[postgis-devel] [PostGIS] #1926: ST_Linecurve creates a strange multi-linestring

[PostGIS]

#1926: ST_Linecurve creates a strange multi-linestring
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 Reporter:  lexman   |       Owner:  pramsey
     Type:  defect   |      Status:  new    
 Priority:  medium   |   Milestone:         
Component:  postgis  |     Version:  2.0.x  
 Keywords:           |  
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 Hi there,

 I've encountered a strange behaviour with ST_Linecurve you might be
 interested in.

 When I run this query with a certain geometry you'll read furter :
     SELECT asText(ST_Reverse(ST_OffsetCurve(geom,-5000)))
 I get a multilinestring as a result : there is a useless extra linestring
 on the result !


 What is strange, is that it works if I run :
    SELECT asText(ST_Reverse(ST_OffsetCurve(geom,-4000)))
 it works !

 -------

 Postgis version : "POSTGIS="2.0.2SVN r10051" GEOS="3.3.3-CAPI-1.7.4"
 PROJ="Rel. 4.7.1, 23 September 2009" GDAL="GDAL 1.9.0, released
 2011/12/29" LIBXML="2.8.0" RASTER" under linux

 I'm working with cs : +proj=gall +lon_0=0 +x_0=0 +y_0=0 +ellps=WGS84
 +datum=WGS84 +units=m +no_defs

 The geom in question :

 LINESTRING(397136.991825913 4765760.97735032,397118.273454364
 4765736.97457462,397070.469976475 4765673.66177918,397031.537652807
 4765626.38115555,397004.215757245 4765592.91344897,396978.672815412
 4765561.6196266,396938.197682314 4765512.86751546,396880.51550119
 4765442.28706088,396820.566334781 4765369.15954307,396783.893124921
 4765325.1292299,396749.604972495 4765284.14458692,396742.04835488
 4765273.96637409,396735.908603068 4765266.83370408,396725.864598822
 4765254.94592836,396694.323591758 4765214.56152719,396685.184807331
 4765202.86626138,396651.085570345 4765156.88912486,396608.327709009
 4765091.65414166,396585.484683679 4765056.86302279,396540.137106515
 4764981.00893023,396525.118329006 4764955.84130738,396514.090390175
 4764936.27784059,396507.509835669 4764924.24315133,396478.511315573
 4764869.10787018,396455.054315061 4764820.00707477,396437.319878097
 4764780.24653141,396416.979982351 4764730.39882547,396404.495820334
 4764698.32565702,396384.683313526 4764647.30081938,396374.190635109
 4764614.85423119,396356.873386409 4764565.06368724,396348.8759661
 4764541.05152697,396338.855576284 4764510.17880665,396329.307475069
 4764475.83057511,396318.326765098 4764433.2972952,396309.172237717
 4764391.884919,396304.740596345 4764369.55986971,396295.578197487
 4764320.32487732,396289.965834613 4764286.18086273,396283.157007284
 4764247.99535867,396282.306887802 4764241.84810172,396280.417733398
 4764224.65164507,396273.530191302 4764171.53407877,396263.549158869
 4764099.7713263,396259.117517497 4764049.25798336,396255.095192913
 4764015.35232864,396249.341143458 4763954.33366625,396244.445084962
 4763911.76792061,396240.776976829 4763887.7454979,396208.684966397
 4763650.05919474,396204.150995828 4763608.36599574,396198.373331944
 4763565.29182559,396176.522112675 4763401.91676771,396171.744126329
 4763366.17871378,396169.130796071 4763341.39872,396149.349775169
 4763207.14145641,396128.395904242 4763088.33724423,396113.259054583
 4763012.4932236,396096.854897178 4762940.27196457,396078.65604309
 4762867.0096299,396057.347955712 4762790.78186805,396043.053354058
 4762743.92926979,396012.645839636 4762644.27035768,395992.368915704
 4762576.98625514,395970.029664881 4762507.47249881,395932.600793259
 4762400.57068974,395852.563618358 4762164.37973867,395829.16958966
 4762100.84449426,395765.229584573 4761916.95264158,395695.511915603
 4761737.45484095,395627.533842978 4761592.62893323,395600.298533659
 4761538.16253346,395532.281103652 4761436.77995256,395512.460725367
 4761403.02741501,395493.089021253 4761366.32076872,395484.973528794
 4761336.12246116)

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/1926>
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