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Converting from a local grid to known grid system

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    Jennifer Woodson

    Hi Garth,

    You can do the coordinate transformation in Surfer as long as the local system is based on a predefined projection; directions for this workflow are below. If the local system coordinates are not based on one of the predefined projections, then Surfer will not work for this task. However, I have added your voter for this feature in our suggestion list. 

    If you know 3 or more points in both the local and the target coordinate system, I suggest using our Didger software. You can import your points in the local system (they would create a map on the screen), then click Map | Coordinate Conversion. You would tell Didger what the target coordinate system is (MGA94 Zone 50), enter the coordinates for the 3 known points, and then click on the map in those 3 locations. Didger would convert the coordinates for the entire project to your chosen coordinate system. Then, you can click File | Export and export the data to a new file in the new coordinates.

    Please see below to convert from a local system using a known projection to a different coordinate system in Surfer:

    1. Open the data file in the worksheet with the File | Open command.
    2. In the worksheet, click Data | New Projected Coordinates.
    3. Click the (…) button next to the Source Coordinate System.
    4. You are then asked to specify the coordinate system of your data. This would be your local system. Click the New Geographic System button to define your own coordinate system. You would need to enter a projection for the local system and a datum. You can create a custom datum, but you cannot create a custom projection.  
    5. Click OK.
    6. Click the (…) button next to the Target Coordinate System.
    7. Navigate to and select the desired coordinate system.
    8. Click OK.
    9. Click OK in the New Projected Coordinates dialog.

     

    Thanks,

    Jennifer

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    Garth Cooper

    Thanks for getting back to me quickly.

    Are there notes to define a local system in Surfer? In the define coordinate system there are options to define a projection and datum but I can find any documentation on how to define the datum.

    Could you point me to some materials on how to define the Ellipsoid and Prime Meridian?

    Garth 

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    Jennifer Woodson

    Hi Garth, 

    You can edit the datum from the Assign Coordinate System dialog. Please see this article: Custom Datum Definition.

    Thanks,

    Jennifer

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