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Problem: Contour lines look blocky, appearing to trace raster cell boundaries

Description

Occasionally, contours may be created that have square or blocky outlines, appearing to follow raster cell boundaries.

Cause

The raster values are integers, which align with the contour. This is not a bug, it is exact contouring of the data.

Solution or Workaround

If you want smoother contours, select one of the options below:

  • Smooth the surface
    This is used to perform a FocalStatistics on the raster with the mean statistic. To use the FocalStatistics tool, have Spatial Analyst installed.
  • Adjust the Base contour
    This offsets the Base contour so that the contours no longer pass directly through the mesh points. The offset can be very small; values as small as 0.0001 are effective.
  • Smooth the surface and adjust the Base contour combined
    Combining both methods is particularly effective. It produces smoother, therefore aesthetically more pleasing contours.

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