Resolve seam between combined grids in Surfer

If mosaicking your grid files is leaving a contact/seam, convert the grids to data files, merge the data files, and regrid the data. The exact steps are:

  1. Convert the grids to data files:
    1. Click Grids | Edit | Convert.
    2. If you know the spacing of the nodes in the grid file, you can skip this step. Otherwise, select the first grid file, in the Grid Info section note the Size (rows and columns) of the grid file, and click Open.
    3. In the Save Grid As dialog, select DAT XYZ (*.dat) as the Save as type, give the file a name and click Save.
    4. In the Export Options dialog, check the box next to Don't export nodata nodes (blank nodes) and click OK. This is very important and will remove the gaps as desired. 
    5. Repeat steps 1.1-1.5 to create a DAT file for each grid you'd like to mosaic.

  2. Combine the data files:
    1. Click File | Open in worksheet, select one DAT and click Open. It will open in the Surfer worksheet.
    2. Scroll to the bottom of the file and click in the first empty cell in Column A.
    3. Click Data | Edit | Merge.
    4. Select the second DAT file and click Open. The new data will be appended to the bottom of the first file. Repeat as needed until all DAT files have been added. 
      • Note: if your file is very large, sort the data in the worksheet before gridding (select all 3 data and click Data | Data | Sort and sort by the column with X values). Surfer will sort the data points while gridding, but this can save you some time with very large files. 
    5. Once all the DAT files have been added, click File | Save (or File | Save As).

  3. Regrid the data:
    1. Click Home | Grid Data | Grid Data, select the DAT file and click Open.
    2. In the Grid Data dialog, choose the Nearest Neighbor gridding method and set either the Spacing or the # of Nodes equal to that of the original grid file (noted in Step 1.2 above). Set the file path and file name for the output grid file and click OK.



Updated December 2021

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