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replace struct.unpack calls in binary reads #4

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replace struct.unpack calls in binary reads #4

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60 changes: 38 additions & 22 deletions pycolmap/scene_manager.py
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@
#-------------------------------------------------------------------------------

class SceneManager:
INVALID_POINT3D = np.uint64(-1)
INVALID_POINT3D = np.int64(-1)

def __init__(self, colmap_results_folder, image_path=None):
self.folder = colmap_results_folder
Expand Down Expand Up @@ -83,6 +83,17 @@ def load(self):

#---------------------------------------------------------------------------

def read_next_bytes(self, fid, num_bytes, format_char_sequence, endian_character="<"):
"""Read and unpack the next bytes from a binary file.
:param fid:
:param num_bytes: Sum of combination of {2, 4, 8}, e.g. 2, 6, 16, 30, etc.
:param format_char_sequence: List of {c, e, f, d, h, H, i, I, l, L, q, Q}.
:param endian_character: Any of {@, =, <, >, !}
:return: Tuple of read and unpacked values.
"""
data = fid.read(num_bytes)
return struct.unpack(endian_character + format_char_sequence, data)

def load_cameras(self, input_file=None):
if input_file is None:
input_file = self.folder + 'cameras.bin'
Expand All @@ -98,13 +109,18 @@ def load_cameras(self, input_file=None):
def _load_cameras_bin(self, input_file):
self.cameras = OrderedDict()

with open(input_file, 'rb') as f:
num_cameras = struct.unpack('L', f.read(8))[0]

with open(input_file, 'rb') as fid:
num_cameras = self.read_next_bytes(fid, 8, "Q")[0]
for _ in range(num_cameras):
camera_id, camera_type, w, h = struct.unpack('IiLL', f.read(24))
camera_properties = self.read_next_bytes(
fid, num_bytes=24, format_char_sequence="iiQQ")
camera_id = camera_properties[0]
camera_type = camera_properties[1]
w = camera_properties[2]
h = camera_properties[3]
num_params = Camera.GetNumParams(camera_type)
params = struct.unpack('d' * num_params, f.read(8 * num_params))
params = self.read_next_bytes(fid, num_bytes=8*num_params,
format_char_sequence="d"*num_params)
self.cameras[camera_id] = Camera(camera_type, w, h, params)
self.last_camera_id = max(self.last_camera_id, camera_id)

Expand Down Expand Up @@ -139,27 +155,30 @@ def load_images(self, input_file=None):
def _load_images_bin(self, input_file):
self.images = OrderedDict()

with open(input_file, 'rb') as f:
num_images = struct.unpack('L', f.read(8))[0]
image_struct = struct.Struct('<I 4d 3d I')
with open(input_file, 'rb') as fid:
num_images = self.read_next_bytes(fid, 8, "Q")[0]
for _ in range(num_images):
data = image_struct.unpack(f.read(image_struct.size))
data = self.read_next_bytes(fid, num_bytes=64, format_char_sequence="idddddddi")
image_id = data[0]
q = Quaternion(np.array(data[1:5]))
t = np.array(data[5:8])
camera_id = data[8]
name = b''.join(c for c in iter(lambda: f.read(1), b'\x00')).decode()
name = ""
current_char = self.read_next_bytes(fid, 1, "c")[0]
while current_char != b"\x00": # look for the ASCII 0 entry
name += current_char.decode("utf-8")
current_char = self.read_next_bytes(fid, 1, "c")[0]

image = Image(name, camera_id, q, t)
num_points2D = struct.unpack('Q', f.read(8))[0]
num_points2D = self.read_next_bytes(fid, num_bytes=8,format_char_sequence="Q")[0]

# Optimized code below.
# Read all elements as double first, then convert to array, slice it
# into points2d and ids, and convert ids back to unsigned long longs
# ('Q'). This is significantly faster than using O(num_points2D) f.read
# calls, experiments show >7x improvements in 60 image model, 23s -> 3s.
points_array = array.array('d')
points_array.fromfile(f, 3 * num_points2D)
points_array.fromfile(fid, 3 * num_points2D)
points_elements = np.array(points_array).reshape((num_points2D, 3))
image.points2D = points_elements[:, :2]

Expand Down Expand Up @@ -227,8 +246,8 @@ def load_points3D(self, input_file=None):
raise IOError('no points3D file found')

def _load_points3D_bin(self, input_file):
with open(input_file, 'rb') as f:
num_points3D = struct.unpack('L', f.read(8))[0]
with open(input_file, 'rb') as fid:
num_points3D = self.read_next_bytes(fid, 8, "Q")[0]

self.points3D = np.empty((num_points3D, 3))
self.point3D_ids = np.empty(num_points3D, dtype=np.uint64)
Expand All @@ -237,22 +256,19 @@ def _load_points3D_bin(self, input_file):
self.point3D_id_to_images = dict()
self.point3D_errors = np.empty(num_points3D)

data_struct = struct.Struct('<Q 3d 3B d Q')

for i in range(num_points3D):
data = data_struct.unpack(f.read(data_struct.size))
data = self.read_next_bytes(fid, num_bytes=43, format_char_sequence="QdddBBBd")
self.point3D_ids[i] = data[0]
self.points3D[i] = data[1:4]
self.point3D_colors[i] = data[4:7]
self.point3D_errors[i] = data[7]
track_len = data[8]
track_len = self.read_next_bytes(fid, num_bytes=8, format_char_sequence="Q")[0]

self.point3D_id_to_point3D_idx[self.point3D_ids[i]] = i

data = struct.unpack(f'{2*track_len}I', f.read(2 * track_len * 4))
track_elems = self.read_next_bytes(fid, num_bytes=8*track_len,format_char_sequence="ii"*track_len)

self.point3D_id_to_images[self.point3D_ids[i]] = \
np.array(data, dtype=np.uint32).reshape(track_len, 2)
np.array(track_elems, dtype=np.uint32).reshape(track_len, 2)

def _load_points3D_txt(self, input_file):
self.points3D = []
Expand Down