[gdal-dev] efficient querying of land and depth areas

[Yilmaz Arslanoglu]

Hello everybody;

I am using the OGR library to extract depth and land areas from
an ENC file (S-57 format).

What I want to do is to query whether a given point is on land
or is on a depth area. For this purpose, I have to call OGRGeometry::Intersects
or OGRGeometry::Contains functions for every polygon feature on one of
these layers.
(similarly, setting the point by  SetSpatialFilter on one of these
layers also does the job)

I tried these and they work quite OK, but unfortunately quite
inefficient at the same time.
Is there anybody who can offer any tips or references about efficient querying?

Best regards,
Yilmaz