I have a Shapefile with Polygon features representing the world's land areas (continents, islands).
Is it possible to invert these, and get a geometry that represents the world's oceans and seas?
So the original land Polygons need to become rings in a single global Polygon that covers the planet.
Basically, I'm looking for something like Select > Inverse in Photoshop.
I am using QGIS.
Best Answer
You can do this using the following steps:
1- In QGIS go to
Vector > Research Tools > Polygon From Layer Extent
. Use the World's Land area as Input File. Choose the Desired name for the output file name of extent layer. This will create a new vector layer covering the Whole Land area.2- Use
Geoprocessing Tools > Difference
: Use the extent layer created in step one as input file and world's land area as difference file. Then You will get an opposite shapefile which represents the ocean.