@john-putnam Sort of points to a disconnect between the RLS and the field crew left to figure things out on their own. In my experience a very common problem where the LS and office people live in one world and the field crews live in another and there's little by way of direct overlap and guidance. In the past I've had some major problems with field guys getting projections mixed up, knowing their data has issues and then handing it off as 'not my problem' since nobody is taking the time to work with them to show them what and what not to do. I've seen it get downright toxic when egos get involved.
Just because I'm paranoid, doesn't mean they aren't out to get me.
Yes, that's right when only a total station is used.
When Captivate's Determine Coordinate System app is used to match lat-lon to rectangular coordinates, it's different. I don't know the particulars, but from what little I can gather, Captivate can create a TM projection. Whether it always does, has to be asked to do so, or can also create a Lambert projection is beyond what I can find quickly.
Whenever lat-lon is converted to Northing-Easting, a projection has to be defined. Lat-lon is specific to a particular ellipsoid. A mapping algorithm that duplicates the math needed to convert points on an ellipsoid to analogous points on a map does the work.
Thank you for pointing that out. Not ever job requires an ellipsoid-derived plane coordinate system and Leica, for one, supports an alternative.
That is a different situation. The Determinant Coordinate System app does assume a projection, depending on the transformation technique you specify. The app can be used similarly to field calibration in Trimble speak or a true 7 parameter geodetic transformation between know geodetic control. Any time you utilize the app you end up with a coordinate system attached to your project. You can still have a project with no underlying geodetic datum and use it for total station work. I'm pretty sure you can even collect GNSS data with no coordinate system, it just does not show up until you add one. I know you can add a geodetic coordinate to a project without a coordinate system, you just don't get an associated local grid coordinate. My point was that, while rare today, not every project is on a geodetic coordinate system. Some are still on based good old 10000,5000 and a compass bearing north. That is the only time I would set my TS 0ppm.
That is the only time I would set my TS 0ppm.
Surely your total station would never be at 0ppm unless the temperature and pressure happened to be exactly the equivalent of 0ppm. Otherwise any deviation from the standard temperature and standard pressure will result in a ppm compensation in the measuring of distances.
Indeed. I've marked axes on a tile floor to teach coordinate calculations. Students calculate oblique distances from coordinates and checked their work with tape measures. That put an abstract concept into the real world and gave context to what is totally boring for many students.
You made a great point!
I'm not sure what there is not to trust about it.
It's probably more to do with not training and consequently not trusting the field crew to execute the scaling right.
Computing the combined factor is a simple math formula once you know the projection and location.
Right, though it does make me wonder why if it's simple math like that then why do the different softwares come up with slightly different scale factors when the exact same projection and location data is used in the calculation.
@lurker Geometric PPM not Atmospheric. They are input individually.
At each control point pair, if you are just randomly selecting one control point as good and adjusting the back sight distance based on the total station measurement before setting your new corners, it seems like you would be slinging error around like a short order cook slinging out fries.
I agree. Also, if you decide to reverse your setup it gets even messier.
There also seems to be some confusion as to whether the scale factor is 1.00000000 or something else.
I looked in the raw data file and the scale factor was 1.00000000. I have to investigate that further.
@murphy I bet geodesy folk will be interested in how we locate ourselves on the planet 100 years in the future, but the guy who's paying me next week doesn't give a flying flagged hub where he is. He needs to know if his long used access gate is fully within his property or not because he's got a new neighbor threatening to cut half of it out. I imagine landowners 100 years from now won't be too much different with regards to how we do what we do.
I've had many clients tell me they didn't need me to do this or that. I had an old timer furious because I insisted on locating both ends of his boundary before setting a new corner on his line. Why bother creating records at all, the landowner doesn't care, they just want to see their corner? Your argument would hold more weight if it was difficult or time consuming to get a grid tie.
If you're not using GNSS, so be it. If you're using GNSS, it's ridiculous to not copy and paste a coordinate pair on a corner or two. I'm not saying to ignore all the other important aspects of surveying. Putting state plane coordinates on one or two found monuments takes nothing away from your survey but has a potential to be additionally useful to others.
Rereading the comments to my suggestions highlights the importance of recognizing the human tendency towards binary decision making or the either-or fallacy. Folks, tieing your surveys to Earth doesn't mean your survey can't have impeccable relative accuracy too.
Plus every survey that I have done since 2005 has been on state plane coords anyway so adding a pair of coords is a no-brainer.
If you're using GNSS, it's ridiculous to not copy and paste a coordinate pair on a corner or two.
In California "pasting a coordinate pair" on a corner or two requires complying with Public Resources Code §8801 et seq., which includes (among other requirements):
8813.1. After December 31, 2005, any survey that uses or
establishes a CCS83 value or values shall meet all of the following
requirements:
(a) The survey shall be referenced to and shall have
field-observed statistically independent connections to one or more
horizontal reference stations that is or are one of the following:
(1) CSRN station.
(2) Geodetic control station located outside of the State of
California that meets all the requirements for inclusion in the CSRN
except that the station is outside California.
(3) Existing CCS83 station that:
(A) Is shown on a map filed with the applicable county surveyor by
a public officer, subdivision map, corner record, or record of
survey.
(B) Meets all the requirements for inclusion in the CSRN, except
that the station and its data are not published by NGS or CSRC.
(C) Has an accuracy, conforming to the applicable CSRN
requirements, stated for the station's value.
(4) Existing CCS83 station that:
(A) Is shown on a public map or document that is compiled and
maintained by the applicable county surveyor.
(B) Meets all the requirements for inclusion in the CSRN, except that
the station and its data are not published by NGS or CSRC.
(C) Has an accuracy, conforming to the applicable CSRN
requirements, stated for the station's value.
(b) If an accuracy is to be claimed for the CCS83 value or values
established, the claimed accuracy shall be an accuracy standard
published by FGDC or FGCS.
8813.3. (a) After December 31, 2005, when a survey that uses or
establishes a CCS83 value or values is shown on any document, the
station or stations to which the CCS83 value or values are referenced
and connected and the CCS83 value or values and the published or
stated accuracy or accuracies of that reference station or stations
shall be shown also on the document.
(b) If a CCS83 survey begins before January 1, 2006, and is not
completed by that date, the CCS83 survey may be completed in
accordance with Sections 8813 and 8815.4 of this chapter or Sections
8813.1, 8813.2, and 8813.3 of this chapter, at the surveyor's option.
All other applicable provisions of this chapter remain applicable.
That's a descent requirement. Basically you'd just need to show metadata and provide the coordinates and accuracy from a nearby CORS. I can understand hesitation to provide something that's not required but has strict rules. My preference for a grid tie aside, reviewers have succeeded in making me strip plats down to the bare-bones to avoid their ire.
In California "pasting a coordinate pair" on a corner or two requires complying with Public Resources Code §8801 et seq., which includes .....
All of which effectively prevents showing coordinates on a map in CA. But don't forget to add a Prop 65 warning label.
@jim-frame Licensed and using survey grade equipment but can't even use my own stuff on site to determine coordinates? How stupid.
If it's a grid/ground difference, your boss is having you add error into your network with this practice (GPS producing grid coords, TS or DC scale factor set to 1.00000). If that's not the issue, then your boss is simply having you paper over unresolved discrepancies in your project control.
Either way, not good practice.
I've had many clients tell me they didn't need me to do this or that. I had an old timer furious because I insisted on locating both ends of his boundary before setting a new corner on his line. Why bother creating records at all, the landowner doesn't care, they just want to see their corner? Your argument would hold more weight if it was difficult or time consuming to get a grid tie.
I'm not knocking your comment at all. It is interesting to wonder how tech will change in our field in 100 years. It may be that we have everything so locked down through CORS, Satellite and AI that you just go to Home Depot, buy a $90 device (only $15 off Temu) and it will guide you to your corners, setbacks and easements without any outside influence. Neighbors would no longer have these tense disputes - it seems that many times they're mostly fueled by the unknown costs of hiring a surveyor and lawyer. Maybe they'll look back and just recognize how easy it's become compared to the old days. Surveyors may just become legal advisors. IDK
But I do think that even if we aren't there in 100 years, they'll always be able to look back like we do now, follow in our footsteps and recreate long standing boundaries from the information we currently leave. I certainly wasn't suggesting we nove toward relative precision only just because that's what the client needs right now. That precision already goes hand in hand with with a pretty accurate lat-long or derivative thereof in everything we do (hopefully), certainly by law and practice in this state. And it'll continue like that with, I'd bet, the acquisition of that info becoming radically simplified.