Riccardo riccardopani at hotmail.com
Thu Apr 27 03:06:54 PDT 2023
I have shape file already created for a standard delivery.
The geometry type of this shape file is “Polygon” and I have to change it into
“Multipolygon”.
Is it possible? And how can I change this property in a shape file already
created without creating a new one?
Hi Riccardo,
if with "shape file" you are referring to the ESRI Shapefile format,
then, as you can read in the "ESRI Shapefile Technical Description" [1],
there is only one type of polygon layer (apart from the M and Z+M
variants) in the ESRI Shapefile format: it is called Polygon in the
format nomenclature and it can stores natively both multi-part and
single-part (which are actually multipart with only 1 part) geometries.
An ESRI Shapefile Polygon layer is imported in QGIS (at least, for
recent versions) as a "Polygon (MultiPolygon)" layer, i.e. a
MultiPolygon layer, even if it does not contains any feature or if only
contains geometries with only 1 part.
In QGIS, any geometry contained in an ESRI Shapefile Polygon layer is
considered a MultiPolygon geometry: if it has only 1 part, it will be a
MultiPolygon geometry with only one part; if it has more then 1 part, it
will be a MultiPolygon with more than 1 part.
Is your "shape layer" an ESRI Shapefile layer? If yes, could you better
explain why do you think the geometry type of this "shape file" is (non
Multi) "Polygon". If not, could you please name the format of the layer?
Best regards.
Andrea Giudiceandrea
[1]
https://www.esri.com/content/dam/esrisites/sitecore-archive/Files/Pdfs/library/whitepapers/pdfs/shapefile.pdf#page=12
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