Total station data corrections

Hunter GeophysicsHunter Geophysics Global Mapper UserPosts: 75Trusted User
edited September 2014 in Technical Support
Hi Michael, et al.,

I was using a total station for the first time over the weekend plotting corners of graves in a cemetery. The eastings, northings and elevation of each point were recorded.

Unfortunately, I moved the total station at one point and forgot to update the station's position, so it gave me coordinates based on its previous position. I know the distance and direction from the first TS position and the second TS position. Is there some method to correct the other coordinates that were collected?

On a similar note, if I take a bunch of coordinates with the total station over a site using an abitrary grid system rather than e.g. UTM, can I later then survey in a local survey benchmark using the total station (relative to the abitrary grid) and then update all the previously recorded grids to have their correct global coordinates? (I haven't recorded data like this yet, but am just wondering if it is even possible before I attempt it).

Thanks in advance for your help,
David

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited April 2011
    David,

    If you know how you need to offset your points to correct their locations you can just select them with the Digitizer Tool, then right-click and select the option to Shift/Offset the points, then provide the desired shift distance and bearing.

    You can change the coordinate/grid system that you are entering coordinates in by changing the projection system on the Projection tab of the Configuration dialog to the desired grid system, then creating the points. You can then reproject everything to some other system by again changing the projection on the Projection tab of the Configuration dialog and exporting to a new file.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • Hunter GeophysicsHunter Geophysics Global Mapper User Posts: 75Trusted User
    edited April 2011
    Thanks for that, Mike. I have managed to fix the data using your instructions.

    Thanks again!
  • Hunter GeophysicsHunter Geophysics Global Mapper User Posts: 75Trusted User
    edited April 2011
    Thanks for that, Mike. I have managed to fix the data using your instructions.

    Thanks again!
  • Hunter GeophysicsHunter Geophysics Global Mapper User Posts: 75Trusted User
    edited August 2011
    Hi Mike,

    Can you please clarify how the projection idea works - i.e. how do I turn a set of TS points based on an arbitrary grid into absolute coordinates? Can you please give step-by-step instructions as I don't really understand how this all works.

    Thanks,
    David
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited August 2011
    David,

    Are you still confused? Sounds like you have it working but then you want instruction? Not sure if the forum posts are out of order.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • Hunter GeophysicsHunter Geophysics Global Mapper User Posts: 75Trusted User
    edited August 2011
    Hi Mike,

    Sorry, I understood how to offset the points (as in para 1 and 2 of my initial post), but didn't understand the solution to the other issue (in para 3).

    Thanks,
    David
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited August 2011
    David,

    Ah for the last one just right-click on the layer in the Control Center and specify to reposition the layer. You can then add control points mapping from the source coordinate system to another. The pending v13 release also adds new options to the right-click shift option to allow shifting from a control point file or by providing an arbitrary set of transformation parameters (i.e. shift, scale, and rotate).

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • Hunter GeophysicsHunter Geophysics Global Mapper User Posts: 75Trusted User
    edited August 2011
    Ah, I see how to do it now. Thanks!
  • Hunter GeophysicsHunter Geophysics Global Mapper User Posts: 75Trusted User
    edited September 2014
    Hi everyone,

    Back again with a similar issue; figured I'd use this conversation rather than starting a new one.

    I've got a whole bunch of points, lines and areas that I surveyed in with a total station. However, the local survey marker (from which I based the entire survey) had incorrect coordinates. So I have a bunch of data that has the wrong coordinates.

    I don't know the correct coordinates for the survey marker and it's likely that the government won't ever update the marker information.

    Instead of having a bunch of data that has erroneous coordinates, is it possible to set one particular point in my dataset (I'm thinking a corner of a fence) as point 0,0 (X,Y), and then shift everything else to be relative to that 0,0 point?

    If so, can you please explain how I should proceed?

    Thanks in advance for your help.
    Dave
  • CJRCJR Global Mapper User Posts: 7
    edited September 2014
    http://www.globalmapperforum.com/forums/raster-data/11619-offsetting-orthophotos.html

    pick the point you want to keep and shift by -ve of the the co-ords. ie Easting 5000 Northing 10000 would mean your shift is -5000 and -10000.
    I'm a surveyor and I am not sure how you have setup over one mark and conducted a survey you need at least 2 points and that should have told you there was a problem.
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