[postgis-users] St_Area to acres

[Birgit Laggner]

I was looking at spatialreference.org <http://spatialreference.org>, 
too, and did find EPSG 102686, which has US-foot as projection unit and 
is meant for the same region as 26986...

Regards,

Birgit.

Am 10.07.2012 15:26, schrieb Nathan Gerber:
> In looking at EPSG:26986 on spatialreference.org 
> <http://spatialreference.org> ( 
> http://spatialreference.org/ref/epsg/26986/ ) it appears that the 
> projection's native units are meters rather than feet. If you divide 
> by 4046.85642 (number of square meters in an acre) your acreage 
> numbers will come out much closer than they are at present but will 
> still be a bit off.
> --
> Nathan Gerber
>
>
> On Mon, Jul 9, 2012 at 11:44 PM, Daniel Cole 
> <daniel at southernsolutionsms.com 
> <mailto:daniel at southernsolutionsms.com>> wrote:
>
>     I am using the code below:
>
>     *Select name, acreage, ST_Area(ST_Transform(geom, 26986))/43560 as
>     acres from ss.fields*
>
>     and getting these results.
>
>
>     name 	acreage 	acres
>     H 01 	
>     15.79
>     	
>     1.50398045317257
>     H 02 	
>     29.02
>     	
>     2.76480120804097
>     H 03 	
>     31.95
>     	
>     3.04337512685165
>     H 04 	
>     34.71
>     	
>     3.30710750534269
>     H 05 	
>     111.6
>     	
>     10.6322788992474
>
>
>
>
>     I have another program where I am importing the acreage data from
>     and I just wanted it to match up in postgis well in case I ever
>     wanted to calculate it myself.  It seems that I am almost there,
>     but I am a decimal off and I can't understand that.
>
>     Also I am not very familiar with the 26986, but I used it because
>     I saw it used for sqare feet somewhere else.  Should I be using
>     anything else?
>
>     Thanks,
>
>     DC
>
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