Smooth the map

Shapefiles with polygons typically contain too many data points and too much detail for statistical map visualizations. The excess details can be distracting and negatively impact performance. You can reduce the level of detail and generalize the map with smoothing. The map will look crisper and render more quickly as a result. This option is not available for point and polyline maps.

Max. angle. The maximum angle, which must be a value between 1 and 20, specifies the tolerance for smoothing sets of points that are almost linear. A larger value allows more tolerance for the linear smoothing and will subsequently drop more points, resulting in a more generalized map. To apply linear smoothing, the Map Conversion Utility checks the inner angle formed by every set of three points in the map. If 180 minus the angle is less than the specified value, the Map Conversion Utility will drop the middle point. In other words, the Map Conversion Utility is checking whether the line formed by the three points is almost straight. If it is, the Map Conversion Utility treats the line as a straight line between the endpoints and drops the middle point.

Percent to keep. The percentage to keep, which must be a value between 90 and 100, determines the amount of land area to keep when the map is smoothed. This option affects only those features that have multiple polygons, as would be the case if a feature included islands. If the total area of a feature minus a polygon is greater than the specified percentage of the original area, the Map Conversion Utility will drop the polygon from the map. The Map Conversion Utility will never remove all polygons for the feature. That is, there will always be at least one polygon for the feature, regardless of the amount of smoothing applied.

After you choose a maximum angle and percentage to keep, click Apply. The preview will update with the smoothing changes. If you need to smooth the map again, repeat until you obtain the level of smoothness you want. Note that there is a limit to the smoothing. If you repeatedly smooth, you will reach a point when no additional smoothing can be applied to the map.