Ticket #4143 (closed defect: fixed)

Opened 5 months ago

Last modified 4 months ago

MapServer polygon simplifier discards too many points

Reported by: dr Owned by: tbonfort
Priority: high Milestone: 6.2 release
Component: MapServer C Library Version: svn-trunk (development)
Severity: major Keywords:
Cc:

Description

See  #1 and  #2. Mapfile is located here:  http://gis-lab.info/share/DR/mcx.map I've made public wms service:  http://gis-lab.info/cgi-bin/mapserv?map=/usr/home/tenzorr/temp/wms/mcx.map

Change History

Changed 5 months ago by tbonfort

Is your postgis source polygon or polyline data ?

try adding 

PROCESSING "APPROXIMATION_SCALE=FULL"

to your layer definition

Changed 5 months ago by dr

Source data is polygonal.

Thanks, with this directive my map looks better! But I can't find any information about this in documentation.

Changed 5 months ago by tbonfort

  • status changed from new to assigned
  • component changed from WMS Server to MapServer C Library
  • summary changed from MapServer rendering at the lowest zoom levels to MapServer polygon simplifier discards too many points

The feature is currently undocumented, you are correct. the relevant code is in mapdraw.c (reading of the processing key) and mapprimitive.c (transformation from geo to pixel)

There's a bug in the simplifying code that needs to be fixed, renaming this ticket. The simplifier should keep at least 4 points of the original polygon instead of the 3 as it does actually, as 3 points results in a degenerate polygon (i.e. point[0],point[1],point[0] is a line segment, not a polygon)

Changed 5 months ago by tbonfort

  • priority changed from normal to high
  • severity changed from normal to major
  • milestone set to 6.2 release

Changed 4 months ago by tbonfort

fixed in r13058 .

Changed 4 months ago by tbonfort

  • status changed from assigned to closed
  • resolution set to fixed
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