DESCRIPTION

For individual straight parts of the line, the average curvature as calculated from directions of adjacent parts. An average of specified segment is then calculated as average from curvatures of line parts (lengths of line parts overlapped by specified segment are taken into acount).

This method may be used only if line data digitized with appropriate accuracy, where 'appropriate' depend on an application we want to use it for and on the length of the segment we want to calculate the curvature for.

If user needs curvature for too small segments compared to the density of vertices on lines, the lines should be smoothed beforehand with some other module (this approach is preferred to internal smoothing (interpolating) within v.curvature, because automatic smoothing may often result in unexpected, unwanted shapes, and user should see which data are really processed).

With the 'segment' option, the module reads from 'stdin':

• segment_id line_category from to
• segment_id - identifier for one segment we need curvature for
  • line_category - category of line the segment is on:
    • from - distance of segment start from the beginnig of the line
    • to - distance of end of segment from the beginnig of the line
  Note that if segment limits may exceed the line, segment is cut by line ends.

  segment_id average_curvature average_radius

AUTHOR

Last changed: $Date$