Error Errors and Errors
> Well, if you know my response, then you know that I think a professional surveyor should be interested in some on-going assessment of survey measurement process quality. positioned.
https://surveyorconnect.com/index.php?mode=thread&id=159934#p160308
> > I'm sure it was a typo. We all know that 4-hundredths is the minimum standard
>
>
> 0.04' was a Nineties thing..we all know that it is hundredth or two nowadays. |-)
Hmmm....I'm not sure you have been reading this thread. A hundredth or two...on the same day or on different days with different weather conditions and different satellite constellations? Did you actually do a scientific study or is this just an anecdotal report? Is that a hundredth measured against a calibration baseline? ....hmmm...Now let's start all over. I think we've come full circle.
Is it possible to analyze with anal eyes?
Error Errors and Errors
>> https://surveyorconnect.com/index.php?mode=thread&id=159934#p160308br >
Well, this thread is specifically about the actual performance that a real network RTK documented. It shows how you can actually figure out whether the uncertainties in RTK positioning meet some common specifications for relative positional accuracy or *not*. I realize that there are plenty of RTK users who haven't really thought very hard about whether the methods they're using meet any specification at all. No surprise there.
RTKALTA Selzer
> "If I use it and save too much time and do not use all of my budget then I will be given a smaller budget next year"
> (now retired)
>
> "I can charge my customer more if I use [terrestrial]"
> (different company but now involved in scanning)
And there you have it all summed up:
What is wrong with most government agencies
AND
what is wrong with our profession or stated another way why most surveyors aren't good businessmen, they charge by the hour instead of value pricing their work. Is the survey any less valuable if it takes 1/2 the time to perform? No, especially not if you spent a boatload of money to cut your time in 1/2!
SHG
Surveying Errors and ALTA... Idea!
I'd rather see a less precise measurement to the right place than 10 on a nats butt to the wrong place. With all this all so precise measurements it might just lead to more precise pin cushions. I suppose I'm just more concerned that the surveyor actually finds the legal boundary than lays out the deed to the highest precision. Yes surveyors should be able to make accurate measurements but it's way down the list from locating the correct boundary. The correct boundary measured to say a couple of tenths is more important than all the other lines one can dream up and set at a hundredth.
How often are the measurement specs checked and challenged for an ALTA survey? How many surveyors end up in front of their board for being a bit out of spec? If you end up in court it will likely be over the location of the boundary and not the measurement. You will probably end up deeper in the water in a construction layout for a blunder or little error than any other. In that case all they want is compensation.
What I don't get....
:good:
The Dog Ate My Relative Positional Uncertainty
> Is it such a toxic questiuon to even consider that to some degree we may be unduly burdening ourselves and our clients?
Being able to determine the relative positions of two boundary markers with an accuracy of +/-0.07 ft. + (50ppm x D) (95% confidence) is a really, really tough specification that no surveyor should be expected to be able to meet without breaking a sweat. However, good news, there's an EASY button.
The ALTA specification thoughtfully provides that if a surveyor can't meet the accuracy specification, all he or she needs to do is explain why. I'm sure that won't be a challenge.
"I was not able to make a good enough survey to determine the positions of markers designated as "A", "B", and "C" sufficiently well to meet the ALTA relative positional accuracy specification because ___________
___ the batteries went dead on my RTK rover and it would have meant that I would have to drive back to the site the next day, but I had told the man that I would be at the other job so I could not get back to the site.
___ the client had told me that they did not care if the measurements weren't very good since it had never been surveyed very well and they did not see why it even needed to be surveyed one more time in the first place.
___ all of the boundary markers was buggered up pretty good and I couldn't see how I could even put the pole on the same spot more than once.
___ this township is all messed up and nobody really wants to pay for anything being surveyed very carefully and if I was to survey this one carefully then all of the other people would expect me to do that as well.
___ I could not get the RTK rover pole right on the marker that I am showing on the map as marking the corner so I held it pretty close or at least as close as I could get it and I figure that has to be good enough because to do it any better would have required me to set some offset points to locate the marker from and that could be real confusing.
___ the ALTA relative positional accuracy specification makes my head hurt bad and I'm out of aspirin."
The Dog Ate My Relative Positional Uncertainty
> You could have written that and substituted RTK for almost any other tool.
Well, I thought that since the RTK enthusiasts were complaining about those dastardly relative positional uncertainty standards that it was a no-brainer that they realized it was a problem mainly for RTK.
I mean, the topic of this thread is evaluating some network RTK results that were posted to determine whether the positional uncertainties they reflect from 240 seconds of network RTK positions would meet the ALTA specification or not. So it is pretty much an RTK sort of thread. If someone wants to start a thread on the subject of whether they can meet ALTA relative positional uncertainty standards with a Sears Craftsman Builder's Level, I'm sure that there will be plenty of posters extolling the virtues of their old Sears instruments that they hated to trade for RTK. But the RTK will just be mentioned in passing, one would hope.
Your Dog Wants to call it an ALTA?
> The results are excellent, and there is no reson why cadastral work should not be done with such tools through careful practices. Is there such a lack of imagination and innovation that such tools (and some to come) cannot be leveraged to improve instead of being rejected outright over a very narrow set of cirteria that may be doing more harm than prventing some kind of harm?
Well, the basic critique is a simple one (or so I had thought), that to be useful in land surveying black box positioning needs to have the uncertainties in the output positions well characterized. It struck me originally as painfully obvious as it does now.
Instead, what has passed for a response has included the idea that RTK is obviously good and should not be subject to the same scrutiny that any other survey measurement technology is (that's obviously a paraphrase, but that's pretty much what it all amounts to). Either that or lots of surveyors use it and it wasn't available twenty years ago, so obviously it is beyond any question as to its suitability for land surveying (another paraphrase that preserves the spirit of the advocate). Or, finally, that the expectations that new technology ought to deliver results as good as the old technology needs to be changed because it is too hard and ... stuff.
The point of bringing up objective specifications and error budgets that exist outside the desire of a surveyor to work at warp speed is that "good enough" isn't a subjective standard unless you want to get good at writing funny excuses to put on ALTA Land Title Surveys why you weren't able to carry the extremely, very, back-breakingly heavy burden of actually ... meeting the specification as you'd contracted to do.
> All you did was show that one school of thought holds that a hundreth is valued above all considerations of actual risk and cost-benefit.
Yes, the trend of anyone who only has a hammer is I'm sure to wonder why anyone would be so inconsiderate as to use screws or bolts as fasteners. The desire of RTK users to just argue that some specification that anyone else can easily meet is just too terrible a burden for them is just that.
No reply
> Your abilty to stare someone down is admirable ...
Well, if you consider reminding posters of the subject of the thread to be "staring them down", all I can say is "huh?". I don't have much patience with faith-based approaches to land surveying.
I have done stuff like this in the past. It would be interesting to take an object, say an open pipe, leaning would be even better, or an iron rod with cap, set up your instrument, set it up well, then set up a tripod/tribrach/prism over the pipe, shoot it, take it off, set it up again, shoot it, etc. see what kind of repeatabillity you could get. Course we sort of do this with every survey we do.
No reply
this is all getting somewhat laborious. Are you suggesting that the standard errors of RTK/RTN cannot be deterimined? Or that the standared errors will always exceed the allowable errors?
No reply
> Are you suggesting that the standard errors of RTK/RTN cannot be deterimined? Or that the standared errors will always exceed the allowable errors?
So, you've read this thread and are asking this? What did I post?
No reply
you've posted a lot. However, it's difficult to ascertain exactly what your rub is.
RTK bad? Static good?
Is RTK testable (non faith-based)? I believe it is and have done so, several times.
I've done so much testing that while testing new receivers now, I have a pretty good "gut feel" of what to expect before formal precision testing. That precision testing has shown me that RTK can provide results as good as static. I'm not convinced of RTN in my area (it does exist... barely). My testing has not produced the level of precision I require. HOWEVER, RTN's vary greatly from one system to the other. The level of maintenance is crucial to the quality of the network.
I do believe that we are a long way from abolishing ground monuments to proof system integrity. A surveyor has an obligation to methodically test his equipment to insure it provides the requisite level of precision. I don't believe anyone has argued the contrary... which leaves me flumoxed as to your actual point of contention.
Would you like to look at some of my spreadsheets from receivers I've tested?
Alps and Beaches or experts who do not use...
(Aside:) Hey, cool new avvie! Now where have I seen that graphic before? 😉