[Qgis-user] Checking what is the scale/resolution of vector layer

[Carlos Cerdán]

.... However, in this case, I think you can estimate a (maxima) scale 
based at the minimo detail that you can finding in the vector layer and 
in the permitted error.

The permitted error it's based in the average minimo detail that human 
eye can perceive. It's estimated in 0.2 mm, so you can use this relation:

      1                  lenght in papper
----------    =     -----------------------
scale                length in reality

Lenght in papper is 0.2 mm. If your permitted error is 10 metres (10000 
mm),  then:

scale = 10000 / 0.2 = 50000

This is in theory. Reality is that error can be (is in fact) greater 
depending on method for get the vector layer. For example, a lines layer 
from a navigator GPS has an error of .... 20 m, then this layer has a 
maxima util scale of 1 : 100 000. You can use for other minor scales (1: 
200 000 ; 1 250 000; etc) with good precission, but not for 1:50 000, or 
higher.

Good luck

Carlos Cerdán




El 10/08/13 05:10, Nick Hopton escribió:
> Luisa Peña wrote
>> Dear all,
>> I have a vector (in ESRI Shapefile) and I wanted to know what is its scale
>> of oproduction (1:1000 or 1:100000 or something) since I have no
>> associated
>> metada.
>> Thanks
>> Luisa
>>
>> _______________________________________________
>> Qgis-user mailing list
>> Qgis-user at .osgeo
>> http://lists.osgeo.org/mailman/listinfo/qgis-user
> Hi Luisa, shapefiles don't have a 'scale' as such, you can render them in
> QGIS at any scale that produces the result you are looking for, but it's for
> you to set the scale for the project. For example, a lot of the shapefiles I
> use render well at a scale of 1:25000 but in most cases I can also use them
> at scales of say 1:10000 or 1:50000.
>
> N.
>
>
>
> --
> View this message in context: http://osgeo-org.1560.x6.nabble.com/Checking-what-is-the-scale-resolution-of-vector-layer-tp5071761p5071829.html
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