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Trimble Access, how to assign elevation to previous shots
Posted by sarkiss on July 7, 2023 at 3:04 amI setup instrument on point “A”, enter height, do the setup, start topo shots with rod height, then at the end I forget to take a shot to my BM. I move to point “B” which of course has no elevation, then do the setup with backsight as “A”, Now i take a shot to BM and all my points from now on have elevations, INCLUDING point “A”, is there anyway to manipulate the job file ( on the data collector, or later on PC) so that all the previous shots taken from Station “A” get their elevations based on BM?
OleManRiver replied 1 year ago 7 Members · 15 Replies -
15 Replies
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There are a couple of possibilities here…
On the Cogo menu there is an Adjust option
Under that you have Fix Station Setup or Transformations amongst a couple of others
With Fix Setup you can translate the station – in your case add in the height – and all the points from there should be adjusted. You will need to do station B separately from A
With Transformations you can apply a transformation to a group of points (usually a point range). Work out what the adjustment you need is, and apply to your points – you can do them all in one go if it is the same for station B as A.
Take a look at the Help for details
Strongly recommend you make a backup copy of your job before you start
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I setup instrument on point “A”, enter height, do the setup, start topo shots with rod height, then at the end I forget to take a shot to my BM. I move to point “B” which of course has no elevation, then do the setup with backsight as “A”, Now i take a shot to BM and all my points from now on have elevations, INCLUDING point “A”, is there anyway to manipulate the job file ( on the data collector, or later on PC) so that all the previous shots taken from Station “A” get their elevations based on BM?
It’s one thing to forget to shoot the BM at the beginning (or even at the end) of the setup, but if it doesn’t get shot at all it’s not exactly a typical routine for (any) field software to “back in” elevations of one station, based on a subsequent shot from a totally different station, that got its own elevation from the BM.
If the BM had been shot and a Station Elevation routine not performed, it’s definitely possible to just look at the deltas between the observed and published BM elevation in the Point Manager, and then modify the station “A” elevation by that amount. In theory you could extrapolate that routine out to the second setup where the BM was observed (would be easier if there were a Station Elevation routine run at the station on “B”), but it’s messy.
I’d be looking at simply processing in TBC by constraining the elevation of the BM in a network adjustment. That will bump everything to the correct vertical without having to manually compute deltas and modify grid point values. As long as your data are all tied together, and you have one or more observations on the BM, this method is fastest and easiest.
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman -
Some clarification, I usually don’t forget to tie to the BM for a topo, this was a survey to locate the building on a property. As you might guess, I didn’t need the elevations, I just add that info in case I need it. I have not worked on TBC and not familiar with it, if the process is not time demanding I will try it, otherwise I thought a manual change in the job file on TSC5 would solve the issue.
At this time this is not an urgent matter, but I thought I ask for advice in this forum in case I need the knowledge in the future.
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Kinda sorta not really related question but this thread is close enough…
If I do a vertical offset in Access (I assume it works the same for GPS and robot but if it doesn’t then let’s say I’m talking about GPS) does the offset actually change the elevation that is recorded for the point? The reason I ask is because I was discussing this with a coworker and he thought it only modifies the linework associated with the point and doesn’t alter the point itself at all.
It seemed kind of ridiculous if it worked that way but hey, that’s why I’m asking. Also, we’re working with Access/TBC and Civil 3D here so it’s also possible Trimble treats it one way and Autodesk another.
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Thanks to the tech support from CSDS the issue is resolved. It was as easy as going into ” point manager” find the station point and edit the coordinates ( in my case adding elevation), now all previous points taken from that station have elevations.
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@bstrand to make sure i am understanding correctly. You go out with a rtk unit and observe say top of a manhole and your rod hight is 2m to bottom of quick release. But you had dipped the manhole (measured down x feet to flo line of 18” rcp). You apply the vertical offset of x distance. So rod is ag 2m vertical offset is x distance down. Your elevation will be to that point. I have not used the vertical offset much I usually just modify my rod height or rtk height. I have used the description fields and typed the invert as a test using the correct sign so i have top of manhole and distance down. I the. In tbc use smart text and do the math to label the invert elevation. And still have the top of manhole elevation. I believe Rover83 could give a better answer but i would like to say what i would like is if i do the vertical offset it records both elevation the top and the invert and tbc be able to read that . Now that could get complicated another example. I take a shot on top of a wall and for whatever reason I only want the bottom of wall elevation. One point is all needed. I could keep going several different examples of why you would use the vertical offset method. Same for robot or total station. Maybe you need a distance offset with a totally station to say a top of bank so the gun or i man can’t get you a shot so you walk directly to the gun adding the distance is easy. But you need the elevation. So yank out your hand level cut a stick tie a piece of flagging on it measure up then go to where your rod is get pocket rod and at the ground you align the hand level to see the flagging at top of bank read the tape pocket rod measurement do the math to get the vertical difference. In this case you can’t just change your rod height its not a vertical angle of 90 and the gun shoots a slope distance. So vertical offset is best. It’s triangle’s with total station and or robot. I had a topo and was looking at my data and note’s when I first came back into this side i had topo an area and had not changed my rod height. I knew what they were for a group of shots because i was down slope of the gun. The cad guy in civil 3d simply did a vertical shift of the difference in what the rod height was entered and what i told him it should have been. So he changed the elevation by x. That doesn’t work unless the va is close to 90 and distance depending as well. I went in to tbc fixed my blunder correctly. He had never computed elevation from vt angle slope distance and hi and rod hts. So he didn’t know he assumed. Now once you do some comps at different angles and distance you will get a feel for that. This was a case it made a difference that was not acceptable. Always go back to raw data TBC makes this very easy in multiple ways. Hope this makes since
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Interesting idea but I guess multiple elevations for 1 point would make some things we’re used to extremely complex.
What elevation do you want for your surfaces.working with notes or attributes and smart texts looks already a nice solution.
Not sure if CAD still has problems with 2 points/lines exactly on top of each other with different elevations.
Christof.
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I setup instrument on point “A”, enter height, do the setup, start topo shots with rod height, then at the end I forget to take a shot to my BM. I move to point “B” which of course has no elevation, then do the setup with backsight as “A”, Now i take a shot to BM and all my points from now on have elevations, INCLUDING point “A”, is there anyway to manipulate the job file ( on the data collector, or later on PC) so that all the previous shots taken from Station “A” get their elevations based on BM?
The fix station setup function would be able to fix up the data if everything originates from 1 point with E,N,Z(optionally) and a backsight created by keying in a bearing (not keying in a separate point and backsighting that point). So it would be key in A backsight B and set 0 etc, then do the pick-up and when moving to B you can backsight B. If you carry heights you are effectively calculating the difference between the assumed level/position and then applying a correction to the original coordinate A and a swing to the original backsight bearing to adjust the whole set of data.
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I used to change the rod height but that’s a recipe for rod busts, and if you field book your rod changes that just eats up unnecessary time… assuming the vertical offset works the way I assumed it did.
Anyway, I don’t use it terribly often– typically for culverts that are partially filled with dirt.
As far as storing 2 points, it might already do that actually. I’ve noticed when I do horizontal offsets there’s a uniquely coded point in the point list in TBC that I didn’t enter anywhere… so I assume this is similar to how Leica generated the hidden point when you offset things. But yeah I’d be fine with a pair of points, one where the rod is and one where the offset is.
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If I do a vertical offset in Access (I assume it works the same for GPS and robot but if it doesn’t then let’s say I’m talking about GPS) does the offset actually change the elevation that is recorded for the point?
It does indeed change the point elevation.
The vertical offset can be changed in TBC during post-processing as well (just like the distance offsets for a total station observation):
As far as storing 2 points, it might already do that actually. I’ve noticed when I do horizontal offsets there’s a uniquely coded point in the point list in TBC that I didn’t enter anywhere… so I assume this is similar to how Leica generated the hidden point when you offset things. But yeah I’d be fine with a pair of points, one where the rod is and one where the offset is.
It depends on the routine. Certain computations require a point to start from/draw from. The rectangle command is a good example – if you provide three points, it needs a fourth to finish out that figure, so an AUT1 point is generated when feature codes are processed. If you provide only two points plus a width, there are two AUT points generated for the other side.
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman -
@bstrand Yeah i have not dealt a lot in access doing these things. I remember carlson years ago sometimes had a hiccup for like offsets. Sometimes it would apply the offset not just for said shot but it would continue on after so edited the raw file back then. Yes if you have to record in the field book every rod height change the offset would be preferred. I can remember running total station and writing down everything hz angle va angle slope distance rod height and code. I use to get overtime after a day in the field entering all the info into the system. We did learn little tricks to minimize back then as well.
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@christ-lambrecht yeah well i am not a cad guru. But i am tweaking my code library and i can do that after the fact as well to use in surface or not for TBC. Much can be automated by the code. So Ground shots toes tops all in surface automatically. Inverts bldg corners signs power poles utility markings not included in my surface. Now they all usually still have elevations on them. Besides the inverts this actually makes for a great contour check as well. Because i can have those points not used in surface but check elevation against the surface or contours . Terramodel i could use a code in the field to dictate that and even what type of breakline i wanted so much was driven from the field. Cad civil 3d it seems you group points to add to the surface. I have very little knowledge of that though.
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