I had a quick question for you guys or ladies. Has anyone ever used google earth or some other program to determine property lines? Such as if a fence ( existing) or a structure is lying within or outside of the boundaries. Would google earth pro (costs money) perform this function? .O.
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
Learn more about the benefits and compliance details for the DOE's new water heater energy-efficiency standards.
Featured Video
Video: Build a Fireplace, Brick by BrickHighlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
I certainly wouldn't trust it. Even our tax assessor site has the property lines drawn wrong on their aerials.
Not that precise. Neither are hand held type GPS units.
When I looked at a property several years ago, the official survey was a crooked set of line segments. When plotted over an aerial photo it was evident the surveyor was trying to follow the center line of a winding blacktop access road. Heard last year the property on one side of the road was sold so a new survey was done and the original one was way off from the center of the road. it ended in a major law suite.
Google had some property (on the beach in belize) situated 1/4 mile inland
In the future that'll be beachfront property and they'll be right.
definitely not google.
Our local AHJ has stuff on gps that I can have printed out for me, but it has errors too. All of these are based on what was input at some point and where that came from.
I was checking out Mom's place in Florida on some of these internet mapping places, and the property lines show up as a wide overlay about 12-16" wide, so that makes it apparent that accuracy was not intended. one the bank down there rec to me was zillow.com
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
Zillow usually just uses the public records site (the property appraiser here) and as I said above, their aerials are about 4-6 feet off in our neighborhood. The east west grid is the worst. They have property lines cutting through structures on the picture.
Look at the Royal Observatory in Greenwich on Google, 51.477 North and 0.000 longitude. You'll find that the zero longitude line runs over a hundred feet East of the building where they have the green laser light marking the official zero at night.
Remember that this latitude and longitude stuff was all originally intended for ships at sea to find things like, say, Hawaii. Give or take a hundred feet, then look out in front of you, and that's plenty good enough for what they needed. In the sextant and chronometer days, they got by with a lot less accuracy than that.
-- J.S.
In the sextant and chronometer days, they got by with a lot less accuracy than that.
Well, true, in the terms of practical versus precise navigation. Like the instructions for sailing from LA to Hawaii: "Sail south until butter melts; then turn right and sail due west until wahini spotted."
However, the chronometer conquered the seas. Even if you required a table of offsets on the chronometer, you still measured to precise seconds (as in ±0.5 seconds) the same way you read the angular measurements off the sextant to the second of arc.
Newton was also key as he gave us the calculus needed for the three-dimensional geometry involved. Otherwise, you'd have to constantly correct for great circle courses. That terminology comes from the fact that a straight line along a sphere is an arc on a "flat" chart.
You have to check on your position every day, and preferably more than once a day, as the currents, the wind, the maritime environment are all acting upon your vessel, even as you track along a given course.
If you have the math down, you can adapt for the precision of the rest of your measuring tools. For whatever failings William Bligh had, navigation was not one of them. He used a small boat sextant and his knowledge of the seas to navigate a 21-22' boat something about 1100-1200 nautical miles. Sail a hundred miles with only 1/4 mile accuracy, and you have a 25 mile potential error, which makes it all too easy to miss a 1 mile island (you'll only have a 6-7 mile horizon in a small boat).Occupational hazard of my occupation not being around (sorry Bubba)
I use google earth, overlayed with the town tax map, and sometimes the class D survey on the deed, and some measurements pulled on site to get a good idea of boundaries. When it's close, though, hiring a surveyor is the only way I know to be accurate.
I use the free google earth but they key to overlaying the images is Photoshop, which is expensive.
Thanks for the tip, Mike I'll give it a shot.
your town may already have the plats on the GIS system... our town does
the system in the town hall has a better accuracy level than the ones i can download
our BI accepts the GIS for plot plansMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
Did your town get grants to help with the cost of creating your GIS database? Ours did, and I was under the assumption more or less that every muni got help from feds and was being encouraged to do this.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
The GIS cannot be counted on for accuracy. I know this from personal experience. I'm surprised your town accepts the GIS for use in determining property boundries.
>>>The GIS cannot be counted on for accuracy.You actually mean "GPS", right? (Global Positioning System)GIS usually refers to a software app, albeit one that does deal with Geography.
I believe the GIS stands for "geograhic information system". The county I bought some land in provides GIS mapping for property parcels.
Interestingly, the real estate outfit who advertised the property I purchased chose to use the GIS map which indicated a size of 11.25 acres. The actual parcel size, per county records, was 10 acres. I could see the outline on the GIS map included parts of my neighbor's property after I figured out where the real lot lines were. You can probably gather why the realtors chose to advertise the GIS calculations, heh, heh. It's hard to have high regard for the people who populate that profession, generally speaking.
NO! even properly done surveys are a best guess situaion.. In my property there are as many as 7 boundery markers for one corner.. the most accepted boundery marker for the other lakeside corner is an old Ford Axle..
Google and GPS solutions are deliberately dumbed down to prevent terrorism etc,
I can use the GPS on a boat and according to the coordinates be postioned 50 feet off my dock while I'm tied up to it. Google about the same.
The one useful thing it can do is show you a curve or some other abberation in the fenced property line not as apparent on the ground due to length or bushes etc.
Some GIS solutions at the very very high end can work accurately down to a few inches, but take a lot of work for the municipality to implement and few make the effort to do so.
Gavin Pitchford
"Sail fast - live slow" (build even slower)
I've found that google earth's measurements are off by as much as 5%. That's why I do multiple overlays with tax maps, GIS maps, FEMA maps, and anything else I can get my hands on, and usually pull some measurements on site as reference. It's still not 100% accurate but you can get pretty close.
GIS mapping is as accurate as whoever did the inputting of information.
Like anything else, if you put garbage in, you get garbage out.
But some is quite accurate.
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
I think the voyage that Shackleton and his small crew made to get help for the rest of the stranded Endurance crew was even more remarkable. I don't recall the details, but they crossed something like 1000 miles of ocean in a small boat with the one remaining working chronometer (out of the five the Endurance had originally sailed with). Hit the small island they were shooting for, when a miss would have meant death for both them and the rest waiting back on Elephant Island.
Here's a brief description of the trip: http://www.antarcticconnection.com/antarctic/shackleton/caird.shtml
It was my understanding that they (whoever "they" are) turned off the "dithering" several years ago. But the standard 3-satellite receivers simply can't calculate position more accurately than 10-20 feet, given their own precision, atmospheric interference, etc.
My understanding was that we went from +/- 70 feet to +/- 35 - but that could be wrong - or whoever they are just messes with us - 25 feet one way on monday - 25 feet the other on Tuesday. But make no mistake - THEY do exist ;-)My GPS on the boat operates showing 5-8 sats at a time - and it still can't tell me 100% where the dock is in the fog!Dim recollection that the issue was related to clocking - they stripped some of the fractions of a second off on some measurement, and then more recently are still stripping some of them off, but fewer.As for GIS = as someone earlier said its like anything else: GIGO - Garbage in - garbage out. If the phone guys say they installed the lines from pos x to pos y and it was really pos x+2 feet and pos y-2 feet, not a good plan to dig without checking!Gavin Pitchford
"Sail fast - live slow" (build even slower)
I would suggest a Professional Land Surveyor or a Professional Hydrographic Surveyor. They have all the tools, knowledge and expertise to help in these situations. Yep, they will cost a lot of money - it is worth the cost.
In 1985 I was told by the people that built the GPS system the inherent error is 7 meters.
Back then it was, but close accuracy is possible now with more expensive systems. And the military reservation is gone. Used to be that only the military could get the complete accurate readings.The longer a receiver stays in one place, the more reconciling it can do and the more accurate it is.So for instance, my surveying has a $3500 machine that remains in his office structure, immobile, about 12 miles from here. It communicates with the hand held units to keep them reconciled all the time, so the accuracy of his placements and readings is within less than a foot.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Yeah, there are several variations of having a nearby "base station" at a (at least relatively) known location, broadcasting correction values. This compensates for atmospheric variations.With such a system measurement within an inch or so is possible.
A strong nation, like a strong person, can afford to be gentle, firm, thoughtful, and restrained. It can afford to extend a helping hand to others. It's a weak nation, like a weak person, that must behave with bluster and boasting and rashness and other signs of insecurity. --Jimmy Carter
I talking about the overall accuracy of the GPS, 7 meters.
Not talking about dithering, not talking about error correction like your surveyor is using, just the basic inaccuracy of the system.
system tself is accurate to within a few inches. There are mopre and better satellites than back then
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
> It was my understanding that they (whoever "they" are) turned off the "dithering" several years ago.
"They" are the U.S. Department of Defense, IIRC, the Air Force. The "dithering" was called Selective Availability, or SA, and it was turned off some time in the last couple years of the Clinton administration. It looked kinda like the purely atmospheric error we have now, only bigger -- just a slow wandering, at most a walking pace.
Averaging over a long period of time can get you better accuracy on a fixed point.
Subtracting out corrections transmitted from a nearby stationary GPS receiver can cancel out most of the atmospheric wandering, since both are seeing the birds thru pretty much the same air. But that just gets you better accuracy on where your points are relative to each other. You also need the long term average for your fixed point to get better absolute accuracy.
-- J.S.
I use the City of Indianapolis GIS (imaps.indygov.org) to generate overlays, which are then imported into CAD to get a general layout of a site. You can scale the aerial photos, which have been somewhat orthographically corrected, in CAD and draw over the top of them. I do this for zoning all the time, but there is a disclaimer that says a final survey is required to confirm everythign, which would be the case no matter from where you took your overlay information.
I realize you may not have CAD, and this is simply a way to potentially achieve something you can use. I usually charge $350 to do final site plans for zoning, and the maps are created entirely this way, rarely do I have an actual survey from which to draw, or legal description which can be plugged into CAD as well).
It can be pretty rough, but it's better than a total guess, depending on how rural your site is and what frame of reference you have on the aerial picture. I have used google maps successfully to general some basic rural site plans for friends.
Good luck. You Municipality or State may have a GIS, you should definitely google GIS for your locale.
Thank you and everyone else in responding. Iwill look into it. we do live in a pretty rural area. I'm just a little suspicious of my fence lines and wanted to check them out. I have a few survey pins left. There are big discrepancies so without having to pay for a new survey which is pretty expensive, wanted to see if I could side step that process and kind of zero in on my particular situation without big bucks. O.
Be aware that fence lines etc that have a long term history have legal boundry implications.
This thread is an interesting discussion of the ramifications of a 6" discrepancy by two reputable surveyors. Their techniques were of a much higher order than Google, and photographs from outer space. Furthermore as was pointed out, existing fence lines and the original stakes can alter what the property really is, from it's legal description. So there is no way to side-step the process.
http://forums.taunton.com/tp-breaktime/messages/?start=Start+Reading+%3E%3E
Get a copy of your "meets and bounds," rent a metal detector, 100' chain, and go find'em yourself.
GPS accuracy depends on how many sat passes over the set-up. Can be as little as one tenth of a foot, verticle or horizontal.
But, what do I know, I've only been doing this 30+ years... ;-)