Landscape Survey

[Ian Wilson]

Actually, Eric, that’s pretty close to my take on the situation.

Let me ask you a question, though: How do you relate any object in the field to a boundary line, even if it’s “of record” without making a tie from the ground object to the boundary?

Can I use photogrammetry to locate objects relative to the boundary assuming that the apparent centerline intersections are at the record intersections? Can I just assume that the houses in a tract are 10 feet apart (5’ side yard setbacks) and drop the line there?

My opinion: even though the result is garbage, ANYTIME a boundary is related to a ground object, that’s land surveying. And, yes, the GIS maps of boundaries overlaid on aerial photos are significantly encroaching into land surveying even though I’ve found the Riverside County GIS to be as much as 140’ out of position!

OK...back to work...

[E_Page]

"Coordinated aerial images with property boundary."

That seems pretty clear that they are telling prospective clients that the service includes showing them where their boundaries are, even if only on a map.

"Complete topographic maps" - Says nothing limiting as to their intended use.


A product such as this can be sold to an unsuspecting public thinking that they are getting a great bargain for an accurate map of the topography of their property and of their boundary.

Again, no fieldwork (or site visit) necessary to violate the law.

[Gromatici]

Ian: To answer your first question I would say that there are "designers" of single family residences and landscape architects that do that all the time. They go out with a tape measure and get a dimension from fence to fence. Then they measure up the house. Then they draw in the boundary lines and show the house in relationship to boundary lines base on their measurements from the fences. This is for a remodel or minor improvement so the planners and inspectors never made them get a setback survey or topographic site map. They submit “siteâ€￾ maps this way all the time. Nobody ever says anything, and I’m not sure if they are requiring to or not because licensed architects do the same thing.

Years later I do a boundary survey and they confused why I'm showing the boundary line 1 foot over "here" when the plans show that it is 5' feet from my house! Trying to explain that the designer or architect is wrong never seems to go over well so I usually ask them if they have ever had a Licensed Land Surveyor come over and if not then those lines shown on paper are really just a best guess.

Also: you can download for free GIS Assessors parcels. Then you can buy Flood Control CAD files and put together a "basemap" and never have set foot in the field. I do it all the time for reconnaissance maps but a few County Assessor's websites now have ortho-photos with boundary lines shown for properties that people can download for free or pay $50 to get a hard copy. I had a client show up to the site with one and when I pointed out that his exhibit is based purely on an assessor’s tax map his wife chimed in "How can the Assessor be wrong?". It was a little frustrating to say the least. Fortunately the husband was less emotionally involved in the purchase and I could reason with him. I even know Survey companies that have done this for "planning" purposes just to get the client something for less than their competitors.

Now that we agree regarding GIS and boundaries, what are we going to do about it? Seems like we need to start meeting with these people and clearly educating them about the "boundaries" they should stay within. The public is always going to perceive any map as being accurate. They simply are ignorant when it comes to these things. Most of the time it's harmless, such as a hiking map or winery tour map. But when it comes to property lines, you’re going to have problems.

Evan: Getting spanked is the only way I was able to learn! I do agree with you on this company, but until we know the details of who their officers are, I was trying not to be too harsh. It does beg the question though. I wouldn't say that what I was giving them was a "topo" with property lines. I think it is simply misleading. They can't use it, even for planning purposed here in Santa Barbara.

[Gromatici]

If you start reading the site you'll see that they make LS's sound like overpaid idiot's. They say things like "poor bearing derived datum (miles away!)." Then they say that Surveyor only give you contour intervals that might only be acurate 20% of the time and they will give you 0.5' contours. That sounds like the company doesn't really understand the concept of "accuracy" at all. I can take 4 shots and give you 1" contours, but that doesn't make it accurate (or precise!) It seems to have the flavor of someone who does not really know what mapping and surveying is even though they say they have "licensed surveyors".

They even have an example where someone paid $53,000 to a photogrametrist (I doubt that- probably the LS) and they did it for $1000.00. It's definitely worth investigating.

I've used LIDAR before, and it good for hydrology studies and that's about it unless you order the flight yourself and compile the data yourself. It's alot more than $1000 too!

http://www.nvdmapping.com/nvdm_cs01.htm

If you look at the sample, you can see that their contours are grossly inaccurate.

[E_Page]

The BPELS LS Consultant (Ric) is already on it. See his post from last night.


That NVD doesn't understand Precision vs Accuracy is apparent by their discussion of it on their site. They start out by telling the reader that there is a difference, and then go into a discussion that seems to say that their product is more accurate because it's more precise.

I'd venture to say that they are precisely wrong.

[Ric7308]

Evan, that may be an accurate statement