Add prepare_10m_sentinel_imagery.py script

Script to process Sentinel  2 10m imagery for general use.

sentinel2-image-processing/prepare_10m_sentinel_imagery.py

@@ -0,0 +1,167 @@
+#!/usr/bin/env python3
+
+"""
+This is a Python version of a bash script written by Rebecca Clarke https://gist.github.com/rebclarke/b9e55a3558be3ec76248c78379b67366
+"""
+
+import os
+import glob
+import shutil
+from osgeo import gdal
+import subprocess
+
+
+# user definated variables
+TILE_INDEX = "nz-150k-tile-index.shp"
+MIN = "800"
+MAX = "3000"
+CWD = "C:/Temp/image-processing/test"
+SENTINEL_IMAGE_DIR = "R10m"
+GDAL_DIR = "C:/Program Files/QGIS 3.34.4/apps/Python39/Scripts"
+
+
+def make_directories(dir_name):
+    """
+    Create directors for the various processed images to be saved into.
+    """
+    path = os.path.join(CWD, dir_name)
+    if os.path.exists(path):
+        shutil.rmtree(path)
+    os.mkdir(path)
+
+
+# make output directories
+make_directories("output")
+make_directories("output/merged")
+make_directories("output/rescaled")
+make_directories("output/nearblack")
+make_directories("output/reprojected")
+make_directories("output/tiled")
+
+
+path = os.path.join(CWD, SENTINEL_IMAGE_DIR)
+rgb_files = glob.glob("R10m/*B0[2-4]_10m.jp2")
+
+blue = rgb_files[0]
+green = rgb_files[1]
+red = rgb_files[2]
+
+gdal_merge_path = os.path.join(GDAL_DIR, "gdal_merge.py")
+
+merged_output = os.path.join(CWD, "output/merged", "merged.tif")
+translate_output = os.path.join(CWD, "output/rescaled", "rescaled.tif")
+nearblack_output = os.path.join(CWD, "output/nearblack", "nearblack.tif")
+reprojected_output = os.path.join(CWD, "output/reprojected", "reprojected.tif")
+tiled_output_dir = os.path.join(CWD, "output/tiled")
+vrt_output = os.path.join(CWD, "output", "overall.vrt")
+
+# merge the three R,G,B images together to create a single RGB image
+print("Merging image tiles into one RGB image")
+subprocess.run(
+    [
+        "python.exe",
+        gdal_merge_path,
+        "-separate",
+        "-co",
+        "PHOTOMETRIC=RGB",
+        "-o",
+        merged_output,
+        red,
+        green,
+        blue,
+    ]
+)
+
+# rescale the imagery to 8bit unsigned
+print("Rescaling to  8bit unsigned")
+subprocess.run(
+    [
+        "gdal_translate",
+        "-ot",
+        "Byte",
+        "-of",
+        "GTiff",
+        "-scale",
+        MIN,
+        MAX,
+        "1",
+        "255",
+        "-b",
+        "1",
+        "-b",
+        "2",
+        "-b",
+        "3",
+        "-co",
+        "compress=lzw",
+        merged_output,
+        translate_output,
+    ]
+)
+
+# run nearblack
+print("Running nearblack and setting alpha channel")
+subprocess.run(
+    [
+        "nearblack",
+        "-of",
+        "GTiff",
+        "-setalpha",
+        "-o",
+        nearblack_output,
+        translate_output,
+    ]
+)
+
+# reproject to NZTM 2000
+print("Reprojecting to NZTM 2000")
+subprocess.run(
+    [
+        "gdalwarp",
+        "-t_srs",
+        "EPSG:2193",
+        "-r",
+        "bilinear",
+        "-tr",
+        "10",
+        "-10",
+        "-co",
+        "compress=lzw",
+        nearblack_output,
+        reprojected_output,
+    ]
+)
+
+# mosaic into a single image
+print("Building VRT")
+subprocess.run(["gdalbuildvrt", vrt_output, reprojected_output])
+
+print("Tiling to Topo 50")
+ogr_info = subprocess.Popen(
+    ["ogrinfo", "-ro", "-al", TILE_INDEX], stdout=subprocess.PIPE
+)
+
+# tile into Topo50 sheet extents
+ogr_output = ogr_info.communicate()[0].decode("utf-8")
+for line in ogr_output.splitlines():
+    if "sheet_code" in line:
+        sheet_code = line[len(line) - 4 : len(line) - 0]
+        subprocess.run(
+            [
+                "gdalwarp",
+                vrt_output,
+                f"{tiled_output_dir}/{sheet_code}.tif",
+                "-cutline",
+                TILE_INDEX,
+                "-cwhere",
+                f"sheet_code = '{sheet_code}'",
+                "-tr",
+                "10",
+                "-10",
+                "-co",
+                "compress=lzw",
+                "-t_srs",
+                "EPSG:2193",
+                "-crop_to_cutline",
+            ]
+        )