[postgis-tickets] [PostGIS] #3719: Error: Invalid number of points in LinearRing

[PostGIS]

#3719: Error: Invalid number of points in LinearRing
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  Reporter:  tiiipponen  |      Owner:  pramsey
      Type:  defect      |     Status:  new
  Priority:  medium      |  Milestone:  PostGIS Fund Me
 Component:  postgis     |    Version:  2.3.x
Resolution:              |   Keywords:
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Comment (by tiiipponen):

 Hi. Nice to hear that this is taking steps forward.
 I agree the tolerance concept with minimum of two (or five and maximum of
 ? (10 000?)) segments can be good fix here.
 I looked from one of our data, what is the smallest tolerance to keep arcs
 with two segments and here are the results in ascending order:
 {{{
 order_id     tolerance
 ----------------------
 1            0.0 (under accuracy of presentation maybe)
 2            1.8189894035458565e-12
 ...
 158          1.3274114678551996e-6
 ...
 516          0.00011366017865555023
 ...
 698          0.00100533397314706
 ...
 848          0.010147203454144105
 ...
 1157         0.1016548941997506
 ...
 }}}

 That is real life example and "minimum of 2 segments" parameter is needed.

 The question then rises: what is the default tolerance for linearization?
 In Oracle we have used tolerance 0.0005 in metadata
 "user_sdo_geom_metadata".
 I have not seen place to put tolerance for table-data in PostGIS. At least
 it is not in view "public.geometry_columns".
 I can imagine that not everybody are satisfied with highest possible
 tolerance, because of its impact to efficiency.
 On the other hand too big tolerance gives more erroneus results from
 functions like ST_Intersects() etc.
 It would be good if users could select tolerance as they want in table
 level or somehow.
 I am willing to hear your thoughts about this.

 I am also willing to hear your thoughts about PostGIS's future development
 for arc-geometry handling. Are there plans to do topology- queries etc.
 without need to linearizing arcs? I can see some similar base development
 done to PostGIS code already.

-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/3719#comment:11>
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