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Zoom Other Intervals

This extension allows the use of tile pyramids with zoom levels that are separated by something other than a power of 2. This can be useful for certain types of raster data as described in this blog post.

gpkg_extensions

Add a row to this table for each tile pyramid that does not have tile matrices separated by powers of two.

Column Value
table_name tile pyramid user data table name
column_name tile_data
extension_name gpkg_zoom_other
definition http://www.geopackage.org/spec120/#extension_zoom_other_intervals
scope read-write

gpkg_tile_matrix

When using this extension, the pixel_x_size and pixel_y_size can differ by arbitrary amounts. One approach is to have the pixel sizes for the highest zoom level match the native resolution of the raster data as closely as possible and for the next highest zoom level to have significantly higher pixel sizes, perhaps matching the pixel size of a tile matrix from a more commonly used tile matrix set. This maximizes image quality and reduces wasted space.