more accurate.

It seems that your system could be adapted to do something similar. I think there is a huge market for such robots, and if you could build one for a reasonable price, I would be very interested in purchasing such a system.

Here is a good video of the Turf Tank in action. I work with the guys in the video on many projects. BREC and Turf Tank CBS News Story - YouTube

 

[npalen]

I'll bet that R2 and D2 could stripe a parking lot if given the opportunity.

 

[npalen]

Machine control is pretty amazing, it痴 also very expensive. Top of the line it controls the hydraulics of the machine. It痴 common on dozers, motor graders skid steers and pavers. For paving you can even mix GPS in with a rotary laser and robotic total stations.

A good very simple example is cutting a new ditch. We survey it ahead of time and set some control points. We design the ditch in the office. The contractor takes the design and builds a 3D model. The is loaded in the machine, say a D6 bulldozer. They use our control point to calibrate their GPS to the site. The operator has a display and he follows the alignment and the machine tilts the blade and controls how deep it cuts. The operator often just uses the display as a guide to start. Say the starting cut is 30 feet. The dozer would drop the blade and try and cut 30 feet. Not going to happen so once the grade is close the machine takes over.

The parallel between this mobile machine control and CNC machining in the shop is interesting. The CAD and CNC 3D world has so many similarities to GPS and earthmoving.

 

[quicksandfarmer]

I work a lot with sports turf facilities. About 2 years ago, I met a guy who was from the Netherlands at the Sports Turf Managers Association conference. He had a robotic painter that would paint sports fields. He would enter a template on a Google Earth map, and the robot would automatically paint the field.

I wanted to become a dealer for his products here in the USA, but his company decided not to market their product here. I don't recall the name of his company.

However there is another company here in the USA that does market such a robot. Here is a link. Turf Tank - Intelligent GPS paint robot for all sports

I do some work with Baton Rouge Recreation (BREC) and they have used one of the Turf Tank robots. One of their facilities has 20 or more soccer fields that need to be painted on a regular schedule and this seems to help save labor and makes it more accurate.

It seems that your system could be adapted to do something similar. I think there is a huge market for such robots, and if you could build one for a reasonable price, I would be very interested in purchasing such a system.

Here is a good video of the Turf Tank in action. I work with the guys in the video on many projects. BREC and Turf Tank CBS News Story - YouTube

Well that's interesting! They beat me too it. Of course that system is $35,000. I do think this is the future, once you have the DGPS box to tell you your location to the centimeter it's pretty straightforward to have a wheeled vehicle follow a path. I expect this is just the tip of the iceberg. For example, I'd imagine the owner of those fields spends more money to have them mowed than to have them lined. It wouldn't be outrageous to spend $35K for a mower that could mow all day with no human. Of course you'd need robust obstacle detection and collision avoidance to keep from killing people.

I imagine as the technology improves the price will come down and we'll be seeing it in consumer products in a few years.

 

[npalen]

There are many farmers out there that could make use of sub inch precision for row crops but the cost is prohibitive for other than big time operators.

 

[Complete Turf Care]

Well that's interesting! They beat me too it. Of course that system is $35,000. I do think this is the future, once you have the DGPS box to tell you your location to the centimeter it's pretty straightforward to have a wheeled vehicle follow a path. I expect this is just the tip of the iceberg. For example, I'd imagine the owner of those fields spends more money to have them mowed than to have them lined. It wouldn't be outrageous to spend $35K for a mower that could mow all day with no human. Of course you'd need robust obstacle detection and collision avoidance to keep from killing people.

I imagine as the technology improves the price will come down and we'll be seeing it in consumer products in a few years.

So? You've got about what? $1500? $2000? invested in your system? Why not invest another $2000 and put it into a battery powered painter, and sell it for $25,000 and be $10,000 cheaper than the competitor, and save the turf managers tons of money on time and labor?

I'm in....

 

[quicksandfarmer]

So? You've got about what? $1500? $2000? invested in your system? Why not invest another $2000 and put it into a battery powered painter, and sell it for $25,000 and be $10,000 cheaper than the competitor, and save the turf managers tons of money on time and labor?

I'm in....

Once you turn it into a business it stops being fun to tinker.

I used to work in technology. You've hit on why it's a dog-eat-dog business -- prices are always falling. Which means the new guy coming in always has the price advantage, he can enter at a lower price point. Plus you have to worry about Silicon Valley startup convincing a venture capital fund to give them $100 million so they can give the product away for free to "develop the market." And you have to worry about some guy in China ripping off your design and selling it for cents on the dollar.

If the DGPS chips are $80 each right now they'll be 80 cents before you know it. The guy selling the $35,000 paint sprayer is in for a rough ride.

 

[Complete Turf Care]

Once you turn it into a business it stops being fun to tinker.

I used to work in technology. You've hit on why it's a dog-eat-dog business -- prices are always falling. Which means the new guy coming in always has the price advantage, he can enter at a lower price point. Plus you have to worry about Silicon Valley startup convincing a venture capital fund to give them $100 million so they can give the product away for free to "develop the market." And you have to worry about some guy in China ripping off your design and selling it for cents on the dollar.

If the DGPS chips are $80 each right now they'll be 80 cents before you know it. The guy selling the $35,000 paint sprayer is in for a rough ride.

You are probably right. Technology changes so fast. Enjoy your tinkering....

 

[BrokenTrack]

Machine control is pretty amazing, it痴 also very expensive. Top of the line it controls the hydraulics of the machine. It痴 common on dozers, motor graders skid steers and pavers. For paving you can even mix GPS in with a rotary laser and robotic total stations.

A good very simple example is cutting a new ditch. We survey it ahead of time and set some control points. We design the ditch in the office. The contractor takes the design and builds a 3D model. The is loaded in the machine, say a D6 bulldozer. They use our control point to calibrate their GPS to the site. The operator has a display and he follows the alignment and the machine tilts the blade and controls how deep it cuts. The operator often just uses the display as a guide to start. Say the starting cut is 30 feet. The dozer would drop the blade and try and cut 30 feet. Not going to happen so once the grade is close the machine takes over.

To me this is a silly use of the system.

GPS and whatnot has its place, but more for planning, like a contractor calculating what the overburden removal amount would be. Even that is a bad example because it is going to be what it is going to be, no more, and no less.

Using GPS and what not to establish where a ditch already is, like using GPS to find your way back home from the grocery store...you already know where it is, so why go high-tech?

As a sheep farmer I have run into this line of thinking when a Vet suggested I do Ultrasounding of my sheep so I could determine which ewes had singles, twins and triplets. The idea was, knowing beforehand, I could feed them accordingly to get a better survival rate.

It sounds good but...

Why not just feed ALL the ewes as if they were having twins, and save the cost of NOT having to Ultrasound? The extra cost of feed for ewes with singles is pretty darn low anyway, and what few triplet lambs I would lose, would be a lot less then the cost of ultrasounding. It just did not make sense because despite the cool factor of modern technology, it was not changing the outcome. The ram did his thing, and I was getting for lambs, what I was getting for lambs. High tech was not changing anything.

And it is the same thing with a ditch of a road. Why use technology to tell me what I already know..."jeesh look, there's the darned ditch." If it looks like a ditch, sheds water like a ditch, and is located on the edge of the road...it is probably a ditch...no technology needed for that.