def process_tile(tile):
"""Process a single MBTiles tile
Parameters
----------
tile : mercantile.Tile
Returns
-------
tile : mercantile.Tile
The input tile.
bytes : bytearray
Image bytes corresponding to the tile.
"""
global base_kwds, resampling, src
# Get the bounds of the tile.
ulx, uly = mercantile.xy(
*mercantile.ul(tile.x, tile.y, tile.z))
lrx, lry = mercantile.xy(
*mercantile.ul(tile.x + 1, tile.y + 1, tile.z))
kwds = base_kwds.copy()
kwds['transform'] = transform_from_bounds(ulx, lry, lrx, uly,
kwds['width'], kwds['height'])
src_nodata = kwds.pop('src_nodata', None)
dst_nodata = kwds.pop('dst_nodata', None)
warnings.simplefilter('ignore')
with MemoryFile() as memfile:
with memfile.open(**kwds) as tmp:
# determine window of source raster corresponding to the tile
# image, with small buffer at edges
try:
west, south, east, north = transform_bounds(TILES_CRS, src.crs, ulx, lry, lrx, uly)
tile_window = window_from_bounds(west, south, east, north, transform=src.transform)
adjusted_tile_window = Window(
tile_window.col_off - 1, tile_window.row_off - 1,
tile_window.width + 2, tile_window.height + 2)
tile_window = adjusted_tile_window.round_offsets().round_shape()
# if no data in window, skip processing the tile
if not src.read_masks(1, window=tile_window).any():
return tile, None
except ValueError:
log.info("Tile %r will not be skipped, even if empty. This is harmless.", tile)
reproject(rasterio.band(src, tmp.indexes),
rasterio.band(tmp, tmp.indexes),
src_nodata=src_nodata,
dst_nodata=dst_nodata,
num_threads=1,
resampling=resampling)
return tile, memfile.read()
def __geo_transform__(self):
tfm = transform_from_bounds(*tuple(
e for e in chain(self.bounds, self.shape[2:0:-1])))
return AffineTransform(tfm, "EPSG:3857")
def process_tile(tile):
"""Process a single MBTiles tile
Parameters
----------
tile : mercantile.Tile
warp_options : Mapping
GDAL warp options as keyword arguments.
Returns
-------
tile : mercantile.Tile
The input tile.
bytes : bytearray
Image bytes corresponding to the tile.
"""
global base_kwds, resampling, filename, open_options, warp_options
with rasterio.open(filename, **open_options) as src:
# Get the bounds of the tile.
ulx, uly = mercantile.xy(*mercantile.ul(tile.x, tile.y, tile.z))
lrx, lry = mercantile.xy(*mercantile.ul(tile.x + 1, tile.y +
1, tile.z))
kwds = base_kwds.copy()
kwds["transform"] = transform_from_bounds(ulx, lry, lrx, uly,
kwds["width"],
kwds["height"])
src_nodata = kwds.pop("src_nodata", None)
dst_nodata = kwds.pop("dst_nodata", None)
warnings.simplefilter("ignore")
log.info("Reprojecting tile: tile=%r", tile)
with MemoryFile() as memfile:
with memfile.open(**kwds) as tmp:
# determine window of source raster corresponding to the tile
# image, with small buffer at edges
try:
west, south, east, north = transform_bounds(
TILES_CRS, src.crs, ulx, lry, lrx, uly)
tile_window = window_from_bounds(west,
south,
east,
north,
transform=src.transform)
adjusted_tile_window = Window(
tile_window.col_off - 1,
tile_window.row_off - 1,
tile_window.width + 2,
tile_window.height + 2,
)
tile_window = adjusted_tile_window.round_offsets(
).round_shape()
# if no data in window, skip processing the tile
if not src.read_masks(1, window=tile_window).any():
return tile, None
except ValueError:
log.info(
"Tile %r will not be skipped, even if empty. This is harmless.",
tile,
)
num_threads = int(warp_options.pop("num_threads", 2))
reproject(rasterio.band(src, tmp.indexes),
rasterio.band(tmp, tmp.indexes),
src_nodata=src_nodata,
dst_nodata=dst_nodata,
num_threads=num_threads,
resampling=resampling,
**warp_options)
return tile, memfile.read()