[GRASS-dev] [GRASS GIS] #3419: v.to.db sinuous

[GRASS GIS]

#3419: v.to.db sinuous
------------------------+------------------------------------
  Reporter:  jradinger  |      Owner:  grass-dev@…
      Type:  defect     |     Status:  new
  Priority:  normal     |  Milestone:
 Component:  Vector     |    Version:  7.2.2
Resolution:             |   Keywords:  v.to.db, shape metrics
       CPU:  All        |   Platform:  All
------------------------+------------------------------------

Comment (by mmetz):

 Replying to [ticket:3419 jradinger]:
 > The option of v.to.db to calculate sinuosity (sinuous) seems to be
 calculated based on features (i.e. feature ids) rather than on cats (e.g.
 as length is calculated). Thus, only reasonable results are calculated if
 a cat consists of only one feature. For connected lines that consist of
 more than one feature (lines) it is unclear how the sinuosity index is
 calculated (based on last processed feature? average over all sub-lines).

 The sinuosity index is sinuosity of the last feature processed. For
 multiple lines with the same category, how should sinuosity be calculated?
 Average of all sinuosities or sum of all line lengths / sum of all
 endpoint distances?

 Line slope is currently the sum of all line slopes, that does not seem
 right.

 Azimuth is the azimuth of the last feature processed. Since azimuth is an
 angle, a simple average over all lines with the same category would not
 work.

 > For connected lines that share one cat the sinuosity should probably be
 calculated based on a polyline of these lines sharing a common cat.

 In this case polylines would need to be built first, before running
 v.to.db.

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/3419#comment:1>
GRASS GIS <https://grass.osgeo.org>