---
language:
- en
license: cc-by-4.0
task_categories:
- image-segmentation
pretty_name: COCOTree Annotation
---

# COCOTree

[**Paper**](https://huggingface.co/papers/2605.22068) | [**Code**](https://github.com/melonkick3090/COCOTree)

[![COCOTree annotation overview](figures/introduction_annotation.png)](figures/introduction_annotation.pdf)

COCOTree is an annotation-only release for open tree decomposition over
COCO images. Each image has two linked views: a semantic-node tree for local
labels and merged masks, and an instance-node tree for image-local mask
instances and visual parent-child links.

The full original COCO images are not redistributed here. This repository
includes the released annotations, metadata, validation files, and a small
sample folder for inspection.

Click either figure to open the original PDF.

## Annotation Views

Every non-root semantic node has a merged mask, bbox, label, semantic parent,
semantic children, and links to its instance nodes. Every instance node has
its own mask, bbox, label, semantic-node id, semantic parent/children,
instance parent, and instance children.

- Semantic nodes use source tree ids such as `n00014`.
- Instance nodes use image-local ids such as `n00014#1`.
- The synthetic roots are `n00000` and `n00000#1`.
- Masks are encoded as COCO compressed RLE.

## Construction Pipeline

[![COCOTree construction pipeline](figures/COCOTree_recursive_pipeline.png)](figures/COCOTree_recursive_pipeline.pdf)

The pipeline recursively proposes visible child labels, grounds them into
masks, filters invalid candidates, groups repeated masks into semantic nodes,
and materializes instance nodes with parent-child links.

## Dataset Scale

| Item | Count |
| --- | ---: |
| Images | 21,133 |
| Semantic nodes | 554,550 |
| Instance nodes | 1,816,065 |
| Unique labels | 3,508 |
| Max semantic depth | 8 |
| Max instance depth | 8 |

## Files

- `annotations/semantic_nodes.jsonl` and `annotations/semantic_edges.jsonl`:
  semantic tree nodes and edges.
- `annotations/instance_nodes.jsonl` and `annotations/instance_edges.jsonl`:
  instance tree nodes and edges.
- `annotations/image_dual_tree_summary.jsonl`: image-level counts and depth
  summaries.
- `annotations/parent_assignment_warnings.jsonl`: parent-assignment warnings
  from instance tree construction.
- `metadata/`: dataset stats, splits, label vocab, and evaluation protocol.
- `samples/`: small preview subset with images, annotations, overlay examples,
  and `dual_tree_viewer.html`.
- `figures/`: README preview images and the original PDF figures.

## Quick Validation

```bash
python scripts/verify_cocotree.py --release-root .
```

Generated: `2026-05-07T03:36:54Z`