Haha! Finally someone else who calls a Total Station a Jigger! It's good to see another Aussie in here.
Elk,
Personally, I resect everything. Occupying a point and setting a backsight from another point just doesn't give you enough redundancy. In fact, it doesn't give you any. If either one of those two points has moved (or both) then it's entirely possible that you might not notice the error. What if, by some miracle, the point you occupy has moved 10mm east and the backsight has moved 10mm west? The only way to check such a scenario would be to perform a check from/to yet another known point. In that case, you are taking as long as you would to perform a resection anyway. So what's the point? A resection/least squares solution is the only method I ever use. Even to traverse.
Scenario 1: You show up on site. Assuming no-one has parked their Mum's Toyota over your known point; you set up over your mark. Level up and centre your instrument etc......that all takes time. Then, assuming that no-one is blocking your view of your check sight; you take a shot to it. But is that enough? I would suggest not. Is your colleague actually reading a distance to the check sight? Or is he only turning an angle to it then setting a bearing? If it's the former, then he needs to perform more checks. If it's the latter, then he doesn't need to anything other than stay the hell home.
Scenario 2: You set up wherever you have clear lines of sight to your stations and the work area. Ignore the Toyota. Then you only need to level your instrument. That's it. A resection/least squares solution to 3 or more points allows you to see your scale factor result as well as the positional vectors of every station you just took shots to. Don't like one of the positional vectors? Delete it. Not happy with your scale factor result? Deleting the point with the highest vector fixes that problem too. Then watch your solution tighten up. And, if you're reading tape targets, the entire process is a whole bunch faster than occupying a point. Getting regular bad positional vector results in your least squares solution to one particular? Then re-record it or destroy it.
To be honest, and to add my two cents' worth, I think more needs to read into what John said regarding "control budget". It's a difficult thing to justify to a client who 99 times out of 100 doesn't understand the concept and only sees it as yet another expense. However, you sound like you are under pressure to perform as quickly as possible in a zoo. Perhaps your gripe should be directed up the chain of command as well as down (and here of course!) If you haven't been given the opportunity to install quality control in the first place and then be given the opportunity to maintain it then I would suggest that this entire site problem you have is irrelevant. Personally, I have been known to stay back after the clock has stopped running to tidy up my own control. I'm pretty anal about my control. (I had to re-read that sentence twice to make sure I didn't get my adjective and noun backwards.)
I also agree with Nate. You need a thick skin around here. But don't forget: more than half of all communication is via body language. We don't have that luxury here.
Mick.
We had a meeting this morning. All of the Party Chiefs and our immediate supervisor.
Resections are no longer allowed.
For all of these reasons outlined in the posts above, I'm pissed. A valuable tool is no longer available in my tool kit.
The irony is - to me - that we are required to traverse with set collections that have less than six minutes of error. Which is fine. It's good to keep things tight. But when we do a setup to shoot Topographic shots, we just occupy and backsight with no required forsight check!
:fever:
I love resections. I always use at least 3 points. I use them most of the time.
voidintheabyss, post: 426411, member: 11972 wrote: we are required to traverse with set collections that have less than six minutes of error.
That's an enormous tolerance value. Are you sure they don't mean six seconds?
voidintheabyss, post: 426411, member: 11972 wrote: We had a meeting this morning. All of the Party Chiefs and our immediate supervisor.
Resections are no longer allowed.
For all of these reasons outlined in the posts above, I'm pissed. A valuable tool is no longer available in my tool kit.
The irony is - to me - that we are required to traverse with set collections that have less than six minutes of error. Which is fine. It's good to keep things tight. But when we do a setup to shoot Topographic shots, we just occupy and backsight with no required forsight check!
:fever:
It would be resume time for me, micro managing competent field crews isn't ever a good idea. Why make a field guys life any harder than it already is?
Don't resection, free-station...
elkboarder, post: 421679, member: 12485 wrote: Hi everyone. I am currently having a little bit of an argument with one of our more experienced field crew members. He's been surveying for 15+ years and in my opinion has some bad habits that he refuses to unlearn. One of these is his firm belief that resections should and I quote "only be done when there are no other options" We are currently working a very very busy construction site with more equipment and machines blocking our line of site than I can describe. This just so happens to be our busiest part of the project, we are both crew chiefs however I am the lead in this project. He is very stubborn and more than likely upset that a 30 year old is trying to tell him how to do his job. I normally would not tell anyone how to do their job as long as they were not screwing anything up however his method of setting on the same two points repeatedly and setting points off this setup if something is in his line of site is starting to just get silly and I believe he is introducing more error into what he is laying out than needed. Behind the project is a large ridge that we have control on (traversed control.) For the past two months I set two backsites on whichever points will give me the best angle and then run my resection and lay out whatever it is I'm laying out. 90% of my layout work is foundations and anchor bolts. I do this for many reasons and will list them. I would just like anyone's input on if any of my theories are flawed because I'm trying to really figure out why he's so against them.
1. With resections you can set up right next to what you're laying out
2. You are establishing control while at the same time setting up for your layout, saving time.
3. With you being so close to what you're laying out the error decreases. When I stake out my backsite which is 900' away after an hour and see an error of .04' I know that that error is much less on what I'm laying out because of how close I am.
4. Easier to re-level the transit when it's sitting 20' away from you.
5. Resections help to average out error in setups.
6. We get a lot of different tasks throughout the day usually I lay out a foundation with 40 anchor bolts in about an hour and then get a call to do the same thing 150' away from where I'm at. This allows me to pick up by transit, move to where I need to be, turn the glass on my backsites if need be and run a new resection.With all of these advantages I just don't understand his thinking. I do (and not bragging here) but at least double the work he does throughout the day because of this method and it's actually starting to make me mad because part of me thinks he's doing it on purpose so he doesn't have to work as much. Half his day is figuring out control dilemmas where I never have that problem. The way this site is setup is we have a fixed GPS base and are running a local coordinate system. The GPS is calibrated to our traverse so everything jives well. Whenever I stake out one of my control points of something I've laid out from a resection it always hits tight. I guess I'm just looking for others opinions on this issue and to hopefully gain a little insight on why he may be so against them.
Thanks
I love resections for topo work, set HI to 0 and all error is in the rod, working robotics it makes sense to me. I've had a similar disagreement regarding traversing as you, in my mind you are twisting the geometry not correcting it, just kind of moving along, suppose the method used would ultimately come down to the accuracy requirements of your project.
voidintheabyss, post: 426411, member: 11972 wrote: We had a meeting this morning. All of the Party Chiefs and our immediate supervisor.
Resections are no longer allowed.
I would imagine, hope, trust, that any progressive survey crew would or should be entitled to the full gamut of options available within the scope of available instruments.
I'd want my crews (assuming I had some) to learn and grasp and master the options available, including resection.
That would include an understanding of the consequences of sloppy control which would still give room for errors which ever way is adopted, what to accept and what to question or throw out.
I remember when Field Genius was being touted, and having an interesting conversation with the author before its release.
Afterwards I discovered one couldn't site to a distant reference Trig station (for egs) and read an included angle and distance to a very near point say 2 metres away.
They'd deliberately not included the option to avoid 'idiotic mistakes'.
I struggled with that as there's plenty of room to make idiotic mistakes anyway and let's educate the masses if needed and give us software that can be enjoyed in all its fullness.
Probably tread on some toes here, but I would hope any boss would want the best from their crew even if it takes effort to allow them the privilege of learning and enhancing their skills and making life easier and efficient all round.
What's taught in institutions? Do surveyors anywhere (including here) get basic training in all common applications and methods.
That's not a criticism, more a question, as I'm in the dark for our own training.
Sometimes I wonder.
I feel for those that are shackled by ways attributed only to a preference and not having options.
Life as a surveyor deserves more than that.
Richard, post: 426446, member: 833 wrote:
I remember when Field Genius was being touted, and having an interesting conversation with the author before its release.
Afterwards I discovered one couldn't site to a distant reference Trig station (for egs) and read an included angle and distance to a very near point say 2 metres away.
They'd deliberately not included the option to avoid 'idiotic mistakes'.
I struggled with that as there's plenty of room to make idiotic mistakes anyway and let's educate the masses if needed and give us software that can be enjoyed in all its fullness.
Interesting - Trimble Access includes that specific arrangement as a special case in resection.
Jim Frame, post: 426416, member: 10 wrote: That's an enormous tolerance value. Are you sure they don't mean six seconds?
Typo!
Ha. How embarrassing.
A couple weeks ago, on a site where I had resected many times before, I had a resection fail. Long story short, 4 points in resection. Select any 3, get a good value. Use all 4, get 0.12' bust. Take all data back to office and run in StarNet, no problem. So it's possible to get bogus values with good data. This happened with Survey Pro v6 on a Topcon PS.
Resections are great, but can screw up. I understand the concerns some people may have. Once bitten, twice shy.
Mark Mayer, post: 426456, member: 424 wrote: Use all 4, get 0.12' bust. Take all data back to office and run in StarNet, no problem. So it's possible to get bogus values with good data. This happened with Survey Pro v6 on a Topcon PS.
Do you mean that the coordinate calculated by Star*Net differed from the one calculated by Survey Pro, or that Survey Pro was working with a bad station coordinate in the field file? If the former, it sounds like a Survey Pro problem rather than a vulnerability in the resection procedure.
Jim Frame, post: 426460, member: 10 wrote: ...it sounds like a Survey Pro problem rather than a vulnerability in the resection procedure.
It's a Survey Pro problem. Why does that not give me any comfort?
[USER=11972]@voidintheabyss[/USER]
Not being the boss can suck some days and other days the boss is what sucks most.
One advantage of not doing resection is that it makes more work out of the truck before you can begin your routine day, so I hope the powers that be understand this.
I've had the misfortune to have worked for those that seemed to get off by having everyone to do extra steps to achieve the same goal with the expectation that they do it in much less time than was required to accomplish it their way.
It led to more mistakes and skipping steps and faking the data to spit out a number when the boss ask, and you did not get a second chance to give that number without paying a penalty.
Lucky me was a seasoned hand and it really did not affect me, the poor rookies on the crews did not stand a chance.
Unlucky boss because all he wanted a boatload of rookies he could lead down a poorly mentored path.
Was glad to soon see that place in my rear view mirror.
Last week I went to a job to set monuments and spring had sprung and the two hubs I needed to set on had backsites obscured by a new forest of green.
I found an area about the size of my truck that I could set within and see two control points and I made my resection with a resulting accuracy of 1:47683.:cool:
Good luck with your new company policy..........:8ball:
