ST_Segmentize(geography) fails over the poles

[pramsey]

select st_astext(st_segmentize('linestring(-90 -80, 90 -80)'::geography, 10000));

returns

LINESTRING(-90 -80,3.98389837730904e-308 1.2699287621652e-312,90 -80)

Not sure if this is a result of the "fixes" done or if it's always been this way.

[pramsey]

Oh, I should note that the correct answer is that the segmentized line should travel over the south pole, not make a beeline to the equator and back.

[robe]

Paul,

You sure you updated your PostGIS?

Just tasted with my 2.4.0, which is at:

POSTGIS="2.4.0dev r15313" GEOS="3.6.1-CAPI-1.10.1 r4317" PROJ="Rel. 4.9.1, 04 March 2015" GDAL="GDAL 2.1.3, released 2017/20/01 GDAL_DATA not found" LIBXML="2.7.8" LIBJSON="0.12" LIBPROTOBUF="1.2.1" RASTER

SELECT st_astext(st_segmentize('linestring(-90 -80, 90 -80)'::geography, 10000));

Yields:

LINESTRING(-90 -80,-90 -80.0896860986547,-90 -80.1793721973094,-90 -80.2690582959641,-90 -80.3587443946189,-90 -80.4484304932736,-90 -80.5381165919283,-90 -80.6278026905829,-90 -80.7174887892376,-90 -80.8071748878924,-90 -80.8968609865471,-90 -80.9865470852018,-90 -81.0762331838565,-90 -81.1659192825112,-90 -81.2556053811659,-90 -81.3452914798206,-90 -81.4349775784754,-90 -81.5246636771301,-90 -81.6143497757848,-90 -81.7040358744395,-90 -81.7937219730943,-90 -81.883408071749,-90 -81.9730941704037,-90 -82.0627802690584,-90 -82.1524663677131,-90 -82.2421524663678,-90 -82.3318385650226,-90 -82.4215246636773,-90 -82.5112107623321,-90 -82.6008968609868,-90 -82.6905829596415,-90 -82.7802690582962,-90 -82.869955156951,-90 -82.9596412556057,-90 -83.0493273542604,-90 -83.1390134529152,-90 -83.2286995515699,-90 -83.3183856502246,-90 -83.4080717488793,-90 -83.497757847534,-90 -83.5874439461888,-90 -83.6771300448435,-90 -83.7668161434982,-90 -83.8565022421529,-90 -83.9461883408077,-90 -84.0358744394624,-90 -84.1255605381171,-90 -84.2152466367719,-90 -84.3049327354266,-90 -84.3946188340813,-90 -84.4843049327361,-90 -84.5739910313908,-90 -84.6636771300456,-90 -84.7533632287003,-90 -84.8430493273551,-90 -84.9327354260098,-90 -85.0224215246645,-90 -85.1121076233193,-90 -85.201793721974,-90 -85.2914798206288,-90 -85.3811659192835,-90 -85.4708520179382,-90 -85.5605381165929,-90 -85.6502242152477,-90 -85.7399103139024,-90 -85.8295964125572,-90 -85.9192825112119,-90 -86.0089686098667,-90 -86.0986547085214,-90 -86.1883408071761,-90 -86.2780269058309,-90 -86.3677130044857,-90 -86.4573991031403,-90 -86.5470852017951,-90 -86.6367713004498,-90 -86.7264573991046,-90 -86.8161434977594,-90 -86.9058295964142,-90 -86.995515695069,-90 -87.0852017937237,-90 -87.1748878923785,-90 -87.2645739910333,-90 -87.3542600896881,-90 -87.4439461883427,-90 -87.5336322869974,-90 -87.6233183856521,-90 -87.7130044843069,-90 -87.8026905829617,-90 -87.8923766816164,-90 -87.9820627802713,-90 -88.0717488789258,-90 -88.1614349775806,-90 -88.2511210762354,-89.0947714037136 -88.3366646427364,-88.0916965251009 -88.4217483422378,-86.974726692136 -88.5062935885788,-85.7243031573594 -88.590203505604,-84.3164176784212 -88.6733575344074,-82.7213911608027 -88.7556041340313,-80.9022896158874 -88.8367508113901,-78.812888499932 -88.9165503970155,-76.3951115635852 -88.9946820535433,-73.5759485253912 -89.0707249768823,-70.2640854352177 -89.1441222472901,-66.3470434742355 -89.2141322309357,-61.6908428093039 -89.2797664703663,-56.1465255923405 -89.3397187812369,-49.5713364425753 -89.3923051733096,-41.8747916581447 -89.4354634814135,-33.0933739616388 -89.4668989559672,-23.4697696521758 -89.4844626789646,-13.4706309962476 -89.486728629755,-3.68177286358059 -89.4734992558896,5.3792186484485 -89.445883287127,13.4017800642145 -89.4058835187265,20.2966553608761 -89.3558026551952,26.1262404353484 -89.2977943259407,31.0242145309819 -89.2336566290509,35.1408243678647 -89.1648004552211,38.6155300765856 -89.0922989694398,41.5672026259864 -89.0169583904874,44.0930543619685 -88.9393835683664,46.2710539835526 -88.86003053202,48.1632686374747 -88.7792460015835,49.819069983912 -88.6972962634541,51.2778530351794 -88.6143880450867,52.5712182717433 -88.5306835882621,53.7246774293682 -88.4463115789166,54.758971090766 -88.3613751296882,55.6910823354785 -88.2759576614321,56.5350169956248 -88.1901272783686,57.3024062234211 -88.1039400548554,58.0029741091342 -88.0174425288569,58.6449026828556 -87.9306736118006,59.2351186178144 -87.8436660650299,59.7795199039657 -87.7564476513836,60.2831562408948 -87.6690420410241,60.7503735347993 -87.5814695297195,61.1849303802674 -87.4937476127798,61.5900925395971 -87.4058914469887,61.9687100337318 -87.3179142249492,62.3232804067573 -87.2298274804278,62.6560009302798 -87.141641338955,62.9688119090345 -87.0533647247009,63.2634327864018 -86.9650055322018,63.5413923926389 -86.8765707696623,63.8040544033041 -86.788066679133,64.0526388611431 -86.6994988377763,64.2882404470905 -86.6108722435809,64.5118440541854 -86.5221913882251,64.7243381139095 -86.4334603192695,64.9265260415498 -86.3446826934499,65.1191361009432 -86.2558618225122,65.302829935781 -86.1670007127759,65.4782099717441 -86.0781020993979,65.6458258589861 -85.9891684761454,65.8061800961873 -85.9002021213457,65.9597329542782 -85.8112051205714,66.1069067989679 -85.7221793865294,66.2480898955692 -85.6331266765454,66.3836397666911 -85.5440486079757,66.5138861626387 -85.4549466718262,66.6391336954229 -85.3658222448162,66.7596641798105 -85.276676600091,66.8757387185795 -85.1875109167538,66.9875995638769 -85.0983262883679,67.0954717821276 -85.0091237305556,67.1995647461723 -84.9199041878017,67.300073475129 -84.8306685395604,67.3971798397373 -84.7414176057435,67.4910536486355 -84.6521521516646,67.5818536290242 -84.5628728924986,67.6697283134704 -84.4735804973134,67.7548168431353 -84.3842755927182,67.8372496964498 -84.2949587661726,67.9171493511634 -84.205630568991,67.9946308867479 -84.1162915190748,68.0698025333178 -84.0269421034019,68.142766172512 -83.9375827802961,68.2136177951589 -83.8482139815007,68.2824479200028 -83.7588361140749,68.3493419772955 -83.6694495621292,68.414380660636 -83.580054688419,68.4776402500769 -83.4906518358048,68.5391929091928 -83.401241328596,68.5991069585201 -83.3118234737875,68.657447127531 -83.2223985621975,68.714274787074 -83.1329668695182,68.7696481640254 -83.0435286572854,68.8236225397153 -82.9540841737739,68.8762504335401 -82.8646336548267,68.927581773032 -82.7751773246227,68.9776640515352 -82.6857153963878,69.0265424745293 -82.5962480730551,69.0742600955408 -82.5067755478776,69.1208579424919 -82.4172980049985,69.1663751352661 -82.3278156199805,69.2108489951916 -82.2383285602998,69.254315147081 -82.1488369858055,69.2968076144129 -82.0593410491487,69.3383589081863 -81.9698408961825,69.3790001099283 -81.8803366663364,69.4187609493048 -81.7908284929651,69.4576698767343 -81.7013165036756,69.4957541313761 -81.6118008206338,69.5330398048349 -81.5222815608506,69.5695519008899 -81.4327588364509,69.6053143915384 -81.3432327549259,69.6403502696114 -81.2537034193696,69.674681598207 -81.1641709287016,69.708329557162 -81.0746353778754,69.7413144867676 -80.9850968580759,69.7736559289142 -80.8955554569035,69.8053726658471 -80.8060112585491,69.8364827566832 -80.7164643439578,69.8670035718476 -80.6269147909842,69.8969518255623 -80.5373626745376,69.9263436065116 -80.4478080667207,69.9551944068092 -80.3582510369594,69.9835191493694 -80.2686916521255,70.0113322137869 -80.1791299766537,70.0386474608192 -80.0895660726507,90 -80)

[pramsey]

Thanks for the extra poke. Checking the svn tip on all the branches, they all worked for me. So I must have had an old tip I guess at some point where things were broken.