[Qgis-user] How to get rid of the rest of the World?

[Alex Mandel]

I usually make a new vector Layer. Then you can draw or use the
numerical vector editor to add a polygon. This polygon can then be used
as a clipping mask. Simply having a layer of a given extent isn't
enough, you have to have a polygon object in the layer.

As for why this isn't the way it already is, well QGIS is not ArcINFO or
GRASS where all data in one map are forced into the same projection and
you can set an extent property for the analysis. That's a different
concept of how to do GIS. One that is not very forgiving to projection
on the fly.

Thanks,
Alex

On 04/22/2014 07:24 AM, Simon Cropper wrote:
> Marcus,
> 
> I think what you are asking is can you just view the area that you are
> working on and have QGIS hide or filter out those feature not within the
> area of concern.
> 
> From my understanding is no. Well not exactly.
> 
> My understanding is that shapefiles will allways be processed regardless
> of whether they are visable. Feature may not be visible if they are
> outside the view or transparent.
> 
> You have two simple solutions to this problem.
> 
> 1. Create a routine to, or manually, clip all the shapefiles in your
> project based on a reference polygon bounded by your lat/longs.
> 2. Create a polygon covering the world and punch a hole through it,
> essentially creating a window bounded by your lat/longs. The polygon can
> be made opaque/white making it the same as the screen/page or
> semi-transparent, essentially fading the underlying features (nice
> effect in reports).
> 
> On 22/04/14 23:57, kmgkmgkmgkmg . wrote:
>> Hello everyone..
>>
>> I will be going on a little bit here now..
>>
>> Wonder how to create a clip/mask layer or do something to the same
>> effect?
>> More specifically, how to make a rectangular area of longitude and
>> latitude coordinates that enables to cut away the area not needed in
>> other layers?
>>
>> Since stuck with a quarter of the World or even the entire World in my
>> little project. This question is for shape file layers mostly, have not
>> gotten to the .tiff yet. They are not global though larger then needed.
>> So a universal solution for both types would be nice.
>>
>> Is there a python console command to do this?
>> Is there a plugin to do this?
>> Is there a online service to create such a layer?
>> Is it possible from within QGIS?
>>
>> Have tried the make a rectangle plugin, it cuts out zero features.
>> Also tried clipping with a layer of not the right shape and it says that
>> they do not have the right projection, even though it looks as they do,
>> and end up with a blank layer.
>>
>> Sure plenty people have this problem, though the forums do not have any
>> clear explanations as I found nothing that really explains, even youtube
>> got one but that is for regional borders.
>>
>> Is there some way of just knocking in the longitude and latitude to do
>> this?
>> Please assist. Do not get why this should be so difficult.
>>
>> Why does not QGIS ask first thing which area of the planet you wish to
>> work on a project? And then just filter out it automatically when you
>> load layer that include more than that? Perhaps this could be a feature
>> of a future release?
>>
>> With hopes for many answers and simple solutions. I repeat just want a
>> specified area that easily can be determined by longitude and latitude
>> coordinates.
>>
>> Yours hopefully..
>> Marcus
>>
>>
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> 
>