@michigan-left I apologize I got a little off topic I was talking about site calibrations in general not just GPS however there is obviously a need somewhere or their wouldn’t be LDP’s no I don’t use GPS for layout other than staking corners for clearing or digging footers/basements was that less loosely goosey enough
I've seen other guys that won't do a resection but they will setup and backsight a point 40 meters away and shoot a point 60 meters away, then check into another control point, say it's 3cm off or 0.09ft off, and say well there is nothing I can do about it...it's close enough.
Haha. I’ve worked with people that would do that. I saw one person use a 30’ BS then set points over 100’ away. I was like
wait...you mean we're not supposed to triple the distance from the back sight through the foresight?!?!??
Also remember a guy who set two points barely 100’ apart with GPS then came back later with TS to locate a pin at least double the distance in the woods. But that was just a boundary pin so doesn’t need to be that accurate anyhow I guess ♂️
I guess anyone who would do setups like these should definitely not be doing site calibrations or resections either.
I've seen other guys that won't do a resection but they will setup and backsight a point 40 meters away and shoot a point 60 meters away, then check into another control point, say it's 3cm off or 0.09ft off, and say well there is nothing I can do about it...it's close enough.
Eh, depends on the situation. I'm ok with 0.09' in most situations, if tying into boundary. Maybe not if I'm staking out something new on a small tight lot. But on most of the work I do, I'd be thrilled with that kind of check
Yeah, I would say it definitely depends on the situation. If we're staking something right then and there, we better be resecting with tight residuals or using a backsight that is at least as long as the points we are staking out, and it better check within tolerance.
If we're doing anything that is going to be post-processed and adjusted, I don't care if a setup or two had a short backsight, as long as we turn enough sets and get enough redundancy, because it's not going to matter as much when I run a network adjustment in the office.
Back to the subject at hand, it's similar for site calibrations - we're OK with the crews doing them on the fly and running with them for short-term work, but if we have a long-term job, we will generally spend a day checking control, setting anything new, and then analyze and come up with a solution in the office that will become the master template for work.
Yeah if I'm worried about 3cm/0.09ft then it's in a subdivision with a house set close to minimum setbacks on the lot. If it's a large boundary job, tolerances aren't as tight but you're not likely doing a resection on something like that anyway. It's going to be gnss or a proper traverse.
I don't care if a setup or two had a short backsight, as long as we turn enough sets
The problem isn't just reading the angle-that may be quite accurate even without a lot of angle sets.
But you are leveraging the centering errors and if you don't recenter everything to randomize the error for every shot, or if you have a bubble a little out of adjustment that leveraged systematic error will get you.
Yep, sorry, should have been clear about that, I always do at least one relevel/recenter in between sets of angles.
I definitely prefer to crank a few more in each set with a short leg, but the centering/levelling is what will burn us.
I guess a simple setup, turn, and shoot for something like a large boundary survey wouldn’t bother me too much. Definitely wouldn’t throw another setup from that point though.
The surveyor I work under does not have a clear understanding of working with GPS or using Grid Coordinates.
O don't either. But, I've not let that stop me!!
😉
Nate
@surv3251 that is the bonus of the Bachelors vs Associates. We had to cover photogrammetry, astronomical observations, coordinate systems, error theory, GIS, Public Land System in the same class that GPS was taught in. If I did not already have a BS in Geography I would have gotten the BS in surveying.
@surv3251 that is the bonus of the Bachelors vs Associates.
Spherical Astronomy class. Said I would never use it. I was not going to work at NGS or NASA. I have a deposition this afternoon. Now when the smart ass attorney asks me if I can do this by hand, I can say yes, of course.
@surv3251 that is the bonus of the Bachelors vs Associates.
Spherical Astronomy class. Said I would never use it. I was not going to work at NGS or NASA. I have a deposition this afternoon. Now when the smart ass attorney asks me if I can do this by hand, I can say yes, of course.
Not to mention that it's a lot easier to train and mentor the next generation when you actually know and understand the technical concepts behind the things we use every single day.
@rover83 There are not enough shoulders for the young surveyor to stand on today. Thank god this forum and other media exist to fill the gap to an extent.
@surv3251 that is the bonus of the Bachelors vs Associates. We had to cover photogrammetry, astronomical observations, coordinate systems, error theory, GIS, Public Land System in the same class that GPS was taught in. If I did not already have a BS in Geography I would have gotten the BS in surveying.
@Eagle1215, you see this? Our AS at Vincennes University covers all of that. I will say that GPS was very light back in the late 90's for me but now they have their own network base station and gps equipment.