update

py/snap_merge.py

@@ -0,0 +1,80 @@
+'''20240820: merge the bands of input images (of which there are N) together into an output.
+SNAP "beam/dimap" format assumed
+'''
+import os
+import sys
+import subprocess
+import xml.etree.ElementTree as ET
+
+def get_band_names(dimap_file):
+    # Extracts band names from a BEAM/DIMAP XML file.
+    tree = ET.parse(dimap_file)
+    root = tree.getroot()
+
+    # Find all bands
+    bands = []
+    for band in root.findall(".//Band"):
+        band_name = band.get("name")
+        bands.append(band_name)
+
+    return bands
+
+def create_band_math_expression(band_lists):
+    # Create an expression for band math. This example adds bands from multiple images.
+    expressions = []
+    num_bands = len(band_lists[0])
+    for i in range(num_bands):
+        terms = [f'B{i+1}(source{j+1})' for j in range(len(band_lists))]
+        # Example operation: addition of corresponding bands
+        expressions.append(' + '.join(terms))
+    return ' '.join(expressions)
+
+def main():
+    # File paths
+    input_images = ['image1.dim', 'image2.dim', 'image3.dim']  # Add more images as needed
+    output_image = 'output_image.tif'
+
+    # Paths to the DIMAP XML files
+    xml_images = [img.replace('.dim', '.xml') for img in input_images]
+
+    # Check if all XML files exist
+    for xml_file in xml_images:
+        if not os.path.exists(xml_file):
+            print(f"Error: DIMAP XML file {xml_file} not found.")
+            return
+
+    # Get band names
+    band_lists = []
+    for xml_file in xml_images:
+        bands = get_band_names(xml_file)
+        band_lists.append(bands)
+
+    # Verify that all images have the same number of bands
+    num_bands = len(band_lists[0])
+    if not all(len(bands) == num_bands for bands in band_lists):
+        print("Error: The number of bands in the images does not match.")
+        return
+
+    # Create band math expression
+    band_math_expression = create_band_math_expression(band_lists)
+
+    # Construct the GPT command
+    sources = ' '.join(f'-Ssource{i+1}={img}' for i, img in enumerate(input_images))
+    gpt_command = (
+        f'gpt BandMath {sources} '
+        f'-Pexpression="{band_math_expression}" -t {output_image}'
+    )
+
+    # Print the GPT command to verify
+    print(f'Generated GPT Command: {gpt_command}')
+
+    # Execute the GPT command
+    try:
+        subprocess.run(gpt_command, shell=True, check=True)
+        print(f'Successfully executed: {gpt_command}')
+    except subprocess.CalledProcessError as e:
+        print(f'Error occurred: {e}')
+
+if __name__ == '__main__':
+    main()
+