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binarymason/get_zoom.py

Created October 27, 2019 12:12
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  1. binarymason created this gist Oct 27, 2019.
    29 changes: 29 additions & 0 deletions get_zoom.py
    View file
    Original file line number Diff line number Diff line change
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    import math
    import sys

    import rasterio
    from rasterio.warp import (calculate_default_transform, transform)


    CHUNK_SIZE = 256


    def get_zoom(input, dst_crs="EPSG:3857"):
    with rasterio.drivers():
    with rasterio.open(input) as src:
    # Compute the geographic bounding box of the dataset.
    (west, east), (south, north) = transform(
    src.crs, "EPSG:4326", src.bounds[::2], src.bounds[1::2])

    affine, _, _ = calculate_default_transform(src.crs, dst_crs,
    src.width, src.height, *src.bounds, resolution=None)

    # grab the lowest resolution dimension
    resolution = max(abs(affine[0]), abs(affine[4]))

    return int(round(math.log((2 * math.pi * 6378137) /
    (resolution * CHUNK_SIZE)) / math.log(2)))


    if __name__ == "__main__":
    print(get_zoom(sys.argv[1]))