ALTAs & RTK

I took my Leica RTK to the calibrated baseline - the results were impressive.

I would suspect they will ship out their QC report generated with their RTK DC.

That would probably wow most attorneys asking for it.

But, if you locate all the monuments twice and adjust them Trimble will create an impressive report that should satisfy most anyone.

Are there some kind of ALTA police out there? I've never encountered anyone asking for mathematical proof of monument accuracy.

play the game any way you like.
I opt for Personal Integrity...
if the ALTA standards are being complied with, fine
have Proof* of verification in your pocket and move on.

*if you Can't please be honest with yourself

Whether our data are RTK, NRTK, static, PPK, total station, taping, etc., relative positional precision is evaluated by the prescribed method per ALTA/NSPS standards - a properly weighted, minimally constrained least squares adjustment yielding error ellipses at the 2-sigma level.

Vectors are vectors, whether from RTK, NRTK, static, or PPK. (Or reduced mark-to-mark vectors from conventional data, for that matter.)

WA is poised to modify our statutes, to require surveyors to explicitly state the relative accuracy achieved and the method used. Our statutes also require that we utilize relative accuracy when data are not amenable to evaluation using traverse standards, so basically anyone incorporating GNSS in a survey is required to evaluate using RPP.

Personally, I would love to see this go through, because I do not like seeing the boilerplate "this survey meets traverse closure standards" next to a statement that says "this survey was performed using RTK and total station", and then finding out that there's something seriously screwy about their bearings & distances.

Forcing surveyors to explain what they did helps me see right off the bat whether someone knows what they're doing with respect to RPP and adjustments, and whether I can expect to come close to their values or not.

Don't even need redundancy to run that report in TBC.

How does one prove compliance with the positional accuracy requirement?

A properly weighted least squares adjustment report. Also- note that the loop closure of a classical traverse does not fulfill the requirement. You need a properly weighted least squares adjustment report for that, too.

@rover83 What Least squares software do you use?

Trimble Business Center for 98% of my work, StarNET for the rest.

(That's mainly because we're a full Trimble shop, so there's not much point to exporting and transforming to a different format. Unless something goes horribly wrong and I have to manually mess with the data, at which point I'm more likely to get a crew back out there and reobserve.)

I am with @rover83 and @Norman_Oklahoma A properly weighted LSA minimally constrained and I also use TBC and run the ALTA RPP report. Even when not doing an ALTA static rtk robot i use all the tools a lot on jobs and I just run that RPP report and it gets saved with all projects regardless. It’s an extra piece of mind and a indication if i might had missed some in the Network Adjustment Report as well. I will often crank down the RPP from ALTA standards of .07 + 50ppm just to get something to fail between control and property corners so it makes me take a look at that data and such. Make sure i did miss something. Doesn’t take but a second is all.

OK, I think I get the whole minimally-constrained-least-squares-adjustment thing. I've been adjusting conventional traverses, with OPUS static as control on traverse points, in Carlson SurvNet since 2009. Lately I've been dipping my toes into base-rover RTK, but I cannot for the life of me get SurvNet to like my rw5 files. Any SurvNet users out there who adjust RTK "traverses"?

Thanks!-SS

Edit: My remembery is failing; I just went thru my files and the earliest SurvNet project I could find was from 2013, so 10 years, anyway

Javad software had a PLS from Kentucky on the development team and Kentucky has Relative Positional Accuracy requirements for boundary work. They managed to incorporate a nice bit of massageable software that will do the heavy math lifting and provide a report.

I cannot for the life of me get SurvNet to like my rw5 files

I can't give you a specific answer, but I can point out that rw5 files are generated by at least 3 dc softwares that I know of (TDS/Survey Pro, Fieldgenius, and SurvCE). They are very similar, but not identical. Different enough that StarNet has different converters for each.

So after reading these responses, I'm curious...how many of you provided reports justifying what you did pre-GPS? And how many of you reviewed/evaluated/etc reports from other surveyors pre-GPS?

I have never provided the LS adjustment reports for an ALTA, but I do have them if I was ever asked to.