[Qgis-developer] Calculating acreage in 2.2

Randal Hale rjhale at northrivergeographic.com
Thu Feb 27 10:48:51 PST 2014


I'm going to plead insanity. I'm having the most inconsistent 
"calculating" day ever. I'm going for a walk and then try this again. In 
some instances things are off as described below. In others I get the 
correct results. This happened yesterday and today. In others it works 
fine. I built a grid and in some cases got the normal square footage - 
in others it was off. In all cases I've only used tools within QGIS.

Below is the data. I open it in QGIS, edit, and use the formula $area / 
43560. Projection is EPSG:2274 . I can't make this calculate correctly 
in my OSGEO install of QGIS 2.2. I do this on Ubuntu 12.04 QGIS 2.2 and 
it comes out right.

location is here to the data:
/northrivergeographic.com/documents/eshleman-022714.zip

Sorry if I'm unnecessarily causing you guys distress. I do appreciate 
the work you all are doing - 2.2 is an excellent piece of software. Even 
if I have to confirm I want to remove data from the view (ha).

randy

-----------------
Randal Hale, GISP
North River Geographic Systems, Inc
http://www.northrivergeographic.com
423.653.3611 rjhale at northrivergeographic.com
twitter:rjhale
http://about.me/rjhale

On 02/27/2014 12:00 PM, Randal Hale wrote:
> I think I may have found a bug....or I'm just slightly confused.
>
> I'm working on a client job (digitizing forestry stands) and I need to 
> calculate acres of the final area. The data I'm working with is in 
> EPSG:2274. So I create a field that is decimal (width 20, precision 5) 
> and in the field calculator I use $area/43560 - (there are 43560 
> square feet in an acre). My result is one decimal off - instead of 
> 195.30 acres I have 19.53 Acres. I've done this enough to where I'm 
> questioning every button push. If I divide by 4356 I get the correct 
> number. I'm currently doing this in Windows 7 OSGEO install QGIS 2.2.
>
> Anyway - can someone tell me I'm crazy...or not crazy. Projections are 
> set correctly...cat has remained off the keyboard etc.
>
> Randy
>



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