I HATE GIS!
Trying to explain to a client that property lines on these maps are not correct is the pits. If they get the map online, from a government agency, then by GOD, it is gospel.
RANT off!
joe
> I HATE GIS!
>
> Trying to explain to a client that property lines on these maps are not correct is the pits. If they get the map online, from a government agency, then by GOD, it is gospel.
>
> RANT off!
>
> joe
I feel your pain man. But, maybe you should look at this as an opportunity to help your client (prospective client?) better understand surveying and the limits of GIS.
Those people that do not want to understand or that do not trust you to know your profession and tell them the truth need to be someone else's headache.
Something to consider.
Larry P
Larry,
My client liked the fact that the GIS is wrong. It is the neighbor that insists it is right.
Nothing I say will change their mind. Even though he said he built the fence where the old one was(+/- 5' from the deed line, not bad for this area), the GIS shows the line to be about 80' east and he wants it.
joe
Generally speaking, GIS screwups like that have brought me a ton of business over the past 20 years. Initially, a lot of the problem was that everything was printed on large mylar sheets. Aerial view on one sheet. Topography/soil types on a second. Idealized property boundaries on a third. They would lay them atop one another on a light table to help visualize what was what. Sometimes the sheets would slip a bit relative to each other producing the "his garage is on my lot" scenario fairly often.
Seems as though this kind of friction has tapered off the last year or two. Maybe I'm just lucky.
I matter-of-factly told the last "adjoining" neighbor that was vocally adamant about the precision of the County's GIS crap to contact the county and see how much it costs to get a "certified" copy of their GIS map that guaranteed their accuracy.
In a nutshell, I won't argue with folks that won't listen. Be pleasant and professional and 100% apathetic to their noise. You will live longer. B-)
I LOVE GIS!!!
> My client liked the fact that the GIS is wrong. It is the neighbor that insists it is right.
>
> Nothing I say will change their mind. Even though he said he built the fence where the old one was(+/- 5' from the deed line, not bad for this area), the GIS shows the line to be about 80' east and he wants it.
And you just explained one of the reasons us surveyors should love it. Aside from an awesome data base resource tool, it is also a good source of work when dealing with these situations.
Sometimes with stubborn clients (or adjoiners) I will direct them to the county GIS department for verification that the GIS is OFTEN wrong. I've even given adjoiners others surveyors phone numbers.
No matter what, you do have to take those 20 minutes to explain things in terms they can understand.
The county I live in has a disclaimer on their website, as I'm sure most do. It seems that telling them about the disclaimer helps, or better yet, showing it to them.
The south part of mother's property (sister and I now) runs across the road (imagine a square with the northwest quarter removed and a road north/south along the center). According to the county GIS, my sister and I own the house across the road. Don't worry, there is a house on the neighbors property, it's the next one down. Those people are the ones without a house.
I use this example every time someone brings me one of those aerial photographs with the tax parcel lines on it. That's usually enough to convince them the maps are worthless.
> The county I live in has a disclaimer on their website, as I'm sure most do. It seems that telling them about the disclaimer helps, or better yet, showing it to them.
Disclaimer? Come on man. Who reads the disclaimer?
Nobody that I know. 😉
The GIS where I work is very good. But even they are far from perfect. When clients want to complain about how bad it is and how many mistakes the database contains I just tell them that you can't give the Tax Mapper a bunch of sows ears and expect her to produce silk purses.
Larry P
@HolyCow, with mylar sheets it sounds like you're describing pre-digital GIS? Much more than 20 years ago?
The ones in my home county were made about 1987ish. They were all there was until about mid-90's as it took a looooong time to agree on what software and such before they ever began recreating them in the computer. They still have two people working every day to make updates and add items that have been left off. With fewer than 18,000 total population in the county, the GIS office doesn't get near the funding they could really use.
c'mon guys...
..we all HATE how some folks accept the pretty pictures on the 'net as gospel, I'll agree.
But I've got to say I use the hell outa the County's on-line info. In a matter of seconds with a clickety-click I can download all the adjoiner's latest conveyance by Book & Page...recorded plats..and surveys (in some counties).
I use to keep rolls of quarters in my truck for the parking meters at the Courthouse. I don't even know the ladies' names at the Registrar of Deeds Office anymore. A few of the larger local municipalities have water-sewer-paving project numbers on their GIS layers making retrieval of as-built info a quicky.
I can remember when putting together all the available info for a project took gasoline and a couple of days. Today I listened to the Allman Brothers while I collected everything with my backside glued to a comfy overstuffed chair...
Slicker'n cat-crap on linoleum. Yes-indeedy-doo.
I usually find most people ready willing and able to grasp the fact that 'The Government has done a piss poor job' (clients words, not mine) and the lines on GIS are often in an incorrect position.
We're upgrading the Cadastre in our city at the moment though and have already done 4 stages bringing the accuracy of the GIS down to better than 0.1m.
Still sections of the city that are up to 20m out though...
> I HATE GIS!
>
> Trying to explain to a client that property lines on these maps are not correct is the pits. If they get the map online, from a government agency, then by GOD, it is gospel.
>
> RANT off!
>
> joe
I find it helpful to keep I mind that there is a common division between GPS accuracies: survey grade, mapping grade, and recreational grade. More and more I find myself applying this division to geospatial data in general, and that is what is going on with the property boundary layers in most municipal gov't GISs.
Not always, but usually, the property lines originate from the old paper tax maps being scanned in and digitized. Obviously, the resulting lines can only be less accurate than the old paper maps and how accurate were they?
Not always, but usually, the building layer is digitized from aerial imagery that hopefully was ortho-rectified, and hopefully the rooflines were corrected to foundation positions. If the bldg. corners are obscured by trees or other buildings, then the tech will guesstimate the true location. Often a building corner is indistinguishable from it’s shadow.
So, does combining two vast sources of data, each with its own inherent errors result in a flawless product? Boy howdy, it sure don’t.
Yet, the GIS property line layer is extremely useful to many people, professional and otherwise. Just not so much to land surveyors, at least not for property boundary resolution.
The problems only emerge when someone expects survey grade accuracy from a mapping grade product. As professionals, we should be able to articulate to the rest of the world what the differences are and explain how they came about.
Stephen
I Saw Some Great Mylar Overlays
Just over 20 years ago. Lehigh and Berks Counties, PA did aerial orthophoto updates. You could buy the tax sheet and accompaning ortho photo and the overlay was fantastic including SPC grid lines.
Some other area counties also did, but I was not doing work in them that would require that data.
Paul in PA
As long as it's used properly as a catalog device it's great, but GIS has done real people real harm because of it's misuse.
I've been involved with one property owner that went to court and sued the "GIS" or the city which improperly used the GIS to harm the property owner. The court basically laughed at the city/county and their disclaimer. They completely threw out that argument and because the mistake on the GIS helped the property owner and correcting the mistake would harm the property owner the court said the city was liable for that mistake and would have to live with or pay for it.
But that case is just the tip of the iceberg, many people are harmed by the incompetence of GIS technicians.
> As long as it's used properly as a catalog device it's great, but GIS has done real people real harm because of it's misuse.
>
Are we to blame the tool if someone misuses it?
Even if the creator of the tool very specifically tells everyone that the tool is not intended to be used for purposes other than originally designed?
Not wanting to turn this into a political discussion; but, that sounds like the same logic that will be used to sue Remington because someone used a 16 gage shotgun to kill someone.
>
> But that case is just the tip of the iceberg, many people are harmed by the incompetence of GIS technicians.
All the more reason to license and regulate.
Larry P
All the more reason to license and regulate.
They already are licensed and regulated. In the cases I've seen, GIS techs preformed engineering and surveying by placing information that only engineers and surveyors are allowed to do into their maps.
This information is incorrect and it caused actual property owners harm.
This is a computer program, the information that is placed in it can be done correctly. If the county or city wants to place a flood plain on their map over property lines then the county or city surveyor and engineer better review and sign off on the accuracy of that flood plain and the property lines that are affected by them. If they can't do that then don't place that information on the maps. I can't get away with sending out maps to the public that are grossly incorrect and then say I have a disclaimer. It's why we hire professionals to work at these government jobs to review and sign off on the work that's being done.
No computer programmer will ever be able to do that job so why bother regulating them for it?
:good:
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> This information is incorrect and it caused actual property owners harm.
>
It's not incorrect. Incorrect means inaccurate. The information is accurate to its standards which is mapping grade standards. It is not accurate to survey grade standards, but that is OK, because it's not a survey.
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> This is a computer program, the information that is placed in it can be done correctly. If the county or city wants to place a flood plain on their map over property lines then the county or city surveyor and engineer better review and sign off on the accuracy of that flood plain and the property lines that are affected by them. If they can't do that then don't place that information on the maps.
Actually it cannot be done, at least in practical terms. That would a boundary survey on every property within the municipality. There is not enough money to pay for that and there aren't enough surveyors to perform it.
>
> This is a computer program, the information that is placed in it can be done correctly. If the county or city wants to place a flood plain on their map over property lines then the county or city surveyor and engineer better review and sign off on the accuracy of that flood plain and the property lines that are affected by them.
>
Actually it cannot be done, at least in practical terms. That would require a boundary survey on every property within the municipality. There is not enough money to pay for that and there aren't enough surveyors to perform it.
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>
> If they can't do that then don't place that information on the maps. I can't get away with sending out maps to the public that are grossly incorrect and then say I have a disclaimer. It's why we hire professionals to work at these government jobs to review and sign off on the work that's being done.
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Sure you can. You can make a map just like anyone else. You just can't make a property survey and disclaim your liability away. By your logic, Rand McNalley was wrong to draw maps with state, county, or city limit lines. USGS was wrong to make 7.5' topo quads with section lines shown. And all of the old paper tax maps... well that's just flagrantly illegal, right?
Stephen
