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README.md

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+# DONUT (Dataset Of MaNifold strUcTures)
+
+
+This repository contains a dataset of 3D samples made of watertight meshes and corresponding point clouds. Each sample is composed of one or several watertight mesh components and one 8192-point cloud representation.
+
+The dataset contains **29,517 samples** in total.
+
+## Overview
+
+The figure below shows a few samples from the dataset together with their labels.
+
+![A few DONUT samples and their labels](static/donut_samples.png)
+
+## Contents
+
+The repository is organized as follows:
+
+```text
+.
+├── metadata.csv
+├── obj/
+│   ├── shard_0/
+│   ├── shard_1/
+│   └── shard_2/
+└── pcd/
+    ├── shard_0/
+    ├── shard_1/
+    └── shard_2/
+```
+
+- `obj/` contains the mesh files as `.npz` archives.
+- `pcd/` contains the point clouds as `.npy` files.
+- `metadata.csv` contains one row per sample with topological metadata.
+
+There are **29,517** mesh files in `obj/` and **29,517** point cloud files in `pcd/`.
+
+## File Format
+
+### Meshes
+
+Each mesh sample is stored as an `.npz` file in `obj/`. The archive contains:
+
+- `vertices.npy`
+- `faces.npy`
+
+A sample may contain one or several watertight connected mesh components.
+
+### Point Clouds
+
+Each point cloud sample is stored as a `.npy` file in `pcd/`.
+
+Each point cloud contains **8192 points** and corresponds to the sample with the same `id`.
+
+## Sample Identification
+
+Each sample is identified by a unique `id` string.
+
+The same `id` is used in:
+
+- the filename in `obj/`
+- the filename in `pcd/`
+- the `id` column in `metadata.csv`
+
+For example, if a sample has id `abc123`, its files are:
+
+- `obj/.../abc123.npz`
+- `pcd/.../abc123.npy`
+
+## Metadata
+
+`metadata.csv` contains the following columns:
+
+- `id`: unique identifier of the sample
+- `genus`: total number of holes across all mesh components in the sample
+- `components`: total number of connected mesh components in the sample
+- `sample_code`: array of 6 integers describing how many components of each genus are present
+
+## Meaning of `sample_code`
+
+`sample_code` is an array of 6 integers:
+
+```text
+[n0, n1, n2, n3, n4, n5]
+```
+
+Here, `ni` is the number of mesh components in the sample whose genus is `i`.
+
+So:
+
+- `n0` is the number of genus-0 components
+- `n1` is the number of genus-1 components
+- `n2` is the number of genus-2 components
+- `n3` is the number of genus-3 components
+- `n4` is the number of genus-4 components
+- `n5` is the number of genus-5 components
+
+From `sample_code`, the metadata values are computed as:
+
+```text
+genus = sum(i * ni for i in [0, 1, 2, 3, 4, 5])
+components = sum(ni for i in [0, 1, 2, 3, 4, 5])
+```
+
+In other words:
+
+- `genus` is the total number of holes in the full sample
+- `components` is the total number of connected components in the full sample
+
+The distribution of labels in the dataset is shown below.
+
+![Distribution of DONUT labels](static/donut_distrib.png)
+
+## Examples
+
+```text
+sample_code = [2, 1, 0, 0, 0, 0]
+```
+
+This means:
+
+- 2 components of genus 0
+- 1 component of genus 1
+- total genus = 0 * 2 + 1 * 1 = 1
+- total components = 2 + 1 = 3
+
+## Summary
+
+DONUT is a dataset of **29,517** samples of manifold 3D structures.
+
+Each sample provides:
+
+- one mesh file in `.npz` format
+- one 8192-point cloud in `.npy` format
+- one metadata entry in `metadata.csv`
+
+The metadata describes the global topology of each sample through its total genus, number of connected components, and component-wise genus distribution.