fix bugs in COLMAP images text loading (#177)

The current implementation of the _load_images_txt function in the main
branch cannot handle cases where images have empty feature points. This
results in subsequent image information failing to load properly. This
PR resolves this issue.

Signed-off-by: NotMorven <[email protected]>

Author: NotMorven

fvdb_reality_capture/sfm_scene/_colmap_utils/scene_manager.py

@@ -184,42 +184,25 @@ def _load_images_bin(self, input_file):
     def _load_images_txt(self, input_file):
         self.images = OrderedDict()
 
-        with open(input_file, "r") as f:
-            is_camera_description_line = False
-
-            for line in iter(lambda: f.readline().strip(), ""):
-                if not line or line.startswith("#"):
-                    continue
-
-                is_camera_description_line = not is_camera_description_line
-
-                data = line.split()
-
-                if is_camera_description_line:
-                    read_quat = np.array(list(map(float, data[1:5])))
-                    read_pos = np.array(list(map(float, data[5:8])))
-                    image_id = int(data[0])
-                    image = Image(
-                        data[-1],
-                        int(data[-2]),
-                        Quaternion(read_quat),
-                        read_pos,
-                    )
-                else:
-                    points_2d_x = [float(x) for x in data[::3]]
-                    points_2d_y = [float(y) for y in data[1::3]]
-                    point3d_ids = [np.uint64(pid) for pid in data[2::3]]
-                    image.points2D = np.array([points_2d_x, points_2d_y]).T
-                    image.point3D_ids = np.array(point3d_ids, dtype=np.uint64)
-
-                    # automatically remove points without an associated 3D point
-                    # mask = (image.point3D_ids != SceneManager.INVALID_POINT3D)
-                    # image.points2D = image.points2D[mask]
-                    # image.point3D_ids = image.point3D_ids[mask]
-
-                    self.images[image_id] = image
-                    self.name_to_image_id[image.name] = image_id
-
+        with open(input_file, "r") as fid:
+            while True:
+                line = fid.readline()
+                if not line:
+                    break
+                line = line.strip()
+                if len(line) > 0 and line[0] != "#":
+                    elems = line.split()
+                    image_id = int(elems[0])
+                    qvec = np.array(list(map(float, elems[1:5])))
+                    tvec = np.array(list(map(float, elems[5:8])))
+                    camera_id = int(elems[8])
+                    image_name = elems[9]
+                    elems = fid.readline().split()
+                    xys = np.column_stack([tuple(map(float, elems[0::3])), tuple(map(float, elems[1::3]))])
+                    point3D_ids = np.array(tuple(map(int, elems[2::3])))
+                    self.images[image_id] = Image(image_name, camera_id, Quaternion(qvec), tvec)
+                    self.images[image_id].points2D = xys
+                    self.images[image_id].point3D_ids = point3D_ids
                     self.last_image_id = max(self.last_image_id, image_id)
 
     # ---------------------------------------------------------------------------
@@ -386,7 +369,11 @@ def _save_images_txt(self, output_file):
                 print >> fid, image.camera_id, image.name
 
                 data = np.rec.fromarrays(
-                    (image.points2D[:, 0], image.points2D[:, 1], image.point3D_ids.astype(np.int64))
+                    (
+                        image.points2D[:, 0],
+                        image.points2D[:, 1],
+                        image.point3D_ids.astype(np.int64),
+                    )
                 )
                 if len(data) > 0:
                     np.savetxt(fid, data, "%.2f %.2f %d", newline=" ")
@@ -591,7 +578,14 @@ def delete_images(self, image_list):
 
     # camera_list: set of cameras whose points we'd like to keep
     # min/max triangulation angle: in degrees
-    def filter_points3D(self, min_track_len=0, max_error=np.inf, min_tri_angle=0, max_tri_angle=180, image_set=set()):
+    def filter_points3D(
+        self,
+        min_track_len=0,
+        max_error=np.inf,
+        min_tri_angle=0,
+        max_tri_angle=180,
+        image_set=set(),
+    ):
 
         image_set = set(image_set)