In 2013, we were tasked with surveying a tract in an adjoining county down in a bottom. It was the bad news bears of tracts of land. We controlled our tract via OPUS (NAD83(2011)Epoch2010.0000).
Well, I needed to check if anyone had done anything in the area so I called another surveyor I knew. He had indeed been in the area and confirmed that it was the bad news bears of tracts to survey.
Well, he graciously provides me a survey they prepared. Their survey was grid bearings and surface distances and provided me coordinates (via the plat) of what they had found and set. We went and tied them in to verify.
Well, this rat sucker provided the following values on two monuments of interest to me.
The first was a 1" Iron Pipe by a road and the second was a corner they set in a bog.
First N6813420.93 E3112052.20 and Second N6810334.08 E3111607.61 which yields South 08°11'45" West, 3118.70 feet (grid).
Their survey was SO POOR in fact that after our multiple observations on the monuments (via RTK on two different days), we found on the First and Second as follows:
First N6813420.94 E 3112052.17 and Second N6810333.98 and E3111607.76 which yields South 08°11'32" West, 3118.78 feet (grid).
For the LOVE OF GOD, either my RTK didn't work any better than Thirteen Friggin seconds and 0.08 feet over 3100 feet, or they can't survey but it's APPARENT that the difference is TOO much, even though the iron pipe was by a well traveled road and the rod fell in a leaning tree and that their survey was controlled by NAD83(CORS96) Epoch 2002.0. It's too much! That's all it is! DEAR GOD what is the surveying community to do when practitioners cannot match each other better than that some 5 years apart!!!!!! The world may never heal from this!
Also, Shawn and J.D. Billings, if you can't survey any better than this, then maybe I need to hang it up! 🙂
So, as we all know by now, the tone of this post is all (mostly) in jest to prove a point in which someone we know here, who refuses to try a type of equipment, is all to quick to project their feelings on the subject, without any real practical knowledge of the equipment or procedures due to their inability to admit that they may not know everything about a subject or are unwilling to try new things, because it may mean they were wrong. This is an unsightly character flaw to be sure and probably carries over into other aspects of this individuals life. For that, I feel sad for those who must interact with him on a daily basis. I mean, surely it has to be the gear and not the ones actually using it, right? We've never followed a bad survey done before the black box was invented and poor practices and shoddy work is something that we have begun to encounter since 1995, right?
For me, I'm using RTK, Static and Conventional surveying on most of our projects, verifying cross ties, residuals, and have solid procedures that produce repeatable (less than what I illustrated above under normal conditions) results and, just happen to match what other surveyors in our area are producing who, have demonstrated their grasp and mastery of this subject matter in great detail (read OPIE from the old board). Also, I'm almost positive they didn't have RTK when they produced their survey, so that means that it had to be my RTK vectors that were wrong, right??? 🙂
The coordinates were right. I hope you set a new iron rod in the right place.
That was a tough one, built on a mix of static GPS and some nasty conventional traverse.
It's really cool that our measurements agreed that well. Your example isn't in the <5mm class, but I think most surveyors would be very pleased to agree within the 5cm you've noted, particularly in this sort of rural setting.
I keep pushing to determine what the accuracy of RTK is. I believe, based on personal testing, that it's around 5mm+1ppm RMS, at least with our current equipment. I never observed much better than that with post-processing. An average total station will do 2mm+2ppm. If my math is correct, head-to-head, a total station in proper adjustment, with atmospheric correction properly set, will beat RTK out to 3000 meters. The hitch to that is, at least around here, you can't see 3000 meters, which means traverse. Each traverse station then accumulates setup error. It doesn't take too many errors from setup and the EDM ppm (not even considering angular error), for a total station survey to be less accurate than RTK.
I stress professional discretion. Where is that point that RTK is better than the total station? As in most things "surveying" - it depends.
Professional discretion tells me that if your repeat RTK observations on those two points were in substantial agreement, I'd believe your values to be more reliable than ours on that survey (not that I consider either to be excessive in error).
I suppose that I will never ceased to be amazed over using GPS to locate a point previously surveyed years earlier with GPS (either by us or others) and hitting it within a tenth.
> For the LOVE OF GOD, either my RTK didn't work any better than Thirteen Friggin seconds and 0.08 feet over 3100 feet, or they can't survey but it's APPARENT that the difference is TOO much, even though the iron pipe was by a well traveled road and the rod fell in a leaning tree and that their survey was controlled by NAD83(CORS96) Epoch 2002.0.
Okay, so is the idea that two RTK surveys disagreed by more than 1:15,000 in horizontal accuracy? That sounds perfectly plausible. Next.
You're looking at positioning accuracies of about +/- 0.10 ft. on both of the endpoints, both for the first survey and the second and ending up with a net miss of 0.21 ft. which seems like business as usual for RTK, based upon what I see.
Might want to hold off on telling Trimble that they've underspecified the accuracy of your equipment, though. Just a thought.
I think Kris is the reason for that big error in the distance. He must have moved the 1" iron pipe when digging for it.
Stuff happens when shovels get involved. 🙂
One RTK survey.
> > For the LOVE OF GOD, either my RTK didn't work any better than Thirteen Friggin seconds and 0.08 feet over 3100 feet, or they can't survey but it's APPARENT that the difference is TOO much, even though the iron pipe was by a well traveled road and the rod fell in a leaning tree and that their survey was controlled by NAD83(CORS96) Epoch 2002.0.
>
> Okay, so is the idea that two RTK surveys disagreed by more than 1:15,000 in horizontal accuracy? That sounds perfectly plausible. Next.
>
> You're looking at positioning accuracies of about +/- 0.10 ft. on both of the endpoints, both for the first survey and the second and ending up with a net miss of 0.21 ft. which seems like business as usual for RTK, based upon what I see.
>
> Might want to hold off on telling Trimble that they've underspecified the accuracy of your equipment, though. Just a thought.
I think the real point is that it is absolutely precise enough for land surveying.
> One RTK survey.
Oh, so most of the 0.21 ft. error could have been in the RTK work? That seems plausible.
I couldn't agree more!
> I couldn't agree more!
The thing to keep in mind, though, is that relative uncertainties of 0.10 ft. or more don't meet some surveying accuracy standards, particularly when the points positioned are not widely separated.
This being the case, the problem of estimating the actual uncertainties remains an essential one if the surveyor is to certify that the work actually meets those standards. "Pretty close" is not an ALTA Standard, for example.
I'm unclear as to what 0.21' "error" is being discussed...
I'm not sure how you keep misreading plain text.
We had to traverse from static control into a swamp, and set a rod in said swamp. At the time, I can recall figuring said rod would probably never be seen again. This place is a couple thousand feet from the dead end of a pig-trail county road. Oddly enough, Kris and Co. come along a couple of years later to follow us on an adjoining tract. I didn't have ALTA/ACSM standards in mind as we did our work, I can assure you. Mostly I was wondering how many cottonmouths must have watched us from inches away as we sloshed through the fern carpeted mire. I don't figure that we produced the best example of metrology in our work, but for most, it would seem, the accuracy was more than suitable for the need (what once would have required an accuracy of +/-0.10+1:5000, before the State removed such standards). By the way, I believe that the ALTA/ACSM standard would allow for a relative accuracy of 0.13' on this baseline. Kris's allowable 0.13' and my allowable 0.13' would give us a combined allowable accuracy of 0.18'. If I read Kris's post correctly, we had about 0.20' difference in the vector between the two points. This was not an ALTA/ACSM survey, but we still came awfully close to meeting even that standard.
One more point of interest...
CORS96(2002) > NAD83_2011(2010) translation for our neighborhood is about:
N +0.01'
E +0.04'
Billings Coordinates:
N 6813420.93 (CORS96) > N 6813420.94 (NAD83_2011)
E 3112052.20 (CORS96) > E 3112052.24 (NAD83_2011)
N 6810334.08 (CORS96) > N 6810334.09 (NAD83_2011)
E 3111607.61 (CORS96) > E 3111607.65 (NAD83_2011)
(Point in Swamp)
Morgan Coordinates:
N 6813420.94 (NAD83_2011) residual: 0.00'
E 3112052.17 (NAD83_2011) residual: -0.07'
N 6810333.98(NAD83_2011) residual: -0.09'
E 3111607.76 (NAD83_2011) residual: +0.11'
(Point in Swamp)
Most mortal surveyors would be pretty pleased to find a monument in a swamp that was only "out" by 0.14'.
RTK really means
As most of should be aware, RTK now stands for
'Rolling Thunder Kris' Morgan........
he mentioned 13 seconds over 3100', so about .2', typically no problem for a larger tract survey
RTK really means
Repeated
Tedious
Kvetching
RTK Surveys, That's it, I'm calling one of you out (Shawn)
>
>
> Most mortal surveyors would be pretty pleased to find a monument in a swamp that was only "out" by 0.14'.
I'm REAL sure that this mortal surveyor was PLENTY pleased that the corner was there and that it fit as well as it did. I honestly can't tell you why I remember this job and how well we fit together on the project, but I do and I was very happy to see that it worked as well as it did. In fact, I seem to remember saying it was flat for all practical purposes.
I'll follow you any day Shawn! 🙂
RTK really means
> As most of should be aware, RTK now stands for
>
> 'Rolling Thunder Kris' Morgan........
Roger that!!! 🙂
> One more point of interest...
> CORS96(2002) > NAD83_2011(2010) translation for our neighborhood is about:
> N +0.01'
> E +0.04'
>
> Billings Coordinates:
> N 6813420.93 (CORS96) > N 6813420.94 (NAD83_2011)
> E 3112052.20 (CORS96) > E 3112052.24 (NAD83_2011)
>
> N 6810334.08 (CORS96) > N 6810334.09 (NAD83_2011)
> E 3111607.61 (CORS96) > E 3111607.65 (NAD83_2011)
> (Point in Swamp)
>
> Morgan Coordinates:
> N 6813420.94 (NAD83_2011) residual: 0.00'
> E 3112052.17 (NAD83_2011) residual: -0.07'
>
> N 6810333.98(NAD83_2011) residual: -0.09'
> E 3111607.76 (NAD83_2011) residual: +0.11'
> (Point in Swamp)
So, Kris's RTK coordinates appear to have a standard error of about 0.09 ft. in N and in E values compared to yours?
> >
>
> So, Kris's RTK coordinates appear to have a standard error of about 0.09 ft. in N and in E values compared to yours?
Ahem! That's Kris', if you please.