On 03/17/2015 02:53 PM, Jukka Rahkonen wrote:
Hi,
Is is possible to use COORDS for all kind of geodata? Is it possible
to import data from PostGIS into COORDS
Not currently. A COORDs storage currently consists of two parts: raw OSM
data, and geometry tiles.
The first part stores unprocessed OSM data (ways, nodes, relations) and
array indices into these data files (mapping an OSM entity ID to that
entity's position in the data file). This part is specific to OSM, and
is necessary to allow for the (planned) application of OSM replication
diffs (e.g. when a way from a diff references an already existing node,
the position of that node has to be retrieved from these index files).
The second part of the COORDS storage stores the actual geometry tiles
used for data retrieval. They currently store serialized OSM ways. But
this storage format will likely change to store point, line and
multipolygon features with arbitrary attributes. This second geometry
tile storage is currently created from the first storage of unprocessed
data. So there are some dependencies on OSM data structures.
However, if there is sufficient need, one could write an adapter that
directly creates the geometry tiles directly from another data source
(e.g. from a PostGIS database) and bypasses the creation of the first
part. But that is not currently implemented or planned.
could it be possible to write a GDAL/OGR driver for COORDS?
I am not familiar with the exact interface that a GDAL/OGR driver would
need to implement, so I cannot give you a definite answer. The COORDS
Mapnik plugin (currently the only consumer of COORDS data storages) get
passed a query bounding box and optionally a list of geometry attribute
names that should be included in the reply. It then returns the geometry
features (currently only line strings or simple polygons) along with the
list of attributes for each feature. As long as the GDAL/OGR interface
is sufficiently similar to that of Mapnik (i.e. it also sends a query
bounding box, and expects attributed features to be returned), writing
such a driver should be possible.
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