fix the depth description

README.md

@@ -65,33 +65,34 @@ python SpaceSense-Toolkit/convert/airsim_to_yolo.py --raw-data data_example --ou
 
 | Modality | Format | Unit / Range | Description |
 |----------|--------|-------------|-------------|
-| RGB | PNG (1024x1024) | 8-bit color | Scene rendering |
-| Depth | PNG (1024x1024) | int32, millimeters (0 ~ 10,000,000 mm, background = 10,000 m) | Per-pixel depth map |
-| Semantic Segmentation | PNG (1024x1024) | uint8, class ID per pixel (0 = background) | Component-level segmentation mask |
-| LiDAR Point Cloud | ASC (x y z per line) | meters, 3 decimal places | Sparse 3D point cloud |
-| 6-DoF Pose | CSV | meters + Hamilton quaternion (w,x,y,z) | Camera-to-target relative pose |
+| RGB | PNG (1024x1024) | 8-bit color | Scene rendering from `cam0` |
+| Depth | NPZ (compressed) | int32, millimeters (`depth` key); background = 10,000 m | Per-pixel metric depth exported from AirSim `DepthPerspective` |
+| Semantic Segmentation | PNG (1024x1024, RGB color mask) | color-coded part labels | Component-level segmentation mask; toolkit maps colors to 7 semantic classes |
+| LiDAR Point Cloud | ASC (x,y,z per line) | meters, 3 decimal places | Sparse 3D point cloud |
+| 6-DoF Pose | CSV | meters + Hamilton quaternion (w,x,y,z) | Target-spacecraft pose in camera frame, plus service/camera pose in world frame |
 
 ## Coordinate System & Units
 
 | Item | Convention |
 |------|-----------|
-| Camera Frame | X-forward, Y-right, Z-down (right-hand system) |
+| Camera Frame | X-forward, Y-right, Z-down (FRD, right-handed) |
 | World Frame | AirSim NED, target spacecraft fixed at origin |
 | Quaternion | Hamilton convention: w + xi + yj + zk |
 | Euler Angles | ZYX intrinsic (Yaw-Pitch-Roll) |
 | Position | meters (m), 6 decimal places |
-| Depth Map | millimeters (mm), int32; deep space background = 10,000 m |
-| LiDAR | meters (m), .asc format (x y z), 3 decimal places |
-| Timestamp | YYYYMMDDHHMMSSmmm |
+| Depth Map | millimeters (mm), stored as compressed `.npz`; deep-space background = 10,000 m |
+| LiDAR | meters (m), `.asc` format (`x,y,z`), 3 decimal places |
+| Timestamp | `YYYYMMDDHHMMSSmmm` |
 
 ## Sensor Configuration
 
-### Camera (cam0)
+### Camera (`cam0`)
 
 - Resolution: 1024 x 1024
 - FOV: 50 degrees
-- Image types captured: RGB (type 0), Segmentation (type 5), Depth (type 2)
+- Image types captured: RGB (`Scene`, type 0), Segmentation (type 5), Depth (`DepthPerspective`, type 2)
 - TargetGamma: 1.0
+- Mounting offset: 1 m in front of the service spacecraft body origin
 
 ### LiDAR
 
@@ -99,7 +100,7 @@ python SpaceSense-Toolkit/convert/airsim_to_yolo.py --raw-data data_example --ou
 - Channels: 256
 - Vertical FOV: -20 to +20 degrees
 - Horizontal FOV: -20 to +20 degrees
-- Data frame: SensorLocalFrame
+- Data frame: `SensorLocalFrame`
 
 ## Data Split (Zero-shot / OOD)
 
@@ -113,21 +114,34 @@ The training and validation sets contain **completely non-overlapping satellite
 
 ## Data Organization
 
-Each `.tar.gz` file in the `raw/` folder contains data for one satellite:
+Each `.tar.gz` file in the `raw/` folder contains data for one satellite. The toolkit expects trajectory folders containing `image/`, `seg/`, `depth/`, `lidar/`, and `pose_ground_truth.csv`.
 
-```
-<timestamp>_<satellite_name>/
+Typical layout:
+
+```text
+<satellite_name>/ or <timestamp>_<satellite_name>/
 ├── approach_front/
-│   ├── rgb/              # RGB images (.png)
-│   ├── depth/            # Depth maps (.png, int32, mm)
-│   ├── segmentation/     # Semantic masks (.png, uint8)
-│   ├── lidar/            # Point clouds (.asc)
-│   └── poses.csv         # 6-DoF poses
+│   ├── image/              # RGB images (.png)
+│   ├── depth/              # Depth maps (.npz, int32, mm, key = depth)
+│   ├── seg/                # Semantic masks (.png, RGB color encoding)
+│   ├── lidar/              # Point clouds (.asc)
+│   └── pose_ground_truth.csv
 ├── approach_back/
 ├── orbit_xy/
 └── ...
 ```
 
+Some HuggingFace exports may contain one additional nesting level:
+
+```text
+<satellite_name>/
+└── <satellite_name>/
+    ├── approach_front/
+    ├── approach_back/
+    ├── orbit_xy/
+    └── ...
+```
+
 ## Semantic Class Definitions
 
 | Class ID | Name | Description |
@@ -154,4 +168,4 @@ This dataset is released under the [CC-BY-NC-4.0](https://creativecommons.org/li
 	year={2026},
 	url={https://arxiv.org/abs/2603.09320}
 }
-```
+```