[postgis-users] st_area and 0.001953125

Thu Apr 15 02:17:55 PDT 2010

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.
>>
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>   

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  Dipl.-Geogr. Marc Jansen
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