Canadian Forest Service Publications

Radar Forest Height Estimation in Mountainous Terrain Using Tandem-X Coherence Data. 2018. Chen, H., Cloude, S.R., Goodenough, D.G., Hill, D.A., Nesdoly, A. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, Volume: 11, Issue: 10.

Year: 2018

Issued by: Pacific Forestry Centre

Catalog ID: 39368

Language: English

Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.1109/JSTARS.2018.2866059

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In this paper, we consider the problem of radar estimation of forest canopy height in regions with dense forests and severe topography. We combine a reference digital elevation model with multiple satellite baselines from ascending and descending orbits to develop a merging algorithm relating single pass interferometric coherence to forest canopy height. We first describe the algorithm and processing steps used for height estimation and then apply the technique to a mountainous study site in British Columbia, Canada, using data from the Tandem-X satellite pair. We devise a new masking scheme to isolate potential problem areas in sloped terrain and apply the new merging algorithm by using multiple Tandem-X tracks to overcome the gaps left due to the masking procedure. The radar height products are validated by using a network of ground forest measurement sites and supporting lidar. The regression statistics show an r 2 of 0.70 and rmse of 4.1 m between the radar and the field measured heights. By examining height errors, we implement a new test for the presence of canopy extinction, or subcanopy surface scattering, and demonstrate that in the dense and mountainous forests of British Columbia, there are significant canopy extinction effects in X-band imagery.

Plain Language Summary

Height is one of the most important parameters in forestry. It is an indicator of the timber production potential of a stand and is closely related (through allometric relations) to forest biomass. In this manuscript we report on using operational space-borne radar satellite technology from German’s TanDEM-X mission to map forest canopy height over a large mountainous forest region near Vernon in BC. Rugged forested terrain with severe topography poses special problems for radar forest height estimation. We demonstrate how to use multiple TanDEM-X radar products to obtain acceptable forest canopy height information in regions with severe topography and quantify and/or highlight any limitations that may accrue. Spatially-extensive and cost effective forest height information is needed by the government of BC to better assess current forest status and update forest inventory across a range of forest regions. Our work with TanDEM-X radar data contributes to the development of forest canopy height information over large mountainous forest regions in BC and is aligned with the CFS efforts for responsible resource development and information to manage Canada’s forest lands and natural resources