[postgis-users] Problem : Within() incorrectly returns 'false'

Paul Ramsey pramsey at refractions.net
Tue Jan 9 08:48:25 PST 2007

```If this is a recent PostGIS, it's possible that our point-in-polygon
short-circuit test is returning a wrong answer, while the other tests
(distance, intersection) are independently returning the right answer.
Incidentally, what is the result of a relate(point,polygon)?

P

Emily Gouge wrote:
>
> You could try using the relate() function instead of within.
> relate(point,polygon,'T*F**F***')
>
> Arnaud Lesauvage wrote:
>> Martin Davis a écrit :
>>
>> All my other tests run fine :
>> Distance() returns 0, Intersects returns true, both geometries are
>> valid...
>> I don't know what to do next !
>>
>> SELECT Intersects(pt,pg), Distance(pt,pg), Within(pt,pg), IsValid(pg),
>> IsValid(pt)
>> FROM
>> (SELECT GeomFromText('POINT(455663 4973705)',32631) AS pt,
>> GeomFromText('POLYGON((455634.327007261 4973739.18140708,455640.390824553
>> 4973742.34545851,455649.974963534 4973744.72838799,455655.302230411
>> 4973744.81018619,455666.871609771 4973741.51734043,455673.066844244
>> 4973737.99160574,455682.857256671 4973731.31013028,455696.77629443
>> 4973721.97329467,455713.453957339 4973712.16884477,455721.42334697
>> 4973707.86016838,455737.50239802 4973705.84732456,455748.289255495
>> 4973707.80971155,455768.964516862 4973713.10563678,455789.467434074
>> 4973718.30527948,455809.877573217 4973718.59365931,455816.032949075
>> 4973711.16573985,455819.835126931 4973702.44653788,455824.05944495
>> 4973691.47543162,455824.05944495 4973691.47543162,455828.610407021
>> 4973680.12283995,455830.970634323 4973674.90248145,455833.367228335
>> 4973670.30554483,455838.223766503 4973663.87857158,455853.056176824
>> 4973662.3695754,455866.6601998 4973666.33738459,455872.247284383
>> 4973667.83016243,455891.21742699 4973672.66515592,455904.87965274
>> 4973676.20206359,455925.323306466 4973681.93577574,455931.93236638
>> 4973683.83511874,455963.188375863 4973690.90230387,455986.900652308
>> 4973690.57770489,455999.308881106 4973688.08608035,456006.847072463
>> 4973685.91128035,456013.781894891 4973682.68047389,456020.04917607
>> 4973677.53977996,456028.058802994 4973664.42994524,456032.395247822
>> 4973652.08166202,456034.250253643 4973645.32660031,456037.315382866
>> 4973631.6242598,456038.518126576 4973625.06483024,456039.49606989
>> 4973618.95846064,456041.143946469 4973604.12669801,456041.322480722
>> 4973600.16812515,456041.234269879 4973593.33220285,456040.255579245
>> 4973584.79199929,456038.077220394 4973576.88018093,456031.407673379
>> 4973564.92278014,456022.584091079 4973553.60498374,456015.530632601
>> 4973545.35673604,456011.870844281 4973541.1846865,456001.221309389
>> 4973529.12192161,455991.929965679 4973518.46446974,455982.111242839
>> 4973507.13762537,455975.429739526 4973499.25369943,455968.699421007
>> 4973481.2156405,455968.569127113 4973472.22440673,455968.681690362
>> 4973469.48222644,455968.364280116 4973459.20668792,455964.198441514
>> 4973452.80965392,455957.352768727 4973451.16429375,455950.970005851
>> 4973451.05854393,455925.042572423 4973453.79303565,455920.580033511
>> 4973454.95190268,455916.338152812 4973456.411639,455908.870067239
>> 4973460.36365329,455899.377173016 4973468.20421239,455892.64054911
>> 4973473.70250239,455884.308266302 4973478.59803378,455873.700962084
>> 4973482.45761784,455861.855176683
>> 4973485.90236361,455859.696574931 4973492.55059044,455844.389439454
>> 4973492.39432963,455839.411700775 4973495.34512154,455831.33685203
>> 4973502.9194365,455825.191393046 4973512.52991105,455822.579473065
>> 4973518.00029755,455817.751828832 4973530.0745478,455812.814767254
>> 4973543.24550764,455807.105870701 4973557.06881857,455803.959640509
>> 4973563.64623146,455796.916583005 4973575.41517021,455792.972660989
>> 4973580.26754987,455786.234602819 4973585.77560012,455773.906298319
>> 4973590.19110681,455755.880529301 4973589.95244674,455741.983929337
>> 4973588.07856712,455734.473975748 4973587.00298353,455726.703007087
>> 4973585.92187192,455710.902303958 4973583.8726695,455695.630378757
>> 4973582.19016965,455688.520382506 4973581.56743626,455675.978583625
>> 4973580.92133312,455661.611205371 4973581.95574872,455651.587526438
>> 4973586.21821552,455646.738207892 4973591.31382874,455642.936132872
>> 4973598.59694555,455639.807137755 4973608.4661572,455638.377942947
>> 4973614.49593153,455636.97649546 4973621.32268911,455634.084325749
>> 4973637.51733042,455631.585960851 4973653.17474669,455630.344123986
>> 4973661.50140289,455629.696234567 4973665.93866226,455629.696234567
>> 4973665.93866226,455628.383269606 4973675.5239203,455626.235378731
>> 4973693.34686891,455624.997527166 4973707.75141773,455625.052806357
>> 4973722.19487999,455626.239816571 4973728.34327406,455630.963831745
>> 4973736.33081102,455634.327007261 4973739.18140708))',32631) AS pg)
>> AS sq;
>>
>>  intersects | distance | within | isvalid | isvalid
>> ------------+----------+--------+---------+---------
>>  t          |        0 | f      | t       | t
>> (1 row)
>>
>> !!!
>>
>> --
>> Arnaud
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>
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```