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How do I create a cross section in Surfer?

You can use Surfer to create a cross-section by either adding a Profile or by using the Grid Slice command. The former is faster and easier, but the latter allows you to specify exact x,y values for the cross section line that the profile is drawn for.
 

Method 1: To add a profile to an existing map with one or more grid-based map layers:

  1. Select your multi-layer map.
  2. Click Map Tools | Add to Map | Profile.
  3. Click on the map where you want the cross section line to start. Double click where you want the cross section line to end (you can also click along the line of section to include points in between the start and end points). As soon as you double click to end the section line, the profile object is created and placed below the map, and a base layer is added to your existing map containing the cross section line you just drew. If the map contained multiple layers from different grids, each grid is sliced and added automatically to the profile. You can turn off layers in the profile properties, if desired.
  4. Select the Profile object in the Contents window. Choose the appropriate surface from the Current profile dropdown list in the Properties window, and then edit the line and fill properties for that surface.
  5. If you wish to edit the location of the Profile line, you can use the Reshape command (Features | Edit Features | Reshape) on the drawn line in the base layer.

 

Method 2: The profile method is quick and easy, but you have to manually draw the cross section line on the map. If you have specific XY values that you need to use for the cross section line, you will instead want to use the Grid Slice command. This option extracts a slice through the grid along the trace defined by a polyline. The polyline can be drawn on the map as part of a base layer, or it can be in a vector file format (e.g. BLN, BNA, SHP, DXF, etc.). If you have already used the Profile command, the line drawn on the base map can be selected in the Grid Slice dialog. 

If you have the XY values for the section line, an easy vector format to create is the BLN format. It is an ASCII format consisting of a header line with the number of vertices, followed by the XY coordinates of the vertices. The following example draws a line from (1.0,1.0) to (2.0,3.0).

2
1.0 1.0
2.0 3.0

You can create this file in Notepad or in the Surfer worksheet. More information about creating a BLN file can be found here.

Once you have one or more grid files and the polyline defining the section line saved either as a vector file or drawn on the map, then:

  1. Click Grids | Calculate | Slice.
  2. In the Grid Slice dialog, in the Input Grid section, either select a grid-based layer created from your grid file, or click the Browse button to navigate to and select the grid file.
  3. In the Slice Line section, either select a base layer created from your vector file or the base layer with the drawn line on it, or click the Browse button to navigate to and select the vector file.
  4. The Output BLN field will be checked by default and is the appropriate file type. Change the file name and/or click the Change Filename button to change the save location. 
    • If you would also like a DAT file, check the box next to Output DAT. The DAT file differs from the BLN in that it will export the coordinates as well as Z values, where the BLN just exports the X coordinate and the Z coordinate necessary to create the profile line. 
    • If you wish, you can choose to set values outside of the grid to a specified value, and also to remap NoData values to a different value.
  5. Click OK to generate the BLN file.
  6. Back in the plot window, click Home | New Map | Base | Base.
  7. In the Import dialog, select the newly saved BLN file and click Open.
  8. The map is created with proportional scaling. If you would like to increase the vertical exaggeration,
    1. Select Map in the Contents window.
    2. In the Properties window, on the Scale page, uncheck Proportional XY scaling.
    3. If you see a Surfer Warning telling you the width or height will be less than 0.25 inches, click OK to continue.
    4. In the X Scale and/or Y Scale section, enter the desired Length in page units. For example, enter 6 inches for the X Scale Length and 1.5 for the Y Scale Length to match the default scaling of a profile. 
  9. Select the Base layer in the Contents window.
  10. On the General page in the Properties window, change the Color in the Line properties section.
  11. Repeat steps 1-8 for any other grid files you want to be part of your profile line, but click Home | Add to Map | Layer | Base during step 8 rather than Home | New Map | Base | Base, so each new section is added to the existing profile rather than added to a new profile.

 

For different fill colors and patterns, you can convert the polylines in each Base layer to a polygon and fill the polygon. To do this:

  1. In the Contents window, expand then select the Base layer.
  2. Click Features | Group | Start Editing.
  3. Select the Polyline within the Base layer.
  4. Click Features | Edit Features | Reshape.
  5. Select the farthest node to the right, hold the CTRL key down and click below the bottom axis and to the right of the right axis.
  6. Select the farthest node to the left, hold the CTRL key down and click below the bottom axis and to the left of the left axis. 
  7. Press ESC to exit reshape mode.
  8. Click Features | Change Type | Change Type | Polyline to Polygon. Now the surface is a polygon which can be filled.
  9. Click Features | Group | Stop Editing to exit editing mode.
  10. With the polygon selected, on the Fill page in the Properties window, change the fill properties as desired.
  11. Repeat steps 1-10 for any other Base layers.
  12. If necessary, click and drag the base layers in the Contents window so the layer with the shortest elevation is at the top of the list of layers in the Contents window, and the layer with the tallest elevation is at the bottom of the list.

Another option is to create the slice DAT files in Surfer, and create the cross-sections in Grapher using the DAT files. Grapher has the ability to add fill between curves, simplifying the process of displaying the data.


See also: How can I create a BLN file

 

Updated May 22, 2018

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