If you are locating all the controlling corners by RTK then I don't see the need to use a Total Station on RTK control to set a monument.
That always did seem silly to me but I assumed that was because I didn't know better.?ÿ heh?ÿ Glad to see someone else throw that observation out there.
Much easier to measure an existing mark precisely with GNSS (static or RTK) but not so easy to set out to the same level of precision in a time efficient manner. Setout, measure, iterate.. takes a fair bit of time or you rely on the instantaneous RTK positions abs accept lower precision.
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Total station same precision whether you are fixing existing or setting out.
I'm surprised at the hesitancy to use RTK to stake boundary monuments. When done with care RTK can be an extremely efficient way to stake points in a variety of conditions.?ÿ
For those who require return trips under different constellations, have you found occasions when the second trip detected an outlier? If so, were the outliers obviously bad fixes or were the outliers just loose precision that exceeded your staking tolerance?
As was mentioned about Trimble, the ability to divide the abundance of constellations now allows users to work under different satellite geometries in real-time. For the past couple of years Javad's latest receivers have engines that run in parallel and each use different groups of satellite signals in each engine. This means that generally when two or more engines fix, the likelihood that the fix is good is extremely high. No waiting required because each engine is using a different geometry of signals. It's an incredibly robust strategy for verifying the solution is good in a very short amount of time.
I've been staking with RTK for years now, even before Galileo and Beidou were added. With good procedures I've never found a stake out of tolerance. I might find one someday, but to-date I've had great success. But there are rules.
When in canopy, I use the instantaneous position to roughly navigate to the stake position, then use the collection routine to improve precision (by averaging) and improve accuracy (by repeating the fixed solution). This is done automatically, so I simply wait and let it cook. Once I'm fairly certain of the accuracy (i.e. good fix) I make adjustments to my position, then repeat the process. Once I get to my coordinate, I set the point, then stake to the point one last time, storing this coordinate for my "as-set" position. Typically I'll have to get at least 4 verified positions while staking: first, rough position within 3-10 feet, adjust position, second, rough position within a foot, adjust position, third, fairly close position within a tenth or two, adjust position and set the stake, fourth final position (if within tolerance) and store point. This isn't any different than staking with a total station which probably requires at least four shots to stake a point. The difference is that getting 4 verified positions in canopy with RTK can obviously take longer than 4 shots with a total station, if the total station is already setup and looking at the target point.?ÿ
With older GPS-only or GPS+Glonass-only RTK, the process can be quite slow in canopy. Is it slower than finding a nearby clearing, setting two or three points, humping in the total station, tripod, and poles to set the point by total station? That depends on a lot of specific factors to the job at hand. Small sites will tend to favor total station stake-out over RTK regarding efficiency and accuracy. Large sites will tend to favor RTK for efficiency and accuracy.
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I don't get it either, RTK has upped the accuracy of field surveys considerably. As time goes on I'm following so many older RTK surveys and it's a matter of checking against the record.
The most recent boundary for a subdivision I returned all record information for the plat. Sure there is a few hundredths floating around in the 1/4 section between new locations and record but,,,,,,,,pftttt.?ÿ
The most annoying thing is to be sure lines don't get attached to a coordinate .02' from the record using a check shot. Some of the points have half a dozen locations from surveys over the years all clouded around the original RTK location.
And this is repeated and repeated all over our surveying area.?ÿ
It's revolutionized surveying.?ÿ
We normally haven't done tight control for construction or pushed really deep into canopy using RTK, but even that's changing.?ÿ
As far as good procedures it's still about first principles like surveying has always been. CHECK, CHECK, CHECK.
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We have used similar procedures for well over a decade, setting hundreds of monuments. We have relocated dozens of them over the years and never found a problem. I can't understand the hesitancy, but as Moe says, CHECK, CHECK, CHECK.
Won't do anything for real world positional accuracy, but it will make your points look pretty for relative accuracy in case someone starts checking them with a total station.
. CHECK, CHECK, CHECK.
Javad has automated this. Virtually eliminated all bad inits. Unless you override and quit before it's done. Even then, you can press "resume". It will continue until it's conditions are met. You can configure these, as needed.
I don't work for javad.
They work for me.
Nate
We use the same RTK procedures to set corners as we do when we tie them.?ÿ
Tying corners with RTK:
- First tie of corner, say at 815 am. Set stake alongside, perform any maintenance needed.
- Wait 15 minutes. Take field notes, catch up on email or texts, shoot the breeze, etc. Dump antenna at least once during this time.
- Second tie of corner. Averages for H and Z better be under a 0.10', typically we see less than 0.010'. If anything greater than 0.10', wait another 15 minutes and tie again. Rinse and repeat as needed.
Setting corners with RTK:
- Stake to corner location. Make "dimple" with rod at corner location.
- Dump rod, wait 15 minutes.
- Stake to corner location again, make second "dimple". If less than a tenth (unusual to see anything greater) set the corner. Verify staked position after physically setting the corner.
- When setting dozens to hundreds of corners for subdivisions, we do not do the "tie, dump, tie" routine, but rather go through and set all corners on day 1, then go through and verify all corners on day 2. In the 20 years of using GPS to set monuments, I have rarely found any error greater than a few hundredths using these methods.
I have tied monuments that I set 10+ years ago using these methods, from a completely different base position, and not seen any great error.?ÿ
Have confidence in your equipment, procedures, and personnel, or don't bother to do the work at all.
Mike
Quite frankly, if the location is in the open, I'll stake by RTK, record a check shot of about 30-60 seconds duration, and move on. With 14 satellites in view there is very small chance of a bad fix in such a circumstance. The location is going to be under the magic 0.04' limit. By the time I've staked the location, set the pin, checking and adjusting as necessary I've been on the point several times over a period of several minutes. Then I just need one more for the record.?ÿ?ÿ
If the location is not in the open I will set 3 well spaced random points by RTK that are in the open, each with a pair of 60-90 second observations, rotating the rod 180?ø in between. If I'm not getting good statistics in 90 seconds then it isn't an open location, is it? Then setup the gun, resect, and stake.?ÿ?ÿ
That said, working exclusively with RTK is pretty rare in this part of the world. We can usually find enough clear spots to get the control "on the grid", but there are always too many obstructions to go all in. Unless you happen to be working on an airport, or something like that. This is robot country.
Norman, did I ever tell you about that tunnel project I did exclusively with javad rtk?:)
Norman, did I ever tell you about that tunnel project I did exclusively with javad rtk?:)
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You joke, but one day.....
I've been staking with RTK for years now, even before Galileo and Beidou were added. With good procedures I've never found a stake out of tolerance. I might find one someday, but to-date I've had great success. But there are rules.
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It appear that a NEAR mountpoint gives me slightly less accurate readings, but is more reproducable month after month. Where iMax or VRS provides lower error numbers on site, but larger disagreement when returning later, it appears.?ÿ?ÿ
It appears that a NEAR mountpoint gives me slightly less accurate readings, but is more reproducible month after month. Where iMax or VRS provides lower error numbers on site, but larger disagreement when returning later, it appears.?ÿ?ÿ
That's interesting Mr. Pacer. I prefer to work with a local base. I'm not against RTNs, I just seem to get better performance from my own base. Multi-constellation seems to have really brought the scalar uncertainties down from GPS-only or GPS+ Glonass solutions, so the difference in performance between RTNs and local base stations will probably continue to decline, but I don't think it's become negligible yet.
I??ve read that surveyors are the only ones that worry about small distances, not the courts and not most land owners. ?ÿIf you set the corners for a lot in town and they are off 0.10?? does it hurt anything? ?ÿThat said I would not use gps to set corners in town but did for rural areas. ?ÿI??d set the corner, reinitialize the receiver and check it. ?ÿ?ÿ
@david-livingstone you're touching on the next topic I was planning to discuss: practical accuracy.?ÿ
@shawn-billings I admire your courage sir... (you realize this is likely flirting with blasphemy and banishment with the survey perfection masters here who would never publicly condone, accept or admit to having allowed error greater than the space between 2 dimples during their professional career)
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@tfdoubleyou if you use it to position the corners found. Just reverse the same procedures. If its good enough to locate one its good enough to set one. I agree in rural areas its a no brainer.?ÿ
@i-ben-havin two dimples is cured by a bigger punch lol. Now one dimple.?ÿ
Do you favor 15-minute sessions because that's the least amount of occupation time to be considered a static session? I know you're referring to them as RTK procedures. Here in central Florida, I usually get H residuals of 0.005' or less and V residuals of 0.01' or less within 2 minutes. We average 13 satellites in an open sky.
