Recording Approximate Contexts in the GIS


  1. The coordinate data of approximate contexts are measured in the field in a dedicated survey project and then brought into the GeoPackage via shapefile export followed by direct entry of additional data. Their recording happens only once (for both day plans and archival purposes) so extra care needs to be given to ensure the accuracy of data entered.
    1. First, locate the shapefile file that includes the latest approximate contexts from your excavation area in QGIS’ Browser panel (it should be in E:\gygaia\gisgps\kap\2023\gnss).
    2. Click on the dropdown arrow on the .shp file to see a layer called “Points.” Right click on “Points” and select Export Layer…> To File…
      1. In the window that opens, select
        1. “Format” = Geopackage
        2. File name = … [browse and locate your EA GeoPackage]
        3. “Layer name” = temp_approx_contexts
        4. In the “Select fields to export and their export options” panel, click “Deselect All” and then check the checkboxes for each of the first 6 fields (Name to Desc), except for Code.
        5. In the Export name column, change “Name” to “context_key” and “Desc” to “context_approx_type”
        6. Check the checkbox at the bottom for “Add saved file to map” and click OK.
    3. If the new temp_approx_contexts layer is not added automatically, add it as a layer to the project from the Browser now, select it in the Layer panel, and Toggle Editing to on.
    4. Open the Attribute Table of temp_approx_contexts and cut and paste all Easting, Northing, and Elevation data for each Approximate Context of the day into the Excavation MS Access form.
    5. Select all the Approximate Contexts of the day, and select Edit> Copy Features.
    6. Select the [EA]_context_approximate_points layer in the Layer panel, Toggle Editing to on, and select Edit> Paste Features.
    7. Open the Attribute Table of [EA]_context_approximate_points, make sure the context_key and context_approx_type fields were transferred correctly, and update the context_number column appropriately. Save edits and Toggle Editing to off.
    8. After transferring all required data, right click on the temp_approx_contexts layer and select Remove Layer. Find temp_approx_contexts in your EA GeoPackage in the QGIS Browser, right click on it, and select Manage> Delete Layer… to remove the temporary layer permanently (remember that the original data is still preserved in the GNSS shapefile if it is needed later).

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