Geoprocessing considerations for vertical line segments

A vertical line segment is a portion of a line that is entirely vertical; that is, both vertices that compose the segment's endpoints have the same x- and y-coordinates but different z-coordinates. Vertical line segments may be individual features, or they may be contained in features that have other segments that are not vertical, composing a hybrid polyline.

Vertical and hybrid polylines

In the image above, the orange feature on the left represents an individual polyline feature that is composed of a vertical segment. The black dot below the feature shows how this vertical polyline is represented in 2D the x- and y-coordinates for both segment endpoints are the same, so in 2D, the vertical line only appears as a point). The orange feature on the right represents a hybrid polyline feature in which one segment of the line is vertical but other line segments are horizontal or sloping (not vertical). The black line below this feature shows how this hybrid polyline is represented in 2D.

Some geoprocessing tools support vertical line segments and preserve these segments in the tool output, while others strip or flatten vertical segments.


Vertical line segments are only supported in an ArcGIS 10 or later geodatabase. This includes file and enterprise geodatabases. To upgrade a geodatabase to the latest version, use the Upgrade Geodatabase tool. Earlier version geodatabases, as well as other geodata formats such as shapefiles, do not support vertical line segments.

Tools that support vertical line segments

The following geoprocessing tools support vertical line segments:

Tools that strip, flatten, or remove vertical line segments

Overlay tools such as Intersect and Union, which planarize feature geometries, flatten vertical line segments (see the tool help for more information about what the respective tool does to feature geometries). Tools that aggregate and combine feature geometries, such as Dissolve, may also flatten vertical line segments. Tools that convert between geometry types, such as Feature To Line, may also flatten vertical line segments.