README.md

---
license: etalab-2.0
pretty_name: PureForestt
size_categories:
- 100K<n<1M
task_categories:
- image-classification
- other # point clouds classification
tags:
- IGN
- Aerial
- Environement
- Multimodal
- Earth Observation
- Lidar
- ALS
- Point Cloud
- Forest
- Tree Species
---

# Dataset Card for PureForest


## Context and Data
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The hereby PureForest dataset is derived from 449 different forests located in 40 French departments, mainly in the southern regions. 
It is characterized by two modalities: high density aerial Lidar point clouds with a density of 10 pulses per square meter, 
and high resolution aerial imagery with a spatial resolution of 0.2 m.

This dataset includes 135,569 patches, each measuring 50 m x 50 m, covering a cumulative exploitable area of 339 km². 
Each patch represents a monospecific forest, annotated with a single tree species labeled to facilitate classification tasks. 
The proposed classification has 13 semantic classes, hierarchically grouping 18 tree species from 9 different tree genera. 

A reference train/val/test split is provided.

Lidar points clouds            |  Aerial imagery
:-------------------------:|:-------------------------:
![](./imagery_18_classes.png)  |  ![](./lidar_18_classes.png)


## Dataset Structure
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The PureForest dataset consists of a total of 135,569 patches: 69111 in the train set, 13523 in the val set, and 52935 in the test set.
Each patch includes a high-resolution aerial image (250 pixels x 250 pixels) at 0.2 m resolution, and a point cloud of high density aerial Lidar (10 pulses/m², ~40pts/m²).
Band order is near-infrared, red, greeb, blue. For convenience, the Lidar point clouds are vertically colorized with the aerial images.

Lidar and imagery data were acquired over several years in distinct programs, and consequently they are asynchrone: depending on the location, up to 3 years might separate them. 


## Annotations
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Annotations were made at the forest level, and considering only monospecific forests. A semi-automatic approach was adopted in which pure forest polygons
were selected and then curated by expert photointerpreters from the IGN. The annotation polygons came from the [BD Forêt](https://inventaire-forestier.ign.fr/spip.php?article646), 
a forest vector database of tree species occupation in France. Ground truths from the [French National Forest Inventory](https://inventaire-forestier.ign.fr/?lang=en) 
were also used to improve the condidence in the purity of the forests.

| Class | Train (%) | Val (%) | Test (%) |
|-------|------------:|----------:|-----------:|
**(0) Deciduous oak**|22.92%|32.35%|52.59%
**(1) Evergreen oak**|16.80%|2.75%|19.61%
**(2) Beech**|10.14%|12.03%|7.62%
**(3) Chestnut**|4.83%|1.09%|0.38%
**(4) Black locust**|2.41%|2.40%|0.60%
**(5) Maritime pine**|6.61%|7.10%|3.85%
**(6) Scotch pine**|16.39%|17.95%|8.51%
**(7) Black pine**|6.30%|6.98%|3.64%
**(8) Aleppo pine**|5.83%|1.72%|0.83%
**(9) Fir**|0.14%|5.32%|0.05%
**(10) Spruce**|3.73%|4.64%|1.64%
**(11) Larch**|3.67%|3.73%|0.48%
**(12) Douglas**|0.23%|1.95%|0.20%

## Data Splits
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The polygons were sampled in southern France due to the partial availability of the Lidar data at the time of dataset creation. 
They are located in 40 distinct French administrative departments, covering a large diversity of territories and forests.
To define a common benchmark, we divided the data into train, val, and test sets, with a stratification on semantic labels. 
Annotation polygons are scattered across southern France, leading to a good geographical diversity within each semantic class. 
To account for the high spatial autocorrelation, the 70%-15%-15% split is performed at the annotation polygon level: 
each forest exclusively belongs to either the train, val, or test set.  
This makes PureForest suitable to evaluate the territorial generalization of classification models. 

Approximate positions of forests in PureForest:

![](./dataset_extent_map.excalidraw.png)

## Citation
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Please include a citation to the following article if you use the PureForest dataset:

```
@article{gaydon2024pureforest,
      title={PureForest: A Novel Dataset and Benchmarks for Tree Species Classification in Monospecific Forests from Aerial Lidar and Aerial Images}, 
      author={Charles Gaydon and Floryne Roche},
      year={2024},
      doi={TBD},
}
```


## Dataset license
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The "OPEN LICENCE 2.0/LICENCE OUVERTE" is a license created by the French government specifically for the purpose of facilitating the dissemination of open data by public administration.<br/>
This licence is governed by French law.<br/>
This licence has been designed to be compatible with any free licence that at least requires an acknowledgement of authorship, and specifically with the previous version of this licence as well as with the following licences: United Kingdom’s “Open Government Licence” (OGL), Creative Commons’ “Creative Commons Attribution” (CC-BY) and Open Knowledge Foundation’s “Open Data Commons Attribution” (ODC-BY).