Smoothing Contours

Contour smoothness controls the angularity, or roundness, of the contour lines. Smoothness in a contour map can be controlled in several ways:

  • By using Grids | New Grid | Grid Data to produce a denser grid file from your original data. As a rule, contour maps made from high-density grids are visibly smoother than contour maps made from low-density grid files. For example, a 10 X 10 grid file (10 rows and 10 columns) results in more angular contours than a 50 X 50 grid file.

  • By using the Grids | Edit | Spline Smooth command to insert additional rows and columns into an existing grid file.

  • By using the Smooth tool in the Grid Editor.

  • By using the Grids | Resize | Mosaic command to resample an existing grid file.

  • By changing the Smoothing option in the contour map general properties. If smoothing is enabled, contour lines may cross. The Smoothing option in the contour map properties applies a constrained spline smoothing algorithm to interpolate additional contour vertices. Each line is separately calculated, thus the lines can cross if too much smoothing is applied.

  • By using Grids | New Grid | Grid Data to change the gridding method or gridding method parameters. Some methods produce smoother grids than others, and some have smoothing parameters that can be utilized during gridding. See Creating Grid Files for more information on gridding.

If you perform the smoothing by creating a new grid, click on the contour map to select it. In the Properties window, click on the General tab. Click the button next to Grid file to replace the old grid in the contour map. Use the Grid Editor | Options | Update Layer command to update the grid in the contour map if you perform the smoothing with the grid editor.

See Also

Drawing Contours

Creating a New Contour Map

Contour Map Properties