Benoit,
Indeed OGR_L_GetExtent() will never fill the Z fields, since it has no
idea they are there. So a 3D specific function would be needed.
But in the case of GeoPackage, as many/most other formats, layer extent
metadata doesn't include the Z component either. The generic option is
to iterate over all features and use OGR_G_GetEnvelope3D() on their
geometry.
In the specific case of GeoPackage, you could also issue a
ExecuteSQL("SELECT MIN(ST_MinZ(geometry_column_name)),
MAX(ST_MaxZ(geometry_column_name)) FROM layer_name") which should be
faster on big layers
Even
Le 23/06/2023 à 11:14, B. De Mezzo a écrit :
Hi,
I was looking for a solution to retrieve a 3D extent (in my case from
a gpkg). Currently, the OGR_L_GetExtent function uses an OGREnvelope
and when I pass a OGREnvelope3D parameter, it does not fill the Z fields.
What should be the best approach to the minZ and maxZ for a layer?
Regards.
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