[postgis-tickets] [PostGIS] #2232: Accumulated error with relative coordinates in ST_AsSvg

[PostGIS]

#2232: Accumulated error with relative coordinates in ST_AsSvg
---------------------+------------------------------------------------------
 Reporter:  nicklas  |       Owner:  pramsey
     Type:  defect   |      Status:  new    
 Priority:  medium   |   Milestone:         
Component:  postgis  |     Version:  2.0.x  
 Keywords:           |  
---------------------+------------------------------------------------------
 When using ST_ASSvg outputting relative rounded coordinates you might get
 accumulated rounding errors.

 I saw huge errors like that when testing twkb on polygons with thousands
 of vertex-points.

 Example:



 {{{
 select
 st_assvg('LINESTRING(0 0, 0.4 0, 0.8 0, 1.2 0,1.6 0, 2 0)'::geometry,1,0)
 }}}

 returns:

 {{{
 M 0 0 l 0 0 0 0 0 0 0 0 0 0
 }}}

 I fixed it in twkb-case in the spike with #11165, probably the same
 approach can be used here.

 Just not get the relative value as relative to the previous coordinate,
 but relative to the accumulates relative coordinates achieved.

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/2232>
PostGIS <http://trac.osgeo.org/postgis/>
The PostGIS Trac is used for bug, enhancement & task tracking, a user and developer wiki, and a view into the subversion code repository of PostGIS project.