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Working for a Surveyor that does not understand GPS.
Posted by Cosmolabe on March 8, 2023 at 7:28 pmThe surveyor I work under does not have a clear understanding of working with GPS or using Grid Coordinates. When I started working for them a few years ago everything was all total station and levels from Geodetic or hiring someone for a couple GPS points on the sites we did stakeout on. Until recently we had not planned on changing that. Now after a demo from a Survey Supplier we are getting some Carlson Rovers to be used in place of the total stations for some of the work.
After some recent conversations it has become apparent that they intend for me to be the one to learn all the ins and out and how to process the data into recordable maps.
I recently graduated from an Associate’s program in Land Surveying but we did not go very deep into this topic beyond what might be covered on a board exam and some field procedures. I have used GPS before but never in an application like producing plats.
I feel that I could learn the procedures to do this task but I do not feel comfortable enough with it at this time.
How should I approach this topic professionally?
jflamm replied 1 year, 5 months ago 24 Members · 56 Replies -
56 Replies
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Make sure that your company provides you with all the training that you need. If you do not have a clear understanding of the equipment, when and when not to use it, how to use it and how to process the data, you are only going to create problems.
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You have the opportunity to say this is what I need to become competent. They are not competent and can’t teach you. If you want someone to take the initiative to make you competent, you will probably have to go somewhere else. If you have the initiative to make yourself competent, then this is the perfect opportunity. Dive in and make it happen or wait on someone else to make it happen for you.
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Grab the bull by the horns and make yourself valuable to that company and anything that may come in the future, if you so desire. You just got out of college so your brain is already in the right mode. Don’t wait till down the road when things may be more difficult. There are Chiefs at my current company that have been at it for 30+ years and they can’t even spell GPS. It’s quite sad. There’s plenty of training and help out there.
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They better be willing to pay for every minute of training you need, as well as throw in a nice big pay bump for you taking this on.
As a side not, I’d be more than a little concerned about a licensee who thinks “oh I’ll let an employee learn this decades-old industry-standard technology rather than learn it alongside of them“.
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman -
Just about any surveying work you’ll encounter is going to require a working knowledge of using GPS. Old school conventional is also important but these days the emphasis is on the efficiency GPS brings to job. A good book to start with is GPS for Land Surveyors by Jan Van Sickle. It details the different methods used. This site is also a good place to ask specific questions. It’s good to put yourself out there and learn but know that like any tool, there’s always different ways of using it and it’s in the understanding of the tool and they systems behind it that you develop the knowledge to know when and how it’s appropriate to use and the limitations that come with those various methods.
Willy -
https://www.publications.usace.army.mil/usace-publications/engineer-manuals/
see EM 1110-1-1003 NAVSTAR GPS Surveying
free PDF
I find the USACE manuals to be useful as they are written to teach often under prepared learners. Lots of good free presentations on GPS/GNSS. I recommend Eric Calais’ when he taught at Purdue.
obviously you need to study the materials provided by your equipment manufacturer.
You also need some background on geodesy.
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You do need a basic understanding of what the satellites are doing, what data you receivers are collecting and what calculations and conversions your data collector is making. There are a handful of good correspondence courses out there. They are mainly for continuing education credits, but they do provide the basic idea. There seems to be more things that will degrade your position using GNSS than with conventional total station data collection. You need to formulate a good procedure for verifying that the data you bring into the office is correct. Some sort of supplementing your Single Base Line RTK with Static GNSS, Conventional Control, or Network RTK. Good Luck.
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I’d be hard pressed to teach myself GPS if i started GPS work today. You definitely need someone that has done it before to show you the processes and procedures. GPS configurations and coordinate systems and scale factors can be very efficient or create more of a mess than anyone can fix.
Not all that long ago we had received data from another survey firm for a municipal project. It was clearly done with GPS and things were going along just fine until we checked into some of their primary control points and missed by 5′! Other points were spot on, the primary control wasn’t. To make a long story short they scaled the project data down to ground using a central project point (I despise this method with a passion!!!) but did not scale the primary control points. There were other systematic issues as well, but that was the big one. And….they had been using GPS for over a decade but had no clue of how to properly setup project scale factors and admitted as much to me along with a story of how they almost owned an apartment complex because of this issue on another project.
Getting off topic here but you really need to learn from someone who knows the ins and out of your equipment in the office and the field.
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Hi I saw this post. Before I give you a good solid answer (opinion), may I ask some questions ?
So, you’re using Carlson “rovers” ? or is it s Base and Rover ? Next off, what software and data collector has been provided ? and thirdly, there is mention of “grid” coordinates. Does this firm intend to do maps in state planes coordinate values with a scale factor and rotation angle ? Etc or are the surveys simply ground, straightforward maps / topos etc ?
Please get back with me. I’ll do my best to give you some answers and direction. Just being tossed into the lake and told to swim is NOT a good beginning.
Thanks “Good”
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can be very efficient or create more of a mess than anyone can fix.
That is so true.
I’ve been doing it for over 10 yrs.
And I’m still learning.
Not to scare you, but I honestly suggest you work with someone who knows it well, for a month or two.
There are many basic things that are best not learned “the hard way”.
I’m super pedantic, and double check all things that show signs of needing it.
And, mfr’s don’t all approach the same problem from the same viewpoint, or mechanism in their software.
Get a good mentor, even for a day a week, and you’ll not regret it.
N
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they intend for me to be the one to learn all the ins and out and how to process the data into recordable maps.
What office software is currently in use with this surveyor?
Learning it all at once could be a challenge. Do you have any experience with any kind of drafting software?
This is alot to learn.
N
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Ive got close to 160 hours of full up from PLS taught vendor specific training in Bentley and Trimble, and can honestly say about 50% is stuff I already knew, but the stuff I did learn was esoteric to the hardware’s and software and it’s worth the money to not waste your time learning on the fly. some mistakes you’re not going to be able to get fixed by getting a more knowledgeable person to work with it
they need to get you the proper training you deserve for taking this on.
period.
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They better be willing to pay for every minute of training you need, as well as throw in a nice big pay bump for you taking this on.
Eh, I get your point, but there are times when the opportunity is there for the taking, and the extra dollar means less than the chance to expand your knowledge base, and make yourself vital to this company or the next
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The vendor training will get you a jump start on the data collector and rover but usually doesn’t teach the math underlying concepts of satellite positioning and grid to ground. They assume you know all of that and here is what button you push to get to what you need. Every one here has stated very clearly what all is needed. I think if you get the training for underlying concepts down and how to get the software to do and be able to check what you want you will be fine. Its a firehose you will be going through. Geodesy for the layman is a good free download. NGS. On that site is also some free webinars that were pre recorded on datums and some basic geodessy as mentioned above. Grid to ground What state are you in? You can look up also on NGS site the publication of that states coordinate system so you will know if you are dealing with a Lambert Connical or transverse Mercator. Scale factor was mentioned but you also need ellipsoid factor then combined factor. Scale factor and ellipsoid or sometimes called elevation factor make the combined factor. These terms you need to understand. Geoid model as well. With gps or gnss you will need this understanding. Ellipsoid and geoid heights are not elevation. I think the support at carlson would be on my speed dial. They have some great support and good training presentations as well. Tap into that as soon as possible. Don’t let all of this scare you. You can learn it. Do lots of redundancy checks. Set some points measure them with total station until you get the feel of everything down. Know your difference of ellipsoid vs elevation height rough that will save you check with opus or known monuments. To make sure you are on datum. Depending on state know if you are a us survey foot vs international foot. On which datum. Nad83 nad27 etc. even some cities and counties withen a state have there own systems. Know ngvd29 vs navd 88 vertical datums. Look up PDOP VDOP GDOP. Terms for GPS rms precision values vs accuracy. Precision vs accuracy. You are coming in as things have changed dramatically in the Gnss world. You will see more satellites at any given time than they even had in the sky when i started. This site will be a tremendous help. Very knowledgeable people here. And all are willing to help. We are all learning together. Always.
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There is a HUGE difference between using something almost every day and understanding EXACTLY what is happening and why. Your mentor needs to be someone competent, not necessarily someone who has a lot of experience but little knowledge.
We now have surveyors who are writing descriptions that will not agree with what they find already in place. The reason is as simple as assuming any State Plane coordinate is perfect to be used over and over for different projects that are not a part of the first project. We now have people not recovering existing monuments that were visited once some number of years in the past, as the thought is that there is no need to do so. In PLSSia this leads to moving coordinates from one section into controlling those in other sections, incorrectly.
We are also finding descriptions that are too long or too short on certain courses as one is written in grid and one is written in ground. Or some factor was applied to one but not the other.
The same firm may show record bearings that vary greatly from “new” bearings when following their own work from a few years earlier due to the difference between which “system” of North is involved,.
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While it’s nice to know something about how GNSS works, your immediate need it to be sure you understand the coordinate systems and projections involved. You should have had some exposure to this in class.
GNSS receivers do their calculations in earth-centered XYZ coordinates and the receiver or data collector can convert to other representations. To end up with ground distances, you will need to use either State Plane Coordinates, UTM, or a custom projection to get the numbers you need out of the hardware. If it isn’t a custom Low Distortion Projection (a very useful tool) you must know how to convert from the plane projection to ground distances that are compatible with total station data.
Get that workflow going and then worry about how the GNSS works.
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you must know how to convert from the plane projection to ground distances that are compatible with total station data.
An excellent point!
MH
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