Setting aside the subdivision boundary, would you tweak (pin cushion or remove and replace to the record distances) the original RTK set markers (out of measurement by a tenth or two) in the interior of the subdivision or consider them original monuments and hold them where they were set (note the difference in your measurement and the record distance)?
> Setting aside the subdivision boundary, would you tweak (pin cushion or remove and replace to the record distances) the original RTK set markers (out of measurement by a tenth or two) in the interior of the subdivision or consider them original monuments and hold them where they were set (note the difference in your measurement and the record distance)?
Is that a serious question? Surely it can't be.
> > Setting aside the subdivision boundary, would you tweak (pin cushion or remove and replace to the record distances) the original RTK set markers (out of measurement by a tenth or two) in the interior of the subdivision or consider them original monuments and hold them where they were set (note the difference in your measurement and the record distance)?
>
> Is that a serious question? Surely it can't be.
Is this a serious reply Kent? Surely it can't be!
> > > Setting aside the subdivision boundary, would you tweak (pin cushion or remove and replace to the record distances) the original RTK set markers (out of measurement by a tenth or two) in the interior of the subdivision or consider them original monuments and hold them where they were set (note the difference in your measurement and the record distance)?
> >
> > Is that a serious question? Surely it can't be.
>
> Is this a serious reply Kent? Surely it can't be!
Yes, it's a serious reply to about as idiotic unserious a question as I can imagine someone who claims to be a surveyor asking. "Do the monuments placed by the original surveyor as shown upon the record subdivision plat control the positions of the lines and corners marked by them?" That's what the question amounted to. It can't be a serious question.
I suppose that a couple of tenths difference from the record doesn't really matter then does it? So why all the complaining?
And you are welcome to your opinion that I'm not fit to claim to be a surveyor. Don't worry, I have no intention of ever applying for a Texas LS license.
Retracing the ORIGINAL Subdivision Survey
Here's a serious question:
Is there a differance between this plat and a similar plat, surveyed in the 50's or 60's?
> I suppose that a couple of tenths difference from the record doesn't really matter then does it? So why all the complaining?
LOL. The record distances were apparently on the GRS80 ellipsoid, but with absolutely no mention of that fact. So the scale discrepancies averaged about 132ppm. Add in the 95% confidence uncertainties of about +/-0.24 ft. at the end points and it's the sort of work that you pretty much need RTK to mess up that badly.
> And you are welcome to your opinion that I'm not fit to claim to be a surveyor.
No, I was giving you the benefit of the doubt by assuming you weren't serious in asking the question. It was Loyal who thought that you didn't know whether the original monuments shown upon the record subdivision plat fixed the lines and corners.
Retracing the ORIGINAL Subdivision Survey
> Here's a serious question:
>
> Is there a differance between this plat and a similar plat, surveyed in the 50's or 60's?
Yes, the older plat would have typically had much better local accuracy and would have been comparable or better in distance measurement accuracy (until you realize that the RTK survey was reporting distances that most likely refer to the GRS80 ellipsoid, and were not horizontal surface distances).
Retracing the ORIGINAL Subdivision Survey
> Yes, the older plat would have typically had much better local accuracy and would have been comparable or better in distance measurement accuracy (until you realize that the RTK survey was reporting distances that most likely refer to the GRS80 ellipsoid, and were not horizontal surface distances).
Let me rephrase my question:
Would you treat an error, found in an original 1950's subdivision, any different that you would treat one in the JackLeg RTK plat?
Retracing the ORIGINAL Subdivision Survey
> Let me rephrase my question:
> Would you treat an error, found in an original 1950's subdivision, any different that you would treat one in the JackLeg RTK plat?
Well, it would depend upon the nature of the error. Some errors in surveys made in the 1950's and 60's would be so extraordinary as to suggest that a monument had been moved, for example, but could just well be business as usual with RTK.
For example, the centerlines of roads would typically have been traversed in the transit and tape era. That meant that alignments were usually pretty good and widths of rights of way likewise.
A record distance around here is on paper (mostly scanned) in the recorders office. How is was placed in the record by a surveyor, landowner, whatever, can be the subject of speculation. On the ellipsoid would be different than ground or SPC. Some of the record distances I deal with where never measured (hacked at adesk from a previous made up record and other pure PLSS mathematical magic). If you are lucky enough to have markers described in the record then the record distance is just a pointer. Some pointers are better than others. Any error ellipse less than 5 feet should be a piece of cake if there is a marker (monument). A tenth of two in most places is nothing. Some places in the PLSS the error ellipse might be hundreds of feet. I suppose we can complain all we want but we hunt for the monuments and when we find them we hold them as the original lines. So much for the record, eh?
RTK has some slop in it but it's still a highly productive and amazing tool. It's plenty good for me and my clients and my mostly rural setting. These folks wouldn't pay a lot more to work the last couple centimeters or so out of the survey. A foot would probably suit most of the surveys I do.
What did the surveyors of 200 years ago complain about? The previous guys pacing was bad? Actually there is measurement equipment available much more accurate than survey grade total stations. Why not use that and get all survey work under a millimeter. We could get the minimum boundary survey to $25,000 and go up from there.
> I suppose we can complain all we want but we hunt for the monuments and when we find them we hold them as the original lines. So much for the record, eh?
Not really. When monuments are destroyed, if the record of the original survey is the best evidence that remains of where those corners were marked, then the record is pretty important. So, the subdivision plat with large errors in it becomes the gift that just keeps on giving over time if one has to resurvey a good bit of the subdivision just to figure out the situation and interpret the faulty record. Large random noise in the survey as RTK can so readily offer definitely doesn't help unless you're just there for the entertainment or the GIS.
Retracing the ORIGINAL Subdivision Survey
> Well, it would depend upon the nature of the error.....
Life must be good in Texas B-)
A few of the plats from the transit and tape era, that I've run into, were, shall we say; less than desirable. You're lucky to live in a state that that doesn't happen.
:snarky: (best regards)
Douglas
Retracing the ORIGINAL Subdivision Survey
>
> A few of the plats from the transit and tape era, that I've run into, were, shall we say; less than desirable. You're lucky to live in a state that that doesn't happen.
Oh, there were bad surveyors in the 1950's. I was describing the way that the competent surveyors laid subdivisions out in Central Texas. Some of their field books exist and show how things were done. The rest can be deduced from what remains in the ground of their footsteps.
The display shows how many degrees the unit is out of plumb. I am hoping they will update it so that when it is less than 1 it reads to the nearest tenth so the unit can be plumbed more precisely.
Retracing the ORIGINAL Subdivision Survey
> Oh, there were bad surveyors in the 1950's. I was describing the way that the competent surveyors laid subdivisions out in Central Texas. Some of their field books exist and show how things were done. The rest can be deduced from what remains in the ground of their footsteps.
You keep dancing around my original query, Kent; do you treat the bad surveyors of the 50's with different respect than the bad surveyors of today?
Retracing the ORIGINAL Subdivision Survey
> You keep dancing around my original query, Kent; do you treat the bad surveyors of the 50's with different respect than the bad surveyors of today?
What does respect have to do with anything? If a monument is an original, undisturbed monument, it's an original undisturbed monument regardless of my opinion of the surveyor responsible for it.
With modern technology, competently used, it is possible to determine the positions of things so well that the position alone is a fairly good test of whether the monument is undisturbed. Obviously that doesn't hold for the haphazard RTK work where the random noise level is high.
In the case of a survey made sixty years ago, the same evaluation applies, namely, whether the old iron pipe that appears to be an original mark of that survey is in its original position or not. The competently made surveys from the 1950's are in my opinion easier to evaluate than some late-model RTKing with high random noise and a large scale error. In other words, functionally the modern RTK work is significantly worse than the 1950's-vintage transit and tape survey.
Retracing the ORIGINAL Subdivision Survey
:good:
Large random noise in the RECORD is several magnitudes larger than a sloppy RTK survey where I work. The record can get you 10, 20 or more feet away from an established boundary. So a couple tenths slop in RTK seems mostly insignificant. Must be great to work where a major worry is a couple tenths. When you get down to only the record to go by all evidence of boundary is gone, the boundary location is lost.
Retracing the ORIGINAL Subdivision Survey
There are several reasons to reject an original monument; math isn't one of them.