Treffer: Handheld photogrammetry advances capabilities to systematically characterize broken‐rock habitat.

Structurally complex habitats play a critical role in the survival of wildlife species by providing food, thermal refuges, and protection from predation. However, the same complex properties that make these habitats suitable for wildlife also make them challenging to characterize and assess their ecological value. Traditional methods for characterizing complex habitats are labor intensive and lack the fine‐scale resolution needed for accurate habitat assessment. We developed a workflow using handheld photogrammetry to systematically map and measure fine‐scale habitat characteristics in broken‐rock patches, and identify key habitat features relevant to rock‐dwelling wildlife. To test our workflow, we established 10 m × 10 m plots at 15 talus patches within the North Cascades National Park Service Complex in Washington, USA, and used a structured approach to capture overlapping images with an iPad Pro. We processed images in Agisoft Metashape, using structure‐from‐motion (SfM), to create georeferenced digital elevation models (DEMs) and orthomosaics. We used the Python package segmenteverygrain to semi‐automatically segment the orthomosaic rasters into individual rocks and enable us to quantify size and shape. For classifying areal cover, we created training samples and used a support vector machine algorithm to classify rasters into 3 categories (rock, moss, and vegetation). Using the DEMs, we characterized surface roughness at a 15‐cm resolution. Photogrammetry successfully generated high‐resolution orthomosaics and DEMs for all surveyed plots (GSD ≤1.05 mm). Image segmentation and supervised classification provided detailed quantitative data, revealing variations in rock size, shape, cover types, and surface roughness characteristics. Mean rock volume varied ~60‐fold, and vegetation cover ranged from 0% to 19% across plots. Our workflow provides a scalable and adaptable tool for fine‐scale habitat characterization of structurally complex systems, providing information for species and habitat monitoring. [ABSTRACT FROM AUTHOR]

Copyright of Wildlife Society Bulletin (2328-5540) is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)