[Geopackage] Query on gpkg_tile_matrix - matrix_width and matrix_height

Burken, David DBurken at Radiantblue.com
Tue Jun 2 10:51:11 EDT 2015


Jenifer,

I disagree with this:
There must be a tile at row: 0, column: 0

Given: The GeoPackage spec explicitely allows sparse tile matrices.

Dave

On 06/02/2015 10:10 AM, Cochran, Jenifer wrote:

Good Morning Brad,


                The WhiteHorse GeoPackage on the OGC website is out of date and the matrix_width and matrix_height are incorrect.  Here is a link<https://drive.google.com/file/d/0ByvLbbvwoxUjREhlbGZyWVpNeG8/view?usp=sharing> to the updated WhiteHorse GeoPackage that has the correct information.



There must be an agreement between the tiles present, and the bounding box which will ultimately determine the matrix_height and matrix_width.   There ought to be one tile in each of the minimal and maximal rows and columns(There must be a tile at row: 0, column: 0, row: (matrix_height - 1), and column: (matrix_width -1)).  This must hold true at any of the zoom levels.  If this doesn't hold true then the bounding box doesn't represent the minimum bounds of the data.



The data must also comply with the following equations: pixel_x_size = Bounding Box width  * matrix_width  * tile_width

                                                                                                                   pixel_y_size = Bounding Box height * matrix_height * tile_height



Hopefully this clears the confusion on what the matrix_width and matrix_height represent.



Very Respectfully,
Jenifer Cochran


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