[postgis-tickets] [PostGIS] #2227: Visvalingam line generalization function

[PostGIS]

#2227: Visvalingam line generalization function
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 Reporter:  strk         |       Owner:  nicklas      
     Type:  enhancement  |      Status:  new          
 Priority:  medium       |   Milestone:  PostGIS 2.2.0
Component:  postgis      |     Version:  trunk        
 Keywords:               |  
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Comment(by nicklas):

 I think that I vote for keeping area "as is" and relying on doc because
 the area concept is quite  intuitive. If you know how the algorithm works
 you can even check the result by just measuring the area in the client (If
 you see what will be the next point to remove)

 About names I guess you are right. If I understand you right you mean that
 we have separate ST_SimplifyDP, ST_SimplifyVisvalingam and then we have
 ST_Simplify with _ST_Simplify that picks the right one?
 Is the functions picked by some function-ID from the planner so there is
 no parsing for each row?

 About z vs m:
 Will it make sense to put the area in z?
 When converted to many formats like geoJSON it will be the third
 coordinate anyway if there is no z-value. But it is no big deal to
 implement a choice between z and m. It could also be as an array in a
 separate column, but that will need some more fiddling to get working.

 Yes, the client can use the area-values as is. No more calculations. The
 area registered is the area each point represents when all with lower area
 is removed. It is not the area it represents in the untouched geometry.

 It is possible to get confused about that "If the recalculated area of an
 adjacent vertex is smaller than the previous the adjacent vertex gets the
 same higher area" That is to ensure that the points gets removed in the
 right order.

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/2227#comment:13>
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