[OSGeo Africa] QGIS Raster Clipping Issue

Hanlie Pretorius hanlie.pretorius at gmail.com
Wed Sep 3 23:06:37 PDT 2014


Hi Adarsh,

A raster always has to have a rectangular shape, so when you clip a
raster to a vector layer, it actually clips it to the bounding box of
the vector.

The blue area you are seeing will probably have 0 as their pixel
values, so you can prevent them from displaying by setting the colour
for the value 0 to white in the Style page of the Layer properties.

The blue area may also be the 'no data' area of the raster and you can
find out its value in the Metadata section of the Layer properties and
add that as a Value in the Style section and set its colour to white.

Regards
Hanlie

> Date: Wed, 3 Sep 2014 14:39:47 -0700
> From: Adarsh Sharma <adarsh.1989 at yahoo.com>
> To: Africa local chapter discussions <africa at lists.osgeo.org>
> Subject: [OSGeo Africa] QGIS Raster Clipping Issue
>
> Hi guys,
>
> I downloaded BIOCLIM/WORLCLIM data in order to complete the MAXENT modelling
> for invasives. I have also downloaded vector boundary data for local
> municipalities.
>
> Using QGIS, I clipped the raster image against the vector file which is at
> local municipality level so that I only focus on the area of my study. The
> clip was successful however there seems to be some unwanted blue block
> around the vector.
>
> Please see the attached image below if there is uncertainty with my
> explanation. Note the blue area around the vector. Can someone please assist
> me with getting rid of the blue block as seen in the attached screenshot
> below?
>
> Kind Regards,
> Adarsh
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