[postgis-users] st_area and 0.001953125

Birgit Laggner birgit.laggner at vti.bund.de
Thu Apr 15 04:58:02 PDT 2010 

Hi Marc,

here my full versions list for all 3 servers:

"POSTGIS="1.3.6" GEOS="3.1.1-CAPI-1.6.0" PROJ="Rel. 4.6.1, 21 August
2008" USE_STATS"
"PostgreSQL 8.2.13 on x86_64-unknown-linux-gnu, compiled by GCC gcc
(SUSE Linux) 4.3.2 [gcc-4_3-branch revision 141291]"

"POSTGIS="1.3.6" GEOS="3.1.1-CAPI-1.6.0" PROJ="Rel. 4.7.1, 23 September
2009" USE_STATS (procs from 1.3.3 need upgrade)"
"PostgreSQL 8.2.15 on x86_64-unknown-linux-gnu, compiled by GCC gcc
(SUSE Linux) 4.4.1 [gcc-4_4-branch revision 150839]"

"POSTGIS="1.4.0" GEOS="3.2.0-CAPI-1.6.0" PROJ="Rel. 4.6.1, 21 August
2008" USE_STATS"
"PostgreSQL 8.4.2 on x86_64-unknown-linux-gnu, compiled by GCC gcc (SUSE
Linux) 4.4.1 [gcc-4_4-branch revision 150839], 64-bit"

I will try to upgrade my local postgis installation in order to verify
your guess (postgis version dependance).

Thanks again and regards,

Birgit.


On 15.04.2010 13:37, Marc Jansen wrote:
> Hi Birgit,
>
> I can confirm your results on
>
> POSTGIS="1.3.1" GEOS="2.2.3-CAPI-1.1.1" PROJ="Rel. 4.4.9, 29 Oct 2004"
> USE_STATS
>
> 0.001953125 or 0 for the given examples.
>
> I can only guess that it is some sort of silent change in between
> 1.4.0 and 1.4.1. Could that be? Do have the possibility to upgrade
> your Postgis installation? BTW which version of Postgresql are you using?
>
> The confirmed error is on "PostgreSQL 8.2.4 on x86_64-pc-linux-gnu,
> compiled by GCC cc (GCC) 4.1.2 20061115 (prerelease) (Debian
> 4.1.1-21)", the correct results are obtained from "PostgreSQL 8.4.2 on
> i486-pc-linux-gnu, compiled by GCC gcc-4.4.real (Ubuntu
> 4.4.1-4ubuntu8) 4.4.1, 32-bit" (selected using "SELECT version();")
>
> Regards,
> Marc
>
>
> Birgit Laggner wrote:
>> Hi Marc,
>>
>> your results look wonderful, but I don't know how you achieve them. Here
>> my results for your pgsql statement and the postgis_fullversion for the
>> 3 servers I tested the statement on:
>>
>> "POSTGIS="1.4.0" GEOS="3.2.0-CAPI-1.6.0" PROJ="Rel. 4.6.1, 21 August
>> 2008" USE_STATS"
>> 0.001953125
>> 0.001953125
>> 0.001953125
>> 0.001953125
>> 0
>> 0.001953125
>> 0
>> 0.001953125
>> 0.001953125
>> 0.001953125
>>
>>
>> "POSTGIS="1.3.6" GEOS="3.1.1-CAPI-1.6.0" PROJ="Rel. 4.6.1, 21 August
>> 2008" USE_STATS"
>> 0
>> 0.001953125
>> 0.001953125
>> 0.001953125
>> 0.001953125
>> 0.001953125
>> 0.001953125
>> 0.001953125
>> 0
>> 0.001953125
>>
>>
>>
>> "POSTGIS="1.3.6" GEOS="3.1.1-CAPI-1.6.0" PROJ="Rel. 4.7.1, 23 September
>> 2009" USE_STATS (procs from 1.3.3 need upgrade)"
>> 0
>> 0.001953125
>> 0.001953125
>> 0.001953125
>> 0.001953125
>> 0.001953125
>> 0.001953125
>> 0.001953125
>> 0
>> 0.001953125
>>
>>
>> Any suggestions why my results are so different from yours?
>>
>> Thanks and regards,
>>
>> Birgit.
>>
>>
>>
>>
>> On 15.04.2010 11:17, Marc Jansen wrote:
>>  
>>> Hi Birgit,
>>>
>>> I have different results here:
>>>
>>> http://osgeo.pastebin.com/dhPpqH9J
>>>
>>> Regards,
>>> Marc
>>>
>>>
>>>
>>> Birgit Laggner wrote:
>>>    
>>>> Yes, sure... Here some of my geometries with st_area=0.001953125
>>>> (1/2^9):
>>>>
>>>> "SRID=31467;POLYGON((3508395.5093 5910738.8973,3508505.2864
>>>> 5910690.8533,3508300.641 5910780.4164,3508395.5093 5910738.8973))"
>>>> "SRID=31467;POLYGON((3508395.5093 5949092.7294,3508333.8642
>>>> 5949090.138,3508411.1808 5949093.3882,3508395.5093 5949092.7294))"
>>>> "SRID=31467;POLYGON((3498246.2563 5815493.2389,3498246.2472
>>>> 5815493.1259,3498246.2094 5815493.1202,3498246.2563 5815493.2389))"
>>>> "SRID=31467;POLYGON((3539635.9601 5832797.6616,3539635.9574
>>>> 5832797.6613,3539635.9565 5832797.6851,3539635.9601 5832797.6616))"
>>>> "SRID=31467;POLYGON((3546842.9496103 5778962.75289926,3546842.9761781
>>>> 5778962.61321963,3546842.976 5778962.613,3546842.9496103
>>>> 5778962.75289926))"
>>>> "SRID=31467;POLYGON((3427425.5879 5841806.726,3427416.0171
>>>> 5841792.2466,3427416.01703247 5841792.24664866,3427425.5879
>>>> 5841806.726))"
>>>> "SRID=31467;POLYGON((3538420.34038636
>>>> 5912791.09822265,3538420.31141462
>>>> 5912790.97224757,3538420.3113 5912790.9723,3538420.34038636
>>>> 5912791.09822265))"
>>>> "SRID=31467;POLYGON((3577970.8916 5729534.987,3577827.5551
>>>> 5729621.0532,3577805.6282 5729634.2192,3577970.8916 5729534.987))"
>>>> "SRID=31467;POLYGON((3472882.79775403 5870816.50310222,3472882.7978
>>>> 5870816.5031,3472875.19541818 5870717.64922727,3472882.79775403
>>>> 5870816.50310222))"
>>>> "SRID=31467;POLYGON((3557563.34513562 5791040.4530635,3557563.44511383
>>>> 5791040.49625184,3557563.3452 5791040.4529,3557563.34513562
>>>> 5791040.4530635))"
>>>>
>>>> st_area=0.00390625 (1/2^8):
>>>>
>>>> "SRID=31467;POLYGON((3570365.59720136 5742710.02924098,3570358.1909
>>>> 5742719.6418,3570358.191599 5742719.64149272,3570365.59720136
>>>> 5742710.02924098))"
>>>> "SRID=31467;POLYGON((3561579.38938441 5905129.43679735,3561545.6658
>>>> 5905163.3222,3561522.09118149 5905187.00889311,3561545.6653
>>>> 5905163.3228,3561579.38938441 5905129.43679735))"
>>>> "SRID=31467;POLYGON((3552150.9548 5742650.4051,3552168.62992722
>>>> 5742646.68243639,3552168.6301 5742646.6818,3552150.9548
>>>> 5742650.4051))"
>>>> "SRID=31467;POLYGON((3561749.8571 5865749.873,3561799.5277
>>>> 5865766.3108,3561799.52805235 5865766.31075114,3561749.8571
>>>> 5865749.873))"
>>>> "SRID=31467;POLYGON((3473864.032 5873365.3502,3473872.3622
>>>> 5873371.4589,3473879.97516418 5873377.10501052,3473872.3622
>>>> 5873371.4584,3473864.032 5873365.3502))"
>>>> "SRID=31467;POLYGON((3560788.59448517 5748665.31989661,3560796.5561
>>>> 5748667.1403,3560807.5257 5748669.0521,3560796.5561
>>>> 5748667.1398,3560788.59448517 5748665.31989661))"
>>>> "SRID=31467;POLYGON((3456586.93009402 5872050.7320991,3456603.71148126
>>>> 5872024.70635152,3456586.9299 5872050.7319,3456586.93009402
>>>> 5872050.7320991))"
>>>> "SRID=31467;POLYGON((3573125.32168799 5906771.92751555,3573125.3215
>>>> 5906771.9274,3573112.75787677 5906796.71385397,3573112.7581
>>>> 5906796.7139,3573125.32168799 5906771.92751555))"
>>>> "SRID=31467;POLYGON((3575905.7401 5719920.9669,3575904.88200387
>>>> 5719873.25691506,3575904.882 5719873.2572,3575905.7401 5719920.9669))"
>>>> "SRID=31467;POLYGON((3547343.0802 5741914.6939,3547341.3108
>>>> 5741921.4379,3547339.1261 5741930.6872,3547336.9408
>>>> 5741937.6228,3547335.58835 5741941.09235,3547336.9408
>>>> 5741937.6233,3547339.1261 5741930.6877,3547341.3108
>>>> 5741921.4384,3547343.0802 5741914.6939))"
>>>>
>>>> st_area=0.0078125 (1/2^7):
>>>>
>>>> "SRID=31467;POLYGON((3650622.49435981 5875166.19247976,3650619.8317
>>>> 5875115.4098,3650622.4941 5875166.1925,3650622.49435981
>>>> 5875166.19247976))"
>>>> "SRID=31467;POLYGON((3568389.67127267 5851488.1421237,3568389.6712
>>>> 5851488.1422,3568495.5728 5851570.3678,3568389.67127267
>>>> 5851488.1421237))"
>>>> "SRID=31467;POLYGON((3571954.51978888 5753275.44491658,3571927.0019
>>>> 5753378.6038,3571954.5199 5753275.445,3571954.51978888
>>>> 5753275.44491658))"
>>>> "SRID=31467;POLYGON((3555658.1082 5728053.622,3555651.679
>>>> 5728050.4778,3555644.8351 5728048.1717,3555634.0498
>>>> 5728047.1242,3555644.8351 5728048.1723,3555651.679
>>>> 5728050.4783,3555658.1082 5728053.622))"
>>>> "SRID=31467;POLYGON((3555058.35805504 5715181.02070526,3555108.2704
>>>> 5715190.4028,3555058.3581 5715181.0204,3555058.35805504
>>>> 5715181.02070526))"
>>>> "SRID=31467;POLYGON((3395315.40197822 5840656.87971937,3395229.2098
>>>> 5840619.9673,3395315.4019 5840656.8799,3395315.40197822
>>>> 5840656.87971937))"
>>>> "SRID=31467;POLYGON((3573074.18310709 5740403.73582028,3573074.183
>>>> 5740403.7363,3573096.5482 5740407.9711,3573074.18310709
>>>> 5740403.73582028))"
>>>> "SRID=31467;POLYGON((3544884.936 5844897.712,3544851.31613268
>>>> 5844807.24085704,3544851.316 5844807.241,3544884.936 5844897.712))"
>>>> "SRID=31467;POLYGON((3576480.5538 5704180.1479,3576466.1052
>>>> 5704170.6652,3576450.375 5704162.5361,3576466.1052
>>>> 5704170.6657,3576480.5538 5704180.1479))"
>>>> "SRID=31467;POLYGON((3576450.375 5704162.5361,3576437.7542
>>>> 5704156.0998,3576421.8422 5704149.326,3576437.7542
>>>> 5704156.1003,3576450.375 5704162.5361))"
>>>>
>>>> Just a few examples... As I said, all of my areas are multiples of
>>>> 1/2^9...
>>>>
>>>> Regards,
>>>>
>>>> Birgit.
>>>>
>>>>
>>>>
>>>> On 13.04.2010 02:08, Greg Williamson wrote:
>>>>  
>>>>      
>>>>> What SRID(s) ? Could you give an example, perhaps ?
>>>>>
>>>>> Greg W.
>>>>>
>>>>>
>>>>>
>>>>> ----- Original Message ----
>>>>> From: Birgit Laggner <birgit.laggner at vti.bund.de>
>>>>> To: PostGIS Users Discussion <postgis-users at postgis.refractions.net>
>>>>> Sent: Mon, April 12, 2010 5:43:24 AM
>>>>> Subject: [postgis-users] st_area and 0.001953125
>>>>>
>>>>> Dear list,
>>>>>
>>>>> when I use st_area(), I always get multiples of 0.001953125 (1/2^9)
>>>>> as a
>>>>> result. Can anybody explain why?
>>>>>
>>>>> Thanks and regards,
>>>>>
>>>>> Birgit.
>>>>>
>>>>> _______________________________________________
>>>>> postgis-users mailing list
>>>>> postgis-users at postgis.refractions.net
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>>>>>
>>>>>
>>>>>
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>>>>>
>>>>>               
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>>>>         
>>>     
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