[postgis-tickets] [PostGIS] #4156: ST_ChaikinSmoothing not treating inner and outer rings the same

[PostGIS]

#4156: ST_ChaikinSmoothing not treating inner and outer rings the same
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  Reporter:  komzpa   |      Owner:  nicklas
      Type:  defect   |     Status:  new
  Priority:  medium   |  Milestone:  PostGIS 3.0.0
 Component:  postgis  |    Version:  trunk
Resolution:           |   Keywords:
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Comment (by nicklas):

 Then I agree with you about the results. But I don't see why you expect
 something else. If the last parameter is true (as default or explicit)
 then the start point and end point of each ring is preserved (not moved).
 As mentioned above, that is to not break networks.

 So, what you see is that in your small polygon the start and end point is
 in the lower right corner. So, that is not moved (still sharp), but the
 inner ring of the large polygon have the start and end point in the upper
 left corner so that is not moved. This gives a mismatch both in the upper
 left corner and in the lower right corner. You see the same thing in the
 lower right corner of the large polygon. That is still sharp after
 smoothing, so it seems like that is the start and end of the outer ring.

 If you set the last parameter to false, those start and end points will
 not be preserved and the rings align.

 Maybe this is unclear in the doc?

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Ticket URL: <https://trac.osgeo.org/postgis/ticket/4156#comment:6>
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