added srtm1_to_srtm3.py

srtm1_to_srtm3.py

@@ -0,0 +1,93 @@
+#!/usr/bin/env python3
+'''
+resample SRTM1 data to SRTM3
+'''
+
+import os
+import zipfile
+import numpy as np
+import rasterio
+import argparse
+from scipy import interpolate
+from concurrent.futures import ThreadPoolExecutor
+
+def resample_data(data, new_shape):
+    """
+    Resample the data array to the new shape using mean pooling.
+
+    Parameters:
+        data (numpy.array): The original data array.
+        new_shape (tuple): The shape of the new resampled array.
+
+    Returns:
+        numpy.array: The resampled data array.
+    """
+    old_height, old_width = data.shape
+    new_height, new_width = new_shape
+
+    x = np.linspace(0, 1, data.shape[0])
+    y = np.linspace(0, 1, data.shape[1])
+    f = interpolate.interp2d(y, x, data, kind='cubic')
+
+    x2 = np.linspace(0, 1, new_width)
+    y2 = np.linspace(0, 1, new_height)
+    resampled = f(y2, x2)
+
+    return resampled.astype(data.dtype)
+
+def process_hgt_file(filepath, output_folder):
+    with zipfile.ZipFile(filepath, 'r') as z:
+        z.extractall(output_folder)
+
+    filename = os.path.basename(filepath).replace('.zip', '')
+    file_path = os.path.join(output_folder, filename)
+
+    tmp_out = f"SRTM3_tmp_{filename}"
+    if not os.path.exists(file_path):
+        print("Expected %s to exist - skipping" % file_path)
+        return
+    with rasterio.open(file_path) as src:
+        data = src.read(1)
+        new_data = resample_data(data, (1201, 1201))  # SRTM3 resolution is 1201x1201 for 3 arc seconds
+        new_data = new_data.byteswap(inplace=True)
+
+        new_file_path = os.path.join(output_folder, tmp_out)
+        new_data.tofile(new_file_path)
+
+    os.remove(file_path)  # Clean up the extracted file
+
+    with zipfile.ZipFile(new_file_path + '.zip', 'w', compression=zipfile.ZIP_DEFLATED, compresslevel=9) as zf:
+        zf.write(new_file_path, arcname=tmp_out)
+
+    os.remove(new_file_path)  # Clean up the uncompressed new HGT file
+    os.rename(os.path.join(output_folder,tmp_out + ".zip"), file_path + ".zip")
+
+    print(f"Processed and resampled {filename} to SRTM3 resolution.")
+
+def process_directory(input_folder, output_folder, max_workers, overwrite):
+    with ThreadPoolExecutor(max_workers=max_workers) as executor:
+        futures = []
+        for filename in os.listdir(input_folder):
+            if filename.endswith(".hgt.zip"):
+                if not overwrite and os.path.exists(os.path.join(output_folder, filename)):
+                    print("Skipping existing file %s" % os.path.join(output_folder, filename))
+                    continue
+                futures.append(executor.submit(process_hgt_file, os.path.join(input_folder, filename), output_folder))
+        for future in futures:
+            future.result()
+
+def main():
+    parser = argparse.ArgumentParser(description="Convert SRTM1 HGT files to SRTM3 resolution with optional parallel processing.")
+    parser.add_argument("input_folder", type=str, help="Directory containing SRTM1 HGT files")
+    parser.add_argument("output_folder", type=str, help="Directory to save converted SRTM3 files")
+    parser.add_argument("--parallel", type=int, default=1, help="Specify the number of threads to use for parallel processing")
+    parser.add_argument("--overwrite", action='store_true', help="overwrite existing files")
+    args = parser.parse_args()
+
+    if not os.path.exists(args.output_folder):
+        os.makedirs(args.output_folder)
+
+    process_directory(args.input_folder, args.output_folder, args.parallel, args.overwrite)
+
+if __name__ == "__main__":
+    main()