Managing forest landing residue piles - a case study on the use of photogrammetry to support decision-making

Authors: Campbell Harvey, Ryan Drummond
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 2022, Issue N.Z.J.For. 67(1) 2022, pp 27–30, May 2022
Publisher: New Zealand Institute of Forestry

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Abstract: The piles of woody residues that accumulate at forest landings across New Zealand present various operational, safety and environmental challenges for foresters and logging crews. Being able to measure the dimensions of these piles would help make decisions about the potential recovery for a biomass market, but also for risk. For example, it is recommended that residue piles should be no deeper than 3 m due to self-ignition risk. Depth can be difficult to measure, especially on undulating terrain. This case study used Unmanned Aerial Vehicle (UAV)-based aerial photography to first improve the calculation of total pile volume, and second to provide a 3D map to help determine pile depth for targeted rehabilitation. A UAV was used to capture aerial photographs post-construction of a landing (before harvest), then again post-harvest with the residue pile formed. Georeferenced photogrammetric surface models were constructed and used to establish the relative height change of the surface pre- to post-harvest (and therefore total bulk volume) over the plan area of the pile. A ‘heat map’ of pile depth was generated, enabling assessment of areas requiring rehabilitation to meet best practice guidelines. This case study presents an improved methodology for assessing large piles over time, along with learnings of the method’s limitations for the practising forester.

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