[postgis-tickets] [PostGIS] #3712: Address MVT issues reported by specification author

[PostGIS]

#3712: Address MVT issues reported by specification author
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  Reporter:  strk     |      Owner:  Björn Harrtell
      Type:  defect   |     Status:  new
  Priority:  blocker  |  Milestone:  PostGIS 2.4.0
 Component:  postgis  |    Version:  trunk
Resolution:           |   Keywords:
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Comment (by Björn Harrtell):

 Thanks @flippmoke. I'm all for making the world more OGC valid. :) It's a
 good thing for other things than triangulation too.

 I have just investigated how to make sure "snap rounding" does not risk
 invalidating polygons and it turns out it's not as easy as I thought and
 might require turning to GEOS anyway. This function calculates exactly
 what the tolerance for snap rounding is:

 http://postgis.net/docs/ST_MinimumClearance.html

 As the documentation explains it involves calculating a value e so that
 "No vertex is closer than e to a line segment of which it is not an
 endpoint" and under the hood this is done using JTS/GEOS index/algorithms
 which might be non-trivial to implement in C.

 I'll spend some more time thinking about it and would appreciate further
 input on the subject but ST_MakeValid is starting to look pretty good
 after all.

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Ticket URL: <https://trac.osgeo.org/postgis/ticket/3712#comment:14>
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