Mike Lacey, post: 375380, member: 303 wrote: What's your go to tool, GPS or Total Station/Robot, and why? Assume you are doing a 5 acre survey that is fairly open and rolling. If you were using your total station, you can do it with four set ups, and if you were using your GPS, you can shoot/set all the corners.
Well, I'd say that the best results will involve both. The GPS gear is an easy way to orient the survey to grid North of the State Plane Coordinate System and connect to NAD83, but a good total station should give superior accuracy for less effort in the connections between stations. The other element to a typical survey is that often one or more of the boundary markers is found to have been disturbed or is missing. In that situation, the total station takes the worry out of being close.
The other consideration is whether the survey is to meet any particular accuracy specification or not. If the survey is to meet ALTA/NSPS standards then chances are that the GPS alone won't get you there efficiently, particularly if it is just quickie-dickie RTK.
The ALTA/NSPS spec states:
"The maximum allowable Relative Positional Precision for an ALTA/NSPS Land Title Survey is 2 cm (0.07 feet) plus 50 parts per million (based on the direct distance between the two corners being tested)."
That means that the semi-major axis of the 95%-confidence relative error ellipse between two points can't exceed 0.07 ft. + (50ppm x D). In the case of a small tract like 5 acres in a square, the distances would be about 467 ft. between adjacent sides and 660 ft. on the diagonal.
467 ft. x 0.000050 = 0.02 ft. and
660 ft. x 0.000050 = 0.03 ft.
So, the maximum allowable values of the relative error ellipses between points positioned by the survey would be 0.09 ft. between adjacent corners and 0.10 ft. along diagonals. To meet that spec an uncertainty on the order of +/-0.03 ft. (68% confidence) in the N and E components of the coordinates would be at the threshold of failure. For quickie-dickie RTK, demonstrating that the survey actually meets that spec would also seem to be a natural problem that would not be present using a total station with well-characterized uncertainties in its angle and distance measurements.
Kent McMillan, post: 375568, member: 3 wrote: The other consideration is whether the survey is to meet any particular accuracy specification or not. If the survey is to meet ALTA/NSPS standards then chances are that the GPS alone won't get you there efficiently, particularly if it is just quickie-dickie RTK.
The ALTA/NSPS spec states:
"The maximum allowable Relative Positional Precision for an ALTA/NSPS Land Title Survey is 2 cm (0.07 feet) plus 50 parts per million (based on the direct distance between the two corners being tested)."
That means that the semi-major axis of the 95%-confidence relative error ellipse between two points can't exceed 0.07 ft. + (50ppm x D). In the case of a small tract like 5 acres in a square, the distances would be about 467 ft. between adjacent sides and 660 ft. on the diagonal.
467 ft. x 0.000050 = 0.02 ft. and
660 ft. x 0.000050 = 0.03 ft.So, the maximum allowable values of the relative error ellipses between points positioned by the survey would be 0.09 ft. between adjacent corners and 0.10 ft. along diagonals. To meet that spec an uncertainty on the order of +/-0.03 ft. (68% confidence) in the N and E components of the coordinates would be at the threshold of failure.For quickie-dickie RTK, demonstrating that the survey actually meets that spec would also seem to be a natural problem that would not be present using a total station with well-characterized uncertainties.
So what?
A "quickie-dickie" survey with a Total Station (or a T-3 & INVAR TAPE) could fail too!
Now I agree that RTK is not the best choice for something that size, but it could be done!
Loyal
Loyal, post: 375569, member: 228 wrote: So what?
A "quickie-dickie" survey with a Total Station (or a T-3 & INVAR TAPE) could fail too!
Now I agree that RTK is not the best choice for something that size, but it could be done!
The point is that you have to really work hard to mess up a distance and angle measurement with a good total station. I'm not saying that it can't be done, but instruments have improved so much that even the quickie-dickie surveyors are using total stations that can measure distances with standard errors of less than 0.01 ft. More or less ditto for angles measured with an instrument with dual-axis compensation.
But RTK? Katie, bar the door!
Kent McMillan, post: 375570, member: 3 wrote: The point is that you have to really work hard to mess up a distance and angle measurement with a good total station.
Yep, but Doofus & Goofus are experts at that sort of thing.
Doesn't really matter which hammer you give those guys, they're mash their fingers with it!
o.O
I'll start by doing everything I can with rtk, then clean up with total station. I can revisit each point twice in your example faster than I could survey it with a robot. There is no planning of traverse or traversing required.
The exception to this for me is vertical. If I need elevations better than 0.1' on several points, rtk isn't going to be efficient generally.
By the way I'm going to alwaystry to use the most efficient tool for the task at hand. The corollary to that is I charge the same rate for all of it. We'll see how that ultimately turns out, but that's my goal. Drafting, research, digging, rtk, total station... all at x per hour.
Loyal, post: 375572, member: 228 wrote: Yep, but Doofus & Goofus are experts at that sort of thing.
Doesn't really matter which hammer you give those guys, they're mash their fingers with it!
I'm thinking more about the quickie-dickie survey work that I follow in the normal course of business. The quickie-dickie RTK work is invariably more seduced than just plain old conventional work with a total station and I think that the reasons are that the conventional methods are harder to seduce.
Shawn Billings, post: 375576, member: 6521 wrote: By the way I'm going to alwaystry to use the most efficient tool for the task at hand. The corollary to that is I charge the same rate for all of it. We'll see how that ultimately turns out, but that's my goal. Drafting, research, digging, rtk, total station... all at x per hour.
Question: why have you chosen to practice under a name like "Pendulum Surveying" instead of "Shawn Billings and Associates" or something similar?
I'm not knocking "swings both ways", but the fakey corporate-sounding names mainly serve to make land surveying seem like a commodity rather than a service offered by a specific, responsible professional.
Kent McMillan, post: 375577, member: 3 wrote: I'm thinking more about the quickie-dickie survey work that I follow in the normal course of business. The quickie-dickie RTK work is invariably more seduced than just plain old conventional work with a total station and I think that the reasons are that the conventional methods are harder to seduce.
I see that I screwed up my reply above (left out "they're [going to] mash")
In any case, I agree with you in general.
Despite the relative ease in which one can use RTK (or GPS in general) to return good to excellent results, there are far too many folks out there who can't seem to pull it off. This is NOT the fault of the hammer, and it's not fair to blame the hardware store (or Stanley Tools either). There seems to be quite a few of them that can't [properly] run a Total Station either.
Murphy's Law is one of the few real constants in the Universe.
Loyal
We at Pendulum Surveying value the opinions of the public and appreciate your thoughtful suggestion. Be sure to answer our customer questionnaire for 10% off your next survey.
I guess I should have called you and asked for your opinion before I registered my firm name and dba.
Shawn Billings, post: 375581, member: 6521 wrote: We at Pendulum Surveying value the opinions of the public and appreciate your thoughtful suggestion. Be sure to answer our customer questionnaire for 10% off your next survey.
"Look for our coupon in your email for a great discount on your next survey and fabulous deals at All-Skin Tattoos and other local businesses".
In the meantime, please keep in mind that while we at Pendulum Surveys may swing both ways, that doesn't mean that Roulette Surveying, Jackpot and Associates, or Wheel-of-Fortune Mapping, can't also service your needs. (Offer void where prohibited by law.)
Kent McMillan, post: 375578, member: 3 wrote: Question: why have you chosen to practice under a name like "Pendulum Surveying" instead of "Shawn Billings and Associates" or something similar?
I suppose that "More Billings & Associates" was already taken, as were "Billings, NextGen & Associates" and "Billings Ver 2.0 & Associates".
Kent, that is rude, and UN-professional.
Nate
Nate The Surveyor, post: 375590, member: 291 wrote: Kent, that is rude, and UN-professional.
Not really. Land surveying is what a land surveyor does. The corporate-sounding operations with names like franchise businesses only serve to conceal that reality and mainly work to deceive the public into thinking they are buying a commodity instead of a professional service. In my opinion, a land surveyor should have a pretty good excuse for not practicing under his or her own name.
Nate The Surveyor, post: 375590, member: 291 wrote: Kent, that is rude, and UN-professional.
Nate
Careful Nate , he's...
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Loyal, post: 375594, member: 228 wrote: Careful Nate , he's...
Actually, I'm merely pointing out the obvious. I'll acknowledge that in the age of the internet there may be some legitimate reason to make a place describing one's area of practice part of the company name, but how many variations on East Texas and Pine Trees are there, really? I realize that there are some folks like you for whom "Have Gun Will Travel" might work just as well, but didn't even Richard Boone ultimately settle on Paladin as his business name?
Kent McMillan, post: 375593, member: 3 wrote: Not really. Land surveying is what a land surveyor does. The corporate-sounding operations with names like franchise businesses only serve to conceal that reality and mainly work to deceive the public into thinking they are buying a commodity instead of a professional service. In my opinion, a land surveyor should have a pretty good excuse for not practicing under his or her own name.
That is pretty ludicrous even for you. I need to provide you an excuse for why I named my company something other than what you thought it should be? Yeah I'll get right on that.
Shawn Billings, post: 375597, member: 6521 wrote: That is pretty ludicrous even for you. I need to provide you an excuse for why I named my company something other than what you thought it should be? Yeah I'll get right on that.
Just pointing out how unprofessional and uninformative it is for a licensed professional to conduct business under some Chick-Fil-a or Arbee's-sounding name. How exactly does it serve either the public interest or the profession? Doesn't.
It is a humorous notion that I would take PR advice from you Kent.
