Measurement of fine-spatial-resolution 3D vegetation structure with airborne waveform lidar: Calibration and validation with voxelised terrestrial lidar
Hancock, S; Anderson, K; Disney, M; et al.Gaston, KJ
Date: 11 November 2016
Journal
Remote Sensing of Environment
Publisher
Elsevier
Publisher DOI
Related links
Abstract
Vegetation structure controls habitat availability, ecosystem services, weather,
climate and microclimate, but current landscape scale vegetation maps have lacked
details of understorey vegetation and within-canopy structure at resolutions finer
than a few tens of metres. In this paper, a novel signal processing method is used
...
Vegetation structure controls habitat availability, ecosystem services, weather,
climate and microclimate, but current landscape scale vegetation maps have lacked
details of understorey vegetation and within-canopy structure at resolutions finer
than a few tens of metres. In this paper, a novel signal processing method is used
to correctly measure 3D voxelised vegetation cover from full-waveform ALS data
at 1.5m horizontal and 50 cm vertical resolution, including understorey vegetation
and within-canopy structure. A new method for calibrating and validating the instrument specific ALS processing using high resolution TLS data is also presented
and used to calibrate and validate the ALS derived data products over a wide range
of land cover types within a heterogeneous urban area, including woodland, gardens and streets. This showed the method to accurately retrieve voxelised canopy
cover maps with less than 0.4% of voxels containing false negatives, 10% of voxels containing false positives and a canopy cover accuracy within voxels of 24%.
The method was applied across 100 km2
and the resulting structure maps were
compared to the more widely used discrete return ALS and Gaussian decomposed
waveform ALS data products. These products were found to give little information
on the within-canopy structure and so are only capable of deriving coarse resolution,
plot-scale structure metrics. The detailed 3D canopy maps derived from the new
method allow landscape scale ecosystem processes to be examined in more detail
than has previously been possible, and the new method reveals details about the
canopy understorey, creating opportunities for ecological investigations. The ca ibration method can be applied to any waveform ALS instrument and processing
method. All code used in this paper is freely available online through bitbucket
(https://bitbucket.org/StevenHancock/voxel lidar)
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