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The extraction of oil and gas resources has led to the establishment of hundreds of thousands of wellsites across Alberta1, many of which are located within the boreal forest2. Reclamation efforts aim to restore disturbed lands to their original ecological state3. Conventional ground-based surveys remain the primary means of reclamation certification monitoring4; however, this is a time-consuming and labor-intensive process that is becoming less efficient as the number of disturbed and reclaimed areas continues to increase.
Recent advances in remote sensing (RS) technologies, especially the use of remotely piloted aircraft systems (RPAS), offer promising solutions to the spatial and temporal challenges of wellsite monitoring5,6,7,8. These platforms deliver very high-resolution data, allowing accurate measurements at the individual tree level. Integration with artificial intelligence (AI), as we have seen in recent years9,10,11, facilitates the processing and analysis of large remotely sensed data sets through the automation of vegetation detection and measurement. However, the generation of appropriate training and validation data sets for deep learning (DL) models remains the main challenge, particularly for 3D data sets.
This protocol outlines a step-by-step workflow for collecting, processing, aligning, and merging RPAS-based LiDAR and multispectral (MS) data from forested environments to delineate individual trees. This method uses the newly developed TreeAIBox12 plugin, integrated into CloudCompare, to analyze the RPAS-derived point cloud for individual tree crown segmentation. The plugin introduces a novel 3D DL approach based on the TreeisoNet13 model, a suite of supervised deep neural networks tailored for 3D tree segmentation, which was trained and verified on RPAS-derived datasets from five different reclaimed wellsites. The sites selected for the model training varied in tree heights, densities, and species composition to ensure the generalizability of the model. In addition, the training dataset included data collected during three consecutive seasons: summer (Aug 2023), fall (Oct 2023), and spring (May 2024) to ensure that the model could accurately perform under different seasonal conditions with variations in tree visibility. The plugin automates the processes of point cloud filtering (trees versus ground), detection of treetops, and segmentation of individual tree crowns. The output of the plugin could be used to calculate vegetation metrics, such as crown area, canopy fraction, stem density, and tree heights, used for post-reclamation vegetation monitoring.
The TreeisoNet model, integrated into the TreeAIBox plugin, offers significant improvements over traditional 3D segmentation methods such as watershed segmentation or ShortestPath. TreeisoNet has reported higher accuracy across diverse forest types, demonstrating the advantages of a supervised deep learning approach over unsupervised alternatives13. Specifically, the treetop locator module (TreeLoc) achieved an average F1 score of 0.96, significantly outperforming the local maximum (LM) method, which averaged an F1 score of 0.5713. Similarly, the crown delineation module (TreeOff) recorded an average mean Intersection over Union (mIoU) of 0.85, surpassing traditional Watershed3D (mIoU 0.68) and ShortestPath methods (mIoU 0.79)13. These metrics highlight TreeisoNet's superior accuracy in detecting treetops and delineating crowns, particularly in complex environments like reclaimed wellsites with varying tree heights, stem densities, and species compositions.
The TreeisoNet model was trained on RPAS-derived LiDAR data with point density above 1100 points per square meter. The method described in this paper is focused on monitoring forest recovery in oil and gas wellsites; however, it could be adapted for use in other forested areas. The workflow is well-suited for young plantations and mixedwood forests with sparse to moderate stem density (<3,000 stems per ha), where occlusion is minimal. In closed-canopy or multi-layered forests, detection of understory trees may be reduced due to limited LiDAR penetration. The model supports both coniferous and deciduous canopies, though accuracy may vary with species-specific features, such as thin leaders in young conifers. The TreeAIBox plugin includes a library of predefined, pre-trained models that are designed to be broadly applicable across various forest types and validated on diverse datasets from reclaimed wellsites. Users can leverage these built-in models and adjust plugin parameters, such as maximum gap or minimum radius, to optimize outputs for their specific datasets without needing to train new models. This flexibility allows users to adapt the workflow to different forest conditions, such as varying tree heights or densities, directly within CloudCompare's user-friendly graphical user interface (GUI). The current version of the TreeAIBox plugin does not support training new models within the software itself; however, it is possible for advanced users to add new pre-trained models to the model library.
Protocol sections 1 and 2 describe our data collection and processing steps while section 3 of the protocol describes the use of the TreeAIBox plugin to extract tree metrics. Our specific research uses a fusion of drone-based LiDAR data and MS imagery; however, different procedures, equipment, and software could be applied to generate a high-density point cloud file for use in protocol section 3. This workflow represents a significant advancement in vegetation monitoring by integrating a state-of-the-art AI-driven tree segmentation approach with RPAS-based RS, enabling faster, accurate, and scalable assessments of forest recovery.