Why do you think the people that
The newer total stations with the right procedures are every bit as good as the old t-2 and tape. GPS cannot perform to the same level.
Reminds me of guys who used to occasionally run a traverse that closed better than 1:100,000 and proclaim "We did First Order Work!". They had no idea what the actual limitations of the 1' theodolite with the top mount Red-1 they used to get there were, and no idea that getting such results was at least as much luck as it was careful measuring.
If the builder only needs a couple of stakes +/- 0.1', I guess it's OK. But most builders I've worked with want far more accurate stakes than that.
On a .25 acre lot I could use a total station and bi pod and probably do it just as quick if not quicker than a gps.
It makes me wonder about the education, experience and mentoring of the OP.
Wow!
You really got the flame going.
We use "GPS" in all sorts of conditions. We want to make it work. I have lots of old farts in the office that don't trust it. I don't trust it a lot of the time.
That said, sure you can stake a house with GPS. Do you really care if the house is in the wrong position by 0.06'? Anchor bolts...I wouldn't, but that isn't the question. Say you set four corners plus a baseline on one side. If you cross check your points, and they are within tolerances, you are good. (And make that check to the property line.) If you want some redundancy, break lock, and get a new initialization, and recheck the points.
Yes, waiting half a day and rechecking would be better, but lets be real about what is really happening.
And...no I don't use GPS for house staking. I think a total station is just as fast, and it makes the old farts signing things happier. If it is under a person's license, I do it how they want.
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> "...Since 2002, NGS has been providing the GPS community with OPUS processing, free of charge. Among the limitations for using OPUS, the time duration of the GPS data set was always emphasized. A minimum of 2 h of data is recommended to obtain results sufficiently accurate for surveying applications...
I apologize for my immediate and necessary (due to a character flaw:angel: ) sarcasm:
[sarcasm]Are you using OPUS to stake things? Even with RS, I can't imagine that being very efficient. [/sarcasm]
The original poster is talking about RTK, which is a different beast. OPUS's solutions are fine for somethings, but with RTK he most likely has a vector from a base-station sitting on a control point a couple of hundred feet away, looking at what is essentially the exact same sky. Overall accuracy (geodetic) is irrelevant in this particular case, while accuracy relative to the local control is relevant.
GPS can tell you where you are, but never how good it is. If you never need to prove how good it is, all you need is a GPS. If you need a high-precision local fit, GPS will not do it.
Optics & EDMs tell you how good it is in terms of absolute differences but are not so efficient at carting coordinates over a long haul. So they never tell you Where quite like a GPS.
Least squares is where you combine the GPS "maybe heres" with the terrestrial "how goods" to get your "this good right here" results. But that'd be overkill for building corners. Expensive skyscrapers, maybe.
GPS gives you an error ellipse, but bear in mind that with RTK, the point quality is only a prediction. It may SAY you are good to a few hundredths but you won't really KNOW until you break out the total station, or at least a tape.
You would need 24h post-processed static on each corner to square it like you could with a builder's transit. Kinda cumbersome.
If you are setting forms with RTK and not hearing about it, there is probably an experienced carpenter on site blessing it after you leave.
> GPS can tell you where you are, but never how good it is. If you never need to prove how good it is, all you need is a GPS. If you need a high-precision local fit, GPS will not do it.
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> Optics & EDMs tell you how good it is in terms of absolute differences but are not so efficient at carting coordinates over a long haul. So they never tell you Where quite like a GPS.
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I think that this is a pretty good description, and so if I set a foundation with GPS, I would pull the diagonal and the between all points, and make sure that they match - ON THE GROUND - to within my tolerances.
But, I would do that with my total station if I wanted to make sure I was right. See, there are things with total stations that can cause errors. Just trusting the black box with a total station can cause a lot of pain too.
If you set say 6 points with GPS, and then they all match each other, (especially if you forced your equipment into a new initialization at some point in there)the chances of you being in the wrong spot by more than something bigger than [no one cares] is very small.
I doubt the average slap-em up home builder's $10 an hour framers would notice an inch or even 2 inches in length or squareness.
You could set all of the corners with RTK (assuming good PDOPs) then wait until 4 hours after the start of staking, reinitialize then check them all (get redundant vectors) then process it all in least squares to get an idea of the true accuracies.