| # Real4D data format |
|
|
| ## Paths |
|
|
| The first path component identifies the source subset (`dynerf` for N3DV or |
| `meetroom`), followed by a scene. Within each scene, modalities are grouped so |
| that large subsets can be downloaded independently. |
|
|
| For trajectory `cam00_01` and zero-based frame index `i`, use file number |
| `i + 1`: |
|
|
| ```text |
| images/cam00_01/cam00_01_000001.jpg |
| depths/cam00_01/cam00_01_000001.jpg.geometric.png |
| depth_vis/cam00_01/cam00_01_000001.jpg |
| camera_params/cam00_01.json # entry 0 |
| ``` |
|
|
| ## RGB |
|
|
| RGB frames are 8-bit three-channel JPEG files. N3DV-derived frames have size |
| 1352 x 1014; MeetRoom-derived frames have size 1280 x 720. |
|
|
| ## Depth |
|
|
| Depth files are single-channel 16-bit PNG images. A stored value `d` represents |
| `d / 1000` meters. Value zero is the invalid mask and indicates negligible |
| accumulated opacity. These values are rendered pseudo-labels derived from the |
| reconstructed dynamic scene, not measurements from a depth sensor. |
|
|
| ```python |
| from PIL import Image |
| import numpy as np |
| |
| depth_mm = np.asarray(Image.open(depth_path), dtype=np.uint16) |
| valid = depth_mm > 0 |
| depth_m = depth_mm.astype(np.float32) / 1000.0 |
| ``` |
|
|
| `depth_vis` is only a colorized preview and must not be used as numeric depth. |
|
|
| ## Camera manifest |
|
|
| Each `<trajectory>.json` is a list of 300 dictionaries in temporal order. The |
| main fields are: |
|
|
| | Field | Meaning | |
| |---|---| |
| | `timestamp` | Scene time in seconds. | |
| | `w2c` | 4 x 4 world-to-camera homogeneous transform. | |
| | `R` | 3 x 3 rotation component used by the renderer. | |
| | `T` | 3-vector translation component used by the renderer. | |
| | `fl_x`, `fl_y` | Focal lengths in pixels. | |
| | `cx`, `cy` | Principal point in pixels. | |
| | `FoVx`, `FoVy` | Horizontal and vertical field of view in radians. | |
| | `width`, `height` | Image dimensions in pixels. | |
| | `image_name` | Source reference-camera identifier; not an output filename. | |
|
|
| The camera matrix is analytically prescribed along the interpolation path. It |
| is exact with respect to that virtual trajectory; it is not an SfM/SLAM |
| estimate. Load the JSON record at list index `i` together with file number |
| `i + 1`. |
|
|
| ## Trajectories |
|
|
| `cam{a}_{b}` denotes the ordered interpolation from reference camera `a` to |
| reference camera `b`. Because the pair is ordered, `cam00_01` and `cam01_00` |
| are distinct. `cam00_00` is a static-viewpoint temporal sequence. Every |
| trajectory contains 300 frames spanning the scene's 10-second temporal extent. |
|
|
| ## Preview videos |
|
|
| `video/<trajectory>_rgb.mp4` and `video/<trajectory>_depth.mp4` are provided for |
| quick browsing at 30 fps. They are convenience derivatives; image sequences |
| and camera JSON are the authoritative data. |
|
|
|
|
