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Best fit elevations over known or established control

  • 1.  Best fit elevations over known or established control

    Posted 08-26-2023 08:49

    Hello. I'm pretty new to adjustments in TBC. I think I have the level editor down for basic level run workflow and adjusting those runs to themselves over a starting and ending known benchmark elevation. The question is once you have a level run adjusted and newly adjusted elevations...how would you best fit those results over known or established control. For example, if you are provided several benchmarks on a site and you want to best fit your run over those values, what would be a good work flow? Say you have 5 benchmarks you want want to fit your elevations over those 5 points and produce residuals, if you enter all 5 of those points as benchmarks on your level run as benchmarks it will re-start your adjustments at each one of those benchmarks. My desired result is that it would give you residuals over those points to try and match the provided elevations best as possible.

    Hopefully I am doing a good job explaining what I am trying to accomplish. I just don't know if this a more a function for the level editor, or I need to complete my level data and then move on to a network adjustment. I am less familiar with the network adjustment routines and not sure if you can do this vertical only type of adjustment. 

    Any feedback or thoughts would be appreciated. Thanks!



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    Elijah Voigt
    Land-Tech Services LLC
    New Jersey USA
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  • 2.  RE: Best fit elevations over known or established control

    Posted 08-12-2025 11:21

    I know it's been years at this point, but did you ever get a response or resolution on this question? I have a monitoring survey that I am trying to do the same thing, but there is only one BM that can be held. 



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    Sean Lahann, PLS
    Phoenix, Arizona
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  • 3.  RE: Best fit elevations over known or established control

    Posted 08-12-2025 16:03

    Hey, I was just told this can be done in TBC. Needs to be brought into excel and manually calculated. 



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    Elijah Voigt
    Land-Tech Services LLC
    New Jersey USA
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    Original Message


  • 4.  RE: Best fit elevations over known or established control

    Posted 08-13-2025 06:10

    Ok, so then you would just hold the "computed" elevations in TBC without holding them as BMs and calculate the differences in excel? Or, just hold each level run with BMs (as TBC would suggest) and do the adjustments and then see how they compare at the end in excel? 



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    Sean Lahann, PLS
    Phoenix, Arizona
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    Original Message


  • 5.  RE: Best fit elevations over known or established control

    Posted 08-14-2025 13:02

    my workflow has been to get correct level elevations computed. this can be in tbc, or other software proprietary to the level, or manually in excel. i played around with the tbc level module and for our purposes it was way clunky and not worth the effort. excel was a more powerful solution. either way i would choose to dump the data out of tbc because i am not certain of how tbc would handle the data from the level module. others might be more confident with how tbc handles these, and it can also be tested easily if you do the steps bellow to them and note the verticals before and afterwards:

    once you have the correct elevations for the points, use the network adjustment tool in tbc. create control quality coordinates for all control points especially the ones with known horizontals and the leveled verticals. when you go to do the network adjust choose to hold the verticals on all those that have been leveled to and the horizontal on known horizontals. this will force tbc to hold those good verticals. 



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    ian bissonnette
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    Original Message


  • 6.  RE: Best fit elevations over known or established control

    Posted 08-18-2025 11:24

    Hi Sean,

    I have had success importing the level data into TBC from an excel template. I attached a copy of what we use.  I just let the raw data be and incorporate it into the network adjustment. I then review my least squares network adjustment report for the entire network to be sure it is holding the level data as the highest quality for the vertical.  I will hold the primary control point on the project fixed. You have to adjust the standard error in the level editor for each run.  In project settings specify that the standard errors are coming from the level editor vs. the project settings. This has worked well unless you have funky level data that is not closed loops and such.



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    Rob Goodwin
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    Attachment(s)

    csv
    LevelData Template - TBC.csv   83 B 1 version
    csv
    LevelData Example.csv   631 B 1 version
    Original Message


  • 7.  RE: Best fit elevations over known or established control

    Posted 08-28-2025 09:06

    Rob, 

    Thanks for the info and the files. I will give them a try. 



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    Sean Lahann, PLS
    Phoenix, Arizona
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    Original Message