I ditto TBC for adjustments. I was a heavy StarNet user but in 2018 I had a traverse with hundreds of setups and TBC made finding bad angle sets very easy (I have a minimum of 4 sets and sometimes more because I hit set + in the field when I have a loose set). TBC has greatly improved over the past several years.
I view LSA as a processing tool that allows you to use all of your measurements to derive the best coordinates for a given point. The other way is use whichever measurement happens to be first for a coordinate and the rest for a check, that is kind of arbitrary. The measurements aren??t being adjusted so much as being fit together with minimized changes.
If my data can go into TBC or StarNET, TBC is way faster ...
That's a major thing. StarNet accepts data from a wide variety of collection programs. I've not used TBC, but I expect that it is restricted to Trimble format data.?ÿ?ÿ
Not exactly true.?ÿ I know TBC wil at least accept data from Leica and I think Topcon Levels, and can also do Static GPS networks with pretty much anything if converted to RINEX.
Still not sure about other total stations as I haven't had the opportunity to try any since we got TBC and haven't really had the time to look.?ÿ
I'm also fairly sure it will work with other types of scanners.?ÿ
I know TBC wil at least accept data from Leica and I think Topcon Levels...Still not sure about other total stations
If there's an easy way to get SurvCE data into TBC, I haven't found it yet, so Star*Net is still my go-to when TS data is involved.?ÿ For pure GNSS networks I'll sometimes adjust in TBC, but other times I'll run it through Star*Net because I'm just more comfortable with it.
For normal, standard stuff i don't get you guys still use an adjustment routine in the office. I see all on my data collector and it gives immediate errors. If the error is too big i cannot continu.
The error you eliminate (a few mm's) by adjusting is immediate back by not holding your rod completely level for detail points.
Also with resection routines and rtk gnss for setup points, who still does it the old fashioned way? All is mentioned in the field.
I just import my xyz list with coding in my survey package and continu drafting.
@beuckie?ÿ
Not all field personnel have the same skill level as you.
I'd be fine with you running a DC adjustment on a one off project that you took lead on.?ÿ However, if it was a larger project involving multiple crews with differing equipment, I would not want a variety of adjustments and reports.?ÿ?ÿ
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@murphy That is right on point. ?ÿSkill level and how many different people and equipment on a job and what is the job scope. Or requirements. That dictates what needs to be done. If you are doing some topo in the woods or rough terrain it is not as important as where the topo is done when it is tying into the existing curb and gutter or roadway intersections. Have a site right now with some old buildings that will be demolished I don??t sweat the location very much because it is being removed. Where I tie into existing roads and drainage pipes etc I want those to be spot on for design to match so I am not back out trying to field adjust when staking out in the future. Not everyone that surveys just automatically knows all of this. Thats why mentoring is important and explaining when we are building a watch and when we are not to those under our care. Topo is not always just a topo it depends on why and what is going to be done after that becomes important on how to approach the job.?ÿ
You said it correctly for sure.?ÿ
Wholeheartedly agree.
I don't know of any field collection software that runs LSA, outlier detection or blunder trapping for multiple days of fieldwork across different crews.
It's pretty common for us to have GNSS NRTK vectors that can have up to 3-5cm of error in H/V, total station observations that are more on the order of 3-5mm, and level observations that are more like 1mm or less. Our primary link to the NSRS is through the RTN stations and NRTK vectors, but we have higher-quality terrestrial data that needs to be properly weighted. If we're running base/rover, we're likely going to need to post-process to get an updated base location anyways.
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The bottom line is, analyzing data and adjusting final positions is best practices and gets you the best quality data, and is not a high bar to clear with today's computing power and multitude of available software suites. If field data is not rife with errors and mis-labelled points, I can crank through the QC and network adjustment in an hour (sometimes way less, as in 5-10 minutes) for a basic control network plus observed monuments.
It's also required on certain projects to ensure you have done your due diligence and meet minimum standards. ALTA/NSPS (and boundary work here in WA) have minimum relative accuracy standards. While I may have a pretty good rough idea of how good the work is, I'm not stamping that survey until I know for sure that certification is correct and I do meet those relative accuracy standards - which means running LSA and getting those error ellipses, because without them we can't know for sure whether we meet standards..
Most of the complaints and scoffing about LSA, at least within my own firm, come from folks who are ignorant of what it is and what it does, or from folks who are not technically competent plus insecure about using post-processing software.
Wholeheartedly agree.
I don't know of any field collection software that runs LSA, outlier detection or blunder trapping for multiple days of fieldwork across different crews.
It's pretty common for us to have GNSS NRTK vectors that can have up to 3-5cm of error in H/V, total station observations that are more on the order of 3-5mm, and level observations that are more like 1mm or less. Our primary link to the NSRS is through the RTN stations and NRTK vectors, but we have higher-quality terrestrial data that needs to be properly weighted. If we're running base/rover, we're likely going to need to post-process to get an updated base location anyways.
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The bottom line is, analyzing data and adjusting final positions is best practices and gets you the best quality data, and is not a high bar to clear with today's computing power and multitude of available software suites. If field data is not rife with errors and mis-labelled points, I can crank through the QC and network adjustment in an hour (sometimes way less, as in 5-10 minutes) for a basic control network plus observed monuments.
It's also required on certain projects to ensure you have done your due diligence and meet minimum standards. ALTA/NSPS (and boundary work here in WA) have minimum relative accuracy standards. While I may have a pretty good rough idea of how good the work is, I'm not stamping that survey until I know for sure that certification is correct and I do meet those relative accuracy standards - which means running LSA and getting those error ellipses, because without them we can't know for sure whether we meet standards..
Most of the complaints and scoffing about LSA, at least within my own firm, come from folks who are ignorant of what it is and what it does, or from folks who are not technically competent plus insecure about using post-processing software.
I went out with another crew. They worked together and I worked by myself. 2 days of Topo. TS & RTK. The night before going home I said drop by my hotel room and I??ll show you how to process it in TBC. 5 minutes, drop the files in there, complete report, error ellipses, etc. Linework too.
I went out with another crew. They worked together and I worked by myself. 2 days of Topo. TS & RTK. The night before going home I said drop by my hotel room and I??ll show you how to process it in TBC. 5 minutes, drop the files in there, complete report, error ellipses, etc. Linework too.
No kidding, it is ultra fast when you have good field procedures.
I've always found that the problems only start when the processor doesn't understand the TBC computation engine and/or doesn't understand error propagation and LSA. Throw a couple of minor field blunders in there and processing time will go from a few minutes to several hours, or sometimes I've seen folks just totally freeze up and not be able to troubleshoot the network.
No software can completely overcome ignorance or inexperience, willful or otherwise...
@beuckie?ÿ
I can't agree more with this.?ÿ
It's standard practice for us to set out control now with RTK, occupy the control with a robot and do one or at most two point traverses between control points and check in.?ÿ
The world has changed, adjusting out that .02' or the 5mm "error" is pointless for most tasks I do. If the error shows up large, then it's time to resurvey.?ÿ
For normal, standard stuff i don't get you guys still use an adjustment routine in the office.
Adjusting is not the primary reason for running data through an adjustment routine. The primary reason is to identify and eliminate blunders. Adjusting is just something that happens incidentally. Doing that on the data collector in the field has its place, but I'd prefer to do it in the office on the big screen.?ÿ?ÿ
Few of my control surveys are of the loop type. But all have redundant measurements on everything. If I don't adjust I'm using one measurement to determine a coordinate, and treating subsequent measurements as mere checks. But they aren't simply checks, they are as valid as the first measurement. I prefer to take advantage of all the (correct) data I've worked to collect to determine a final coordinate.?ÿ The adjusted difference?ÿ is rarely worth the effort, but the elimination of blunders always is.?ÿ ?ÿ?ÿ
Paraphrasing Jan Van Sickle from a presentation at a recent conference...all measurements contain error, and therefore proper procedure is to adjust them. Random errors can and should be properly distributed.
It's far more common now to mix observations of varying type and quality. An RTK vector is not the same thing as a total station observation, which is not the same thing as a level observation or a post-processed vector. Any of the above can vary in quality and thus, how they should be used relative to other observations.
Treating them all as equivalent simply because they came up with approximately the same coordinates or heights/elevations is to make a fundamental mistake. This is especially critical when attempting to sniff out blunders and outliers - or when trying to build a reliable, repeatable network.
We do small records of survey and short plats, which are pretty simple and have looser tolerances. We do topographic surveys ranging from a single lot up to a section or more, which can be more complicated and have moderate tolerances. We set targets for manned and unmanned aerial surveys and static and mobile LiDAR - need pretty good coordinates there. We create, maintain, and use tight control for precision construction staking on heavy civil projects. We set geodetic control for large-scale projects like 50+ mile transportation corridors and wind farms. We occasionally do control networks for deformation monitoring, and sometimes the monitoring itself.
All of that work contains random error, and can easily be evaluated for blunders and outliers. Every project gets at minimum the same best-practices treatment for quality control, analysis & adjustment. As @norman-oklahoma mentioned, the primary reason is to identify and eliminate blunders, and sometimes outliers. But once you're done, you have updated coordinates that are the best possible values. Why toss them aside?
I'm not hearing any valid reasons against employing best practices, when the software makes it so easy and it takes minimal time.
for me personally, I wish somebody could actually post up how they use Civil 3D and the .fbk files from a data collector to properly do a least squares adjustment using C3D. I have added the report style generator to my data collector running trimble access, exported the .fbk file and imported it in C3D through the survey database portion. But I have not been able to figure out much from there myself though I do occasionally see others swear they've used it successfully many time. I know the data collector itself will perform simple adjustments on traverses but being able to perform a LSA, analyzing the data and reporting about it without purchasing TBC, Starnet or Carlson would be nice. Just wish Autodesk would address the need somehow
For those people who run a loop traverse and close it out to find a linear and angular misclosure that is well within their acceptance level for error (then adjust or not based on their determination of the need), what does LSA bring to the table?
To me, in the case of a traditional old fashioned closed loop traverse (without cross ties, solar azimuths along some lines, GPS observations here and there or some form of redundancy other than the closing line), there seems to be too little redundancy for meaningful least squares analysis.
What am I missing in this scenario?
For those people who run a loop traverse .... what does LSA bring to the table?
Freedom from having to dogmatically do loop traverses to get some sort of analyzable redundancy into your work.
a traditional old fashioned closed loop traverse (without cross ties, solar azimuths along some lines, GPS observations here and there or some form of redundancy other than the closing line)
I can count on one hand the number of times I have run or processed one of those in the past five years. Maybe two hands will get me to ten years.
But even if that's all I had, I would still use LSA because all else being equal, it is best practices and returns the best results.
https://www.xyht.com/gnsslocation-tech/i-dont-need-no-stinkin-statistics/
@beuckie So you can check from point to point and make a decision if its to large of an error. But what about how one point fits to another all the way across a site or from one property corner to another thats not visible from same set up etc. I agree a lot can be done and checked in the field especially with someone like your self that has time under the belt. But something to be said also for having another set of eyes check your work. If I do calcs and I stake it and no one else checks it its only my perspective. I would rather someone else do the calcs let me check or vice versa same with control. If i do the field work I ask someone else to run it through the ringer or at-least do a look over .
@beuckie So you can check from point to point and make a decision if its to large of an error. But what about how one point fits to another all the way across a site or from one property corner to another thats not visible from same set up etc. I agree a lot can be done and checked in the field especially with someone like your self that has time under the belt. But something to be said also for having another set of eyes check your work. If I do calcs and I stake it and no one else checks it its only my perspective. I would rather someone else do the calcs let me check or vice versa same with control. If i do the field work I ask someone else to run it through the ringer or at-least do a look over .
I must tell that the area we work in is completely covered with a rtk network we can login too. This means that all setups i do and most surveyors over here are resections between 2 or more (i use 4) gps'd points.?ÿ
A traverse with tribachs and all the needed stuff isn't done anymore only at critical stuff like railroads. I used to traverse and use least squares in the beginning until like 5 years ago.
My field software gives the errors from my setups. I can check all in the field for standard topos.
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For construction i use the ts of course and set out multiple points and resect them from more free setups to have optimal accuracy.
For normal, standard stuff i don't get you guys still use an adjustment routine in the office.
Adjusting is not the primary reason for running data through an adjustment routine. The primary reason is to identify and eliminate blunders. Adjusting is just something that happens incidentally. Doing that on the data collector in the field has its place, but I'd prefer to do it in the office on the big screen.?ÿ?ÿ
Few of my control surveys are of the loop type. But all have redundant measurements on everything. If I don't adjust I'm using one measurement to determine a coordinate, and treating subsequent measurements as mere checks. But they aren't simply checks, they are as valid as the first measurement. I prefer to take advantage of all the (correct) data I've worked to collect to determine a final coordinate.?ÿ The adjusted difference?ÿ is rarely worth the effort, but the elimination of blunders always is.?ÿ ?ÿ?ÿ
When i started out we would measure and code but couldn't check setups until in office. Of course checking was needed then but with continuous evolution of field software and the use of hybrid setups with a 100% coverage of rtk we don't need to have the procedures like before.
It depends on the task at hand of course but measuring a light pole with an offset will give different results everytime you remeasure it no matter how much control you do on the setups.
But that's my workflow of course. Everyone does it at their best thoughts.
For those people who run a loop traverse .... what does LSA bring to the table?
Compass rule is a 2d function in a 3d world. LS will also handle the blunder detection and adjustment of elevations.?ÿ