Revise IMU/TUM docs, enable exporting them by default

docs/GroundTruthAnnotations.md

@@ -145,7 +145,9 @@ To visualize point trajectories for a scene, run:
 python infinigen/tools/results/visualize_traj.py path/to/your/scene/frames
 ```
 
-### Camera Intrinsics & Extrinsics
+### Camera Pose
+
+##### Intrinsic & Extrinsic Matrices
 
 Camera intrinsics and extrinsics are stored as a numpy ".npz" file inside the "camview" folder.
 
@@ -155,21 +157,22 @@ The camera pose is stored as a 4 x 4 numpy matrix mapping from camera coordinate
 
 As is standard in computer vision, the assumed world coordinate system in the saved camera poses is +X -> Right, +Y -> Down, +Z Forward. This is opposed to how Blender internally represents geometry, with flipped Y and Z axes.
 
-### IMU and TUM
-
-IMU and TUM output is stored as ".txt" files inside the "imu_tum" folder. Enable IMU and TUM collection with config `infinigen_examples/configs_nature/extras/imu.gin`:
+##### Camera Velocity / Acceleration (IMU)
 
-```
---configs imu
-```
+Camera velocity / acceleration is stored as ".txt" files inside the "frames/imu_tum" folder.
 
 Inertial Measurement Unit (IMU) records the rotational velocity and linear acceleration of each camera at each frame. Each row contains the timestamp, rotational velocity (x y z), and linear acceleration (x y z) with each value separated by a space:
 
 ```
 timestamp rv_x rv_y rv_z a_x a_y a_z
 ```
 
-The [TUM trajectory format](https://github.com/MichaelGrupp/evo/wiki/Formats#tum---tum-rgb-d-dataset-trajectory-format) records the pose of the camera at each frame. Each row contains the timestamp, position, and rotation (as quarternion) with each value separated by a space:
+##### TUM Trajectory Format
+
+For convenience, we also save the trajectories of any animated cameras in the [TUM trajectory format](https://github.com/MichaelGrupp/evo/wiki/Formats#tum---tum-rgb-d-dataset-trajectory-format).
+
+
+Each row contains the timestamp, position, and rotation (as quarternion) with each value separated by a space:
 
 ```
 timestamp x y z q_x q_y q_z q_w

infinigen_examples/generate_indoors.py

@@ -244,13 +244,9 @@ def pose_cameras():
     def animate_cameras():
         cam_util.animate_cameras(camera_rigs, solved_bbox, scene_preprocessed, pois=[])
 
-        save_imu_tum_data = overrides.get("save_imu_tum_data")
-        if save_imu_tum_data:
-            frames_folder = output_folder.parent / "frames"
-            animated_cams = [
-                cam for cam in camera_rigs if cam.animation_data is not None
-            ]
-            save_imu_tum_files(frames_folder / "imu_tum", animated_cams)
+        frames_folder = output_folder.parent / "frames"
+        animated_cams = [cam for cam in camera_rigs if cam.animation_data is not None]
+        save_imu_tum_files(frames_folder / "imu_tum", animated_cams)
 
     p.run_stage(
         "animate_cameras", animate_cameras, use_chance=False, prereq="pose_cameras"

infinigen_examples/generate_nature.py

@@ -351,11 +351,9 @@ def flying_creatures():
     def animate_cameras():
         cam_util.animate_cameras(camera_rigs, bbox, scene_preprocessed, pois=pois)
 
-        save_imu_tum_data = params.get("save_imu_tum_data")
-        if save_imu_tum_data:
-            frames_folder = output_folder.parent / "frames"
-            animated_cams = [cam for cam in camera_rigs if cam.animation_data is not None]
-            save_imu_tum_files(frames_folder / "imu_tum", animated_cams)
+        frames_folder = output_folder.parent / "frames"
+        animated_cams = [cam for cam in camera_rigs if cam.animation_data is not None]
+        save_imu_tum_files(frames_folder / "imu_tum", animated_cams)
 
     p.run_stage(
         "animate_cameras",