common: add Python utility for reading DMAP files (#1059)

scripts/python/MvsReadDMAP.py

@@ -0,0 +1,42 @@
+'''
+Example usage of MvsUtils.py for exporting dmap file content.
+
+usage: MvsReadDMAP.py [-h] [--input INPUT] [--output OUTPUT]
+'''
+
+from argparse import ArgumentParser
+from concurrent.futures import ProcessPoolExecutor
+from glob import glob
+from MvsUtils import loadDMAP
+import numpy as np
+import os
+import pyvips
+
+def exportDMAPContent(dmap_path):
+  dmap = loadDMAP(dmap_path)
+
+  basename = os.path.splitext(os.path.basename(dmap['file_name']))[0]
+
+  pyvips.Image.new_from_array(np.uint8(dmap['depth_map'] * (1 / dmap['depth_max']) * 255)).write_to_file('%s_depth_map.png' % basename)
+  if dmap['has_normal']:
+    pyvips.Image.new_from_array(np.uint8((dmap['normal_map'] @ -dmap['R'] + 1) * 0.5 * 255)).write_to_file('%s_normal_map.png' % basename)
+  if dmap['has_conf']:
+    pyvips.Image.new_from_array(np.uint8(dmap['confidence_map'] * (1 / dmap['confidence_map'].max()) * 255)).write_to_file('%s_confidence_map.png' % basename)
+
+def main():
+  parser = ArgumentParser()
+  parser.add_argument('-i', '--input', type=str, required=True, help='path to the depth map directory')
+  parser.add_argument('-t', '--threads', type=int, default=int(os.cpu_count() * 0.5) - 1, help='number of parallel computations')
+  parser.add_argument('-o', '--output', type=str, required=True, help='path to the output directory')
+  args = parser.parse_args()
+
+  dmap_paths = glob(os.path.join(args.input, '*.dmap'))
+
+  os.makedirs(args.output, exist_ok = True)
+  os.chdir(args.output)
+
+  with ProcessPoolExecutor(max_workers=args.threads) as executor:
+    executor.map(exportDMAPContent, dmap_paths)
+
+if __name__ == '__main__':
+  main()

scripts/python/MvsUtils.py

@@ -0,0 +1,67 @@
+'''
+OpenMVS python utilities.
+
+E.g., from MvsUtils import loadDMAP
+'''
+
+import numpy as np
+
+def loadDMAP(dmap_path):
+  with open(dmap_path, 'rb') as dmap:
+    file_type = dmap.read(2).decode()
+    content_type = np.frombuffer(dmap.read(1), dtype=np.dtype('B'))
+    reserve = np.frombuffer(dmap.read(1), dtype=np.dtype('B'))
+
+    has_depth = content_type > 0
+    has_normal = content_type in [3, 7, 11, 15]
+    has_conf = content_type in [5, 7, 13, 15]
+    has_views = content_type in [9, 11, 13, 15]
+
+    image_width, image_height = np.frombuffer(dmap.read(8), dtype=np.dtype('I'))
+    depth_width, depth_height = np.frombuffer(dmap.read(8), dtype=np.dtype('I'))
+
+    if (file_type != 'DR' or has_depth == False or depth_width <= 0 or depth_height <= 0 or image_width < depth_width or image_height < depth_height):
+      print('error: opening file \'%s\' for reading depth-data' % dmap_path)
+      return None
+
+    depth_min, depth_max = np.frombuffer(dmap.read(8), dtype=np.dtype('f'))
+
+    file_name_length = np.frombuffer(dmap.read(2), dtype=np.dtype('H'))[0]
+    file_name = dmap.read(file_name_length).decode()
+
+    view_ids_length = np.frombuffer(dmap.read(4), dtype=np.dtype('I'))[0]
+    reference_view_id, *neighbor_view_ids = np.frombuffer(dmap.read(4 * view_ids_length), dtype=np.dtype('I'))
+
+    K = np.frombuffer(dmap.read(72), dtype=np.dtype('d')).reshape(3, 3)
+    R = np.frombuffer(dmap.read(72), dtype=np.dtype('d')).reshape(3, 3)
+    C = np.frombuffer(dmap.read(24), dtype=np.dtype('d'))
+
+    depth_length = depth_width * depth_height
+    depth_map = np.frombuffer(dmap.read(4 * depth_length), dtype=np.dtype('f')).reshape(depth_height, depth_width)
+    normal_map = np.frombuffer(dmap.read(4 * depth_length * 3), dtype=np.dtype('f')).reshape(depth_height, depth_width, 3) if has_normal else np.asarray([])
+    confidence_map = np.frombuffer(dmap.read(4 * depth_length), dtype=np.dtype('f')).reshape(depth_height, depth_width) if has_conf else np.asarray([])
+    views_map = np.frombuffer(dmap.read(depth_length * 4), dtype=np.dtype('B')).reshape(depth_height, depth_width, 4) if has_views else np.asarray([])
+
+  data = {
+    'has_normal': has_normal,
+    'has_conf': has_conf,
+    'has_views': has_views,
+    'image_width': image_width,
+    'image_height': image_height,
+    'depth_width': depth_width,
+    'depth_height': depth_height,
+    'depth_min': depth_min,
+    'depth_max': depth_max,
+    'file_name': file_name,
+    'reference_view_id': reference_view_id,
+    'neighbor_view_ids': neighbor_view_ids,
+    'K': K,
+    'R': R,
+    'C': C,
+    'depth_map': depth_map,
+    'normal_map': normal_map,
+    'confidence_map': confidence_map,
+    'views_map': views_map
+  }
+
+  return data