36 lines
1.2 KiB
Python
36 lines
1.2 KiB
Python
from rasterio import Affine
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import math
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def deg2num(lat_deg, lon_deg, zoom):
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lat_rad = math.radians(lat_deg)
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n = 2.0 ** zoom
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xtile = int((lon_deg + 180.0) / 360.0 * n)
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ytile = int((1.0 - math.asinh(math.tan(lat_rad)) / math.pi) / 2.0 * n)
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return xtile, ytile
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def calculate_transform(args, min_col, max_col, min_row, max_row):
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# Constants for Web Mercator (EPSG:3857)
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tile_size_in_pixels = 256
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earth_circumference = 40075016.686 # in meters
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# Calculate the size of a tile in meters at the given zoom level
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tile_size_in_meters = earth_circumference / (2 ** args.zoom)
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# Calculate the geographic coordinates of the bounding box
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min_x = min_col * tile_size_in_meters
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max_x = (max_col + 1) * tile_size_in_meters
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min_y = (2 ** args.zoom - max_row - 1) * tile_size_in_meters
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max_y = (2 ** args.zoom - min_row) * tile_size_in_meters
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# Calculate the pixel size in x and y directions
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pixel_size_x = tile_size_in_meters / tile_size_in_pixels
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pixel_size_y = tile_size_in_meters / tile_size_in_pixels
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# Define the transformation
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transform = Affine.translation(min_x, min_y) * Affine.scale(pixel_size_x, -pixel_size_y)
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return transform
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