This is in no particular order, however, a good knowledge of this will be necessary, in the future, to retrace the surveys, performed by those without complete knowledge of the equipment.
1.) Failing to set a nail at the base, and resetting the base at the same location for several days. This allows them to use the same point number for the base each day, HOWEVER, they are not the same point. So, there is an offset for each day of work. One point set up was used.
2.) Failing to comprehend that the TDS software will often default to TRUE north at the base, (depending on the training of the individual) and that when they move the base, we now have a new convergence angle.
3.) Assuming that it is already on Grid. Just because it made a local projection, that was rectangular. This is a corollary of 2 above.
4.) Assuming that FIXED with the accuracy displayed is the gospel truth. In all conditions.
OK, post yours.
N
Another is to localize, holding elevations on more than 1 point. Unless you really know what you are doing, you can SKEW you projection.
N
I don't follow #1. If they don't set a durable marker on day 1, how can they set up in the same place on multiple days? Just look for a hole in the dirt!?
Set the tripod legs back in the same holes, of course!!
Number one
They don't quite understand what is going on. They think that it is no different than setting a radio antenna out... a few feet does not matter, and the software does not catch it, because it is within a few feet each time, so the lat lon is close enough to the same, to make it turn in results. But, things are not quite right.....
Number one
> They don't quite understand what is going on. They think that it is no different than setting a radio antenna out... a few feet does not matter....
Yikes...heck with the RTK, I'm concerned that anyone dumb enough to do this is allowed to drive or vote. :-O
> I don't follow #1. If they don't set a durable marker on day 1, how can they set up in the same place on multiple days? Just look for a hole in the dirt!?
I think Mr. Trump has the best response for that crew chief.
What made Num 1 come to mind, is I know a surveyor that does not set stuff at the base mark.... he re-localizes every time he goes to his job. This is plain weird. And, I retraced a surveyor that has an odd bust midway in his job, also RTK. I put 2+2 together, and figure he had problems.
Another thing that can really mess things up is if somebody moves your base nail.... So I set them at least 1" deep, to make moving it hard. Another thing that comes to mind, is Surveyors think alike. I have twice now found a nail where I wanted to set my base. AFTER I had set it. I then set a unique item at the base. CPS, RR spk, or engine push rod. Stuff that is DIFFERENT than the other surveyor used.
I can imagine 2-5 40d base nails within 20' of each other.....
N
Listening to the salesman and thinking that a FLOAT solution with an averaged error estimate of 1.00' is good enough for a wetland flag.
I was so excited in 2005 to locate flags so quickly. When they missed the TS locations by many feet, I was dismayed. Damned salesman telling me FLOAT was acceptable.
An engineer goes out and sets up his base. His task is to create a topo and design an in-channel reservoir in the middle of a gas development. All facilities for the development HAVE to be put into the company data base and a control network is laid out to do so from HARN points and bench marks.
The engineer doesn't set a point, his base is about 30' from a control point for the project, he does his topo(all ground shots), goes to the office sends his base file to OPUS does some 10000, 10000 point, designs the reservoir and sends it out to be staked by other parties. That was a fun one. Took almost all day to get his topo rotated onto the system, never did know if it was correct but the dam got built.:-(
Nate: I think some people are getting confused on your point number 1. Consider elaborating on what you mean.
I have read it, read the replies, and had to go back and re-read what you said. I can see where a different point of view would be obtained.
For experienced users, these facts are known. But for newbies and those learning and refining their techniques, this would be valuable and very useful information. This will be a good thread to pull together the vast amount of knowledge available on this board.
I have two years experience, so I am still learning how to use my TDS software and GNSS RTK system and my base & rover system. I have learned a lot on this board, and I am still learning. You are making some great points, so keep doing what you are doing, and thanks! 😀
It may be hard to believe, but Nate is right on about that: Set up a base with no monument under the antenna, and worse yet no tie to control monuments. I do it myself sometimes setting a base on the truck to keep cattle or horses from disturbing it, but then you need to set a control point nearby and tie other control also.
But some of these surveys were just ground topos, no metadata, no ties to control or corners.........makes it fun;-)
Ok, point taken
> 1.) Failing to set a nail at the base, and resetting the base at the same APPROXIMATE location for several days. This allows them to use the same point number for the base each day, HOWEVER, they are not the same point. So, there is an offset for each day of work. One point set up was used.
>
Bad surveyors are bad surveyors.
It doesn't matter which tool they use or the make of truck they drive.
They're just bad surveyors.
Not measuring your antenna height or using a fixed pole.
Here's one that had me scratching my head a couple weeks ago. Fellow goes out to set up the base on a known control point I've used many times. The job is based on DOT control, State Plane bearings, but not State Plane. He collects three known points as control and then .... shoots and stores a new point before localizing and includes it in the localization solution, accepting the results, then wonders why he's missing everything by +/- 0.5'.
> .... I do it myself sometimes setting a base on the truck to keep cattle or horses from disturbing it....
...or wildlife of the urban variety. I never thought of that. Great idea!
Setup base over point on day 1. Use FUGARWE position to collect data. Fail to collect, or collect and fail to download, static data for OPUS. Fail to check into known points.
Setup base over same point on day 2. Use new FUGARWE position to collect data. Fail to collect, or collect and fail to download, static data for OPUS. Fail to check into known points.
Repeat as necessary to complete data collection.
In the office - fail to recognize multiplicity of FUGARWE positions of base. Fail to examine for check shots. Fail to bother with OPUS positioning.
> Another is to localize, holding elevations on more than 1 point. Unless you really know what you are doing, you can SKEW you projection.
I learned about inclined planes the hard way in the early days. 5 published BM, aligned along a road fit perfect. I calibrated vertically to them and went to my site which started about 400 ft perpendicular, and then another 300 ft or so.
At the end of the day the close ones were only 1.5 ft off, the far ones were 3 ft. Bad plane, my rookie error & lesson learned.
Once I fixed it with my robot, all was good. A little bit of site re-design and it only cost me some time and shame, no money.
Calibrate to one and others are checks, or run a box around your site with a level or total station.
Fail to keep working.
