Yswami:
For example...I setup on 200, BS 100, and FS 300. Then shoot a bunch of topo. I decide to check the BS, I call it 100. Or if I take another shot to the FS, I call it 300. Then i traverse around, and come back to 200. I call it 200. My angle check there would be to either 100 or 300 (or both), and they would be stored as such.
Here is an example from a project we did last year (which I posted about previously). The first image shows all of the traverse points. All of these points start with 13076, then two letters, for example 13076CC (13076 is the job number). The map also shows VH-0? points, they are actually 13076 with a single letter, as that was the primary traverse, but the designation was changed on the map to VH-0? to show them differently. So, anytime I came back to a junction point, it got the same name as before. If my traverse came back in to a previous point, I immediately see the misclosure (in position and elevation) on the screen. I do not see an angular misclosure that many are used to seeing, but I don't care about that. I was more concerned with the vertical misclosure of the traverse, as that was more critical.
Then, I shot around 7000 total station (green) and RTK (red) topo shots.
These points were numbered as 4 numeric digits (total station) or a letter and 4 digits for the RTK because we were running two rovers at the same time, so the letter for the RTK represented who the operator was, for example J0905 and T1134.
All of this raw data was downloaded and put into a database where corrections were applied. Then it was easy to export just the traverse data by selecting 13076* and running a least squares adjustment on that data only. After that was done, I used the adjusted coordinates to compute all of the topo shots, by specifying ranges to be computed (0001-9999, J0001-J9999, etc). No sense in trying to adjust the topo data, as it is all radial.
Hope that explains it
Another situation that happens a lot is we do deformation surveys year after year on the same points. I load all the adjusted coordinates from the previous survey into the data collector. When we are setup, that makes pointing to each point to be surveyed real easy, and I set the tolerance to 0.000 so that it always displays a misclosure. Then I "store another" in trimble speak. We do not need real time closures or coordinates except when doing a dewatering survey. That is when we have to shoot a bunch of points on lock walls every hour for 24+ hours during drawdown to make sure the wall is not moving. In that case we are concerned about the real time values, so we do an initial survey before pumping starts, and then compare each observed coordinate set to the initial values. We strive for 0.003 m accuracy, the "alarm" criteria is 0.006 m.
As for downloading coordinates versus raw data, we usually have a lot of redundant data on the main points, and we often mix GPS with total station and also leveling. So, using raw data (processed to mark-to-mark values), I can combine static GPS, RTK, total station, and leveling in a single adjustment and get a good homogenous network. I have done that for other companies as well when they have a complex network, basically taking their data and processing it all together to get the most consistent set of coordinates.
Once I have adjusted coordinates, I can use the raw topo shots (angle, distance and vertical angle) to compute topo coordinates. That is pretty straightforward, just simple trig calcs.
By putting all the raw data into a database, i can easily correct things like bad HI or HT, make sure all the weather data is correct (Temperature and Pressure), and make sure the prism constant(s) are all correct before doing computations.
Aloha,
Thank you so much John. That was a very helpful examples.
I remember seing your post in the past. At that time it was way over my head. Looking the images with your explanation, I can follow what you've accomplished.
7000 points...now that left a strong impression in me! It might take me a lifetime to do that many within the monastery boundary! B-)
It was a very tough site...thick underbrush, briars (what we call jaggerz in western PA), and many many piles of slag (large and small) dumped all over the site, as well as some very large holes. Fortunately we did it in late fall. Not sure what really went on there in the past, why there were so many piles and holes in there. We had to do a 1' topo of the site for volumes. Not to measure how much was there, but to use as a base for what is going to be dumped there in the future...dredgings from the Lower Mon project. Check out the video of the wall demolition on that page. We used to monitor that wall for movement, every time we went out there it was leaning more precariously. We were there yesterday finishing the installation of monitoring pins on the new river wall.
Of course it was a "hurry up and finish" project. They needed the data for contract documents. It would have been so much easier if they had waited until the site was cleared of trees. I flew over it last weekend-nothing has been done there at all, 7 months after our survey.
Aloha, John: I am not a big fan of explosive stuff. But that was a cool video!
