Export Contours

To retain the Z information for contour lines for use in other mapping programs, click the Map Tools | Layer Tools | Export Contours command or the button. The Export Contours command exports the currently selected contour map as an AutoCAD .DXF, 2D Esri .SHP, 3D Esri .SHP, or a .TXT text format.

Surfer prompts to save the coordinate system and projection information, if one is specified for the map. The Export Options dialog appears with the option to save the coordinate system information. It is recommended to check the GS Reference (Version 2) file if you intend to use the grid file in Surfer, as the GSR2 retains all of the information needed. The grid has the same coordinate system as the original data file, but the .GSR2 is required to define the coordinate system.

Export vs Export Contours

The File | Export command can be used to export Z information to an attribute field for BLN, BNA, DXF, GSB, GSI, KML, KMZ, MIF, and SHP files. The Export command can also export 2D or 3D BLN, DXF, SHP, or XYZ Points files. However, the Export command will also export any other visible items in the map, including contour labels. The Export Contours command automatically removes the contour labels from the output and closes the gaps where the labels were, and the Export Contours command only exports the contours lines, regardless of which items are visible in the map.

Export File Types

The following file types are available for export when using the Export Contours command.

AutoCAD DXF

The contours are saved as elevated polylines. The POLYLINE entities in the DXF have X and Y coordinates for each vertex, and the Z coordinate is stored as an attribute for the lines. The polylines are clipped to the map limits and scaled to the current map scale. Axes, labels, contour fills, line properties (width, style, and color), etc. are not exported. The contours are not affected by 2D page transformations or rotations. The coordinates in the AutoCAD .DXF file are saved with 64-bit floating-point precision.

Use the File | Export command with the Write LWPOLYLINE entities even when 3D data is available export option cleared to export the contours as POLYLINE entities with the Z values written for each vertex. Use the File | Export command with the Write LWPOLYLINE entities even when 3D data is available export option checked to export the contours as LWPOLYLINE entities with the Z values as an attribute for each line.

2D SHP

The 2D .SHP exports a shape 2D polyline type where each vertex along the line comprises an X and Y coordinate. The Z coordinate for each vertex is stored in the associated .DBF file.

3D SHP

The 3D .SHP exports a shape polyline Z type where each vertex along the line comprises an X, Y, and Z coordinate. The Z coordinate for each vertex is also stored in the associated .DBF file.

Text Format

The text format .TXT exports each contour line as a series of X, Y, Z points. Each point is on a separate line in the .TXT file. This file type is similar to the DAT or CSV XYZ Points file type.

To export 3D contour lines

Create a contour map by clicking the Home | New Map | Contour command. Select the .GRD file and click Open.
Select the contour map by clicking on Contours in the Contents window. It does not matter if the contour map is overlaid with other maps as long as only the contour map is selected.
Click Map Tools | Layer Tools | Export Contours to display the Save As dialog. Enter the File name, specify the Save as type, and click Save. The file is exported with the specified extension. The selected file format and a .GSR2 and a .PRJ file are created.

If you would like to export the contours as part of a complete map, choose one of the export options in File | Export.