crop mbtiles to another see desc

crop_mbtile_to_mbtile.py

import sqlite3
import sys
import shutil

if len(sys.argv) != 4:
    print 'usage: crop_mbtile_to_mbtile.py <input_mbtiles file> <reference_mbtiles file> <output_mbtiles file>'
    sys.exit(0)

shutil.copyfile(sys.argv[2], sys.argv[3])
conn_input_mbtiles = sqlite3.connect(sys.argv[1])
conn_reference_mbtiles = sqlite3.connect(sys.argv[2])
conn_output_mbtiles = sqlite3.connect(sys.argv[3])

cursor_input = conn_input_mbtiles.cursor()
cursor_reference = conn_reference_mbtiles.cursor()
cursor_output = conn_output_mbtiles.cursor()

cursor_reference.execute('SELECT tile_row, tile_column, zoom_level, tile_id FROM map WHERE tile_id IS NOT NULL')
reference_row = cursor_reference.fetchone()
while reference_row != None:
    tile_row = reference_row[0]
    tile_column = reference_row[1]
    zoom_level = reference_row[2]
    tile_id = reference_row[3]

    cursor_input.execute(
            '''SELECT tile_row, tile_column, zoom_level, tile_id FROM map WHERE
                tile_row = ? AND tile_column = ? AND zoom_level = ?''',
            (tile_row,tile_column,zoom_level)
    )
    input_row = cursor_input.fetchone()
    if input_row == None:
        #note, this may create a dangling pointer ?
        cursor_output.execute(
            '''DELETE FROM map WHERE tile_row = ? AND tile_column = ? AND zoom_level = ?''',
            (tile_row,tile_column,zoom_level)
        )
    else:
        input_tile_id = input_row[3]
        input_image_data = conn_input_mbtiles.cursor().execute(
            'SELECT tile_data FROM images WHERE tile_id=?',(input_tile_id,)
        ).fetchone()[0]
        cursor_output.execute('UPDATE images SET tile_data = ? WHERE tile_id = ?',
                (input_image_data,tile_id)
        )
        #HACK, incomplete implementation, leaves some grids behind
        cursor_output.execute(
            'UPDATE map SET grid_id = NULL WHERE tile_row = ? AND tile_column = ? AND zoom_level = ?',
            (tile_row, tile_column, zoom_level)
        )


    reference_row = cursor_reference.fetchone()

#HACK, incomplete implementation, should transfer utfgrids
cursor_output.execute('UPDATE map SET grid_id = NULL WHERE 1=1')
cursor_output.execute('DELETE FROM grid_key WHERE 1=1')
cursor_output.execute('DELETE FROM keymap WHERE 1=1')
cursor_output.execute('DELETE FROM grid_utfgrid WHERE 1=1')

#should be immediate
conn_output_mbtiles.commit()
cursor_output.execute('VACUUM')
conn_input_mbtiles.close()
conn_reference_mbtiles.close()
conn_output_mbtiles.close()

desc

crop mbtile to another

I needed to generate a large amount of terrain tiles which covered a very detailed zoom level, this creates a gigantic mbtiles file, most of which is for areas that I don't care about.


This script takes an input, in this case the terrain tiles, and a reference set of tiles and limits the input to a subset of the reference.


Should probably build in some tolerances, especially because this is used for background imagery
Also utfgrids get nuked