[Geopackage] Query on gpkg_tile_matrix - matrix_width and matrix_height
even.rouault at spatialys.com
Wed Jun 3 05:55:20 EDT 2015
Le mercredi 03 juin 2015 11:41:53, Brad Hards a écrit :
> On Wed, 3 Jun 2015 09:58:39 AM Pepijn Van Eeckhoudt wrote:
> > Yes, that’s the intended usage. gpkg_tile_matrix_set and gpkg_tile_matrix
> > define the grid/matrix/areas where tiles are located. This is orthogonal
> > to presence of data in the user data table.
> > The misleading part in the spec is the use of the word ‘minimum bounding
> > rectangle’. That should probably be removed, but that’s something for the
> > SWG to tackle.
> > If you need to determine the MBR for actually present data you should do
> > a SQL query to select minimum and maximum tile_row and tile_column from
> > the user data table.
(and if the bounding box in gpkg_contents is set, it is generally a better
hint for the useful bounding box)
> > Note that this is identical to WMTS. gpkg_tile_matrix_set and
> > gpkg_tile_matrix are equivalent to TileMatrixSet and TileMatrix in WMTS.
> > In WMTS you would use TileMatrixLimits to indicate a sub region of the
> > entire tile structure that actually contains data. GeoPackage doesn’t
> > have this, but you can achieve a similar effect using the SQL query
> > above or the extent in gpkg_contents.
> OK. I tried a WMTS client implementation once. I'd rather not think about
> it again :-)
For the record, I'm working on a GDAL WMTS client that should land into GDAL
trunk (2.1dev now) soon.
> And I think the corrected "Whitehorse" sample reflects that. So I'm happy.
I'm noticying strange colours (greenish and pinkish) in
2015_05_05_Whitehorse_3857.gpkg whereas they looked OK in the original
ERDC_Whitehorse_GeoPackage.gpkg . Not sure if this is intended or not. It
seems that the JPEG tiles in the updated package use the uncommon colorspace
CMYK. I've extracted such a tile and displayed it with various readers and I
still have the same strange colours
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