DATA_DICTIONARY.md

MVOT data dictionary

Video records

Each line in data/metadata.jsonl describes one video. Hugging Face VideoFolder exposes the same fields and loads file_name as the video feature.

Field	Type	Description
file_name	string	Path from data/metadata.jsonl to the MP4 file.
sample_id	string	Unique identifier for the sequence.
subset	string	regular or occlusion.
lighting	string	day, dusk, or night.
camera_tilt	string	0degree, 10degree, or 20degree. All dusk and night sequences use 0degree.
view	string	MatrixCity camera-trajectory region: bottom, left, right, or top.
segment_id	integer	Numeric segment identifier. It is not globally unique.
annotation_path	string	Repository-relative path to the canonical CSV annotation.
has_annotations	boolean	Whether the sequence includes canonical frame annotations. This is true for every published sequence.
frame_count	integer	Number of video frames.
annotation_frame_count	integer	Number of frame annotation records.
bbox_frame_count	integer	Number of frames with all four box coordinates.
usable_bbox_frame_count	integer	Number of frames with a box and no active invalid marker.
width, height	integer	Video dimensions in pixels.
fps	number	Video frame rate.
duration_seconds	number	Video duration in seconds.
codec	string	Video codec.
occlusion_values	list[string]	Distinct non-null frame-level occlusion labels in the sequence.
similar_values	list[string]	Distinct non-null similar-object labels in the sequence.
sha256	string	SHA-256 digest of the MP4 file.
annotations	list[object]	Ordered frame-level annotation records.

Frame annotations

Field	Type	Description
frame_id	integer	One-based frame index.
bbox_xywh	list[number] or null	Bounding box as [left, top, width, height] in pixels.
has_bbox	boolean	true when all four box coordinates are present.
source_marked_invalid	boolean	true when an annotation-level invalid marker or range covers the frame.
invalid_note	string or null	Original invalid marker on the row, such as 12-100 or invalid.
occlusion_raw	string or null	Original frame-level occlusion value: no, yes, 1, or 2.
similar_raw	string or null	Original similar-object value: no or yes.

Canonical CSV annotations

Each file under annotations/ contains one row per frame. The CSV columns are:

frame_id,bbox_left,bbox_top,bbox_width,bbox_height,has_bbox,
source_marked_invalid,invalid_note,occlusion_raw,similar_raw

The line break above is for readability only. Empty bounding-box cells indicate a missing box. Boolean values are written as lowercase true and false.

Coordinate convention

(0, 0) --------------------> x / bbox_left
  |
  |       +-------------+
  |       | bounding box|
  |       +-------------+
  v
y / bbox_top

Bounding boxes use [left, top, width, height] in pixel coordinates. Audited boxes lie within the 1024 x 1024 frame bounds.

Value interpretation

• Missing boxes remain explicit as null values.
• Invalid ranges are expanded into source_marked_invalid while the original text remains available in invalid_note.
• occlusion_raw preserves the supplied labels without assigning an undocumented meaning to numeric values.
• subset is the sequence-level grouping and is independent of occlusion_raw.
• All published videos contain 100 frames and 100 ordered annotation records.

Provenance

The associated paper describes MVOT as a synthetic dataset rendered from MatrixCity in Unreal Engine. It uses regularly sampled camera positions, fixed camera height, controlled scene pitch and illumination, and bounding boxes obtained through the Unreal Engine actor-tracking API.