Forest Height Estimation with X- Band InSAR: Phase Centre Location versus RVoG Florian Kugler, Irena Hajnsek, Seung-Kuk Lee & Konstantinos Papathanassiou German Aerospace Center (DLR) Microwaves and Radar Institute (HR)
Lineout Test Sites: FinSAR Campaign INDREX II: Mawas Kobernausser Wald TempoSAR Campaign: Traunstein Biosar II Campaign: Krycklan Issues: Phase Centre Height Forest Height Extinction Comparision/Combination of different baselines Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 2
Height Validation X band vs L band boreal forest Southern Finnland 0 X band validated against Scatterometer 0 0 0 Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 3
INDREX-II: Mawas Test Site • Peat swamp forest • Forest Height: 15m – 25m • Biomass around 100- 350t/ha • Uniform structure • Open canopy • Flat Topography Microwaves and Radar Institute / Pol Microwaves and Radar Institute / Pol - - InSAR Research Group InSAR Research Group 4
Mawas X band Validation with Lidar Lidar Strip Reference Height: Inversion I Top Canopy height 100 using φ 0 from (100 tallest tree per hectar) unvegetated area Lidar Strip was divided into 100 equal samples Phase Center Height Inversion II using σ 0.3 d B/m (mean Extinction Inversion I) Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 5
Test Site Kobernausser Wald Kobernausser Wald: • Upper Austria • Temperate managed forest • Hilly Topography • Inhomogenous Composition • Stands of different Heights from 4 to 35m and different age and different biomass • Domintated by Coniferous trees • Canopy mainly closed Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 6
Kobernausser Lidar Strip InSAR Coherence Amplitude Image Wald Dataset X Band Polarisation VV Single Pass Baseline :0.8m Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 7
Kobernausser Wald X band Validation with Lidar Inversion Inversion Lidar Phase Heights Heights h100 Center Inversion I using φ 0 from Lidar Reference Height: Top Canopy height h100 (100 tallest tree per hectar) Phase Center Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 8
Kobernausser Wald X band Extinction Estimation Stand: Mean Extinction from Inversion: 0.79dB/m Mean Extinction from Lidar h100: 0.82dB/m Extinction Extinction Mean Ground to Volume Ratio: 0.05 from height from Lidar estimation Inversion Mean forest Height, 25.7m 2dB/m 1dB/m 0dB/m Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 9
Traunstein Test Site Forest type Temperate Topography Moderate slopes Height 25 ~ 35m Species N. Spruce, E. Beech, White Fir Biomass 40 ~ 450 t/ha Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 10
Temposar data Full Baseline Half Baseline Coherence 0 to 1 Phase - π to π Coherence 0 to 1 Phase - π to π Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 11
Estimated Forest Heights Full Baseline Inversion using external ground phase Tends to underestimate high forests Scattering Centre clearly below estimated forest height 40m Inversion height Scattering Centre 20m 0m Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 12
Estimated Forest Heights Half Baseline Inversion using external ground phase Tends to underestimate high forests Scattering Centre clearly below estimated forest height Good Inversion Performance in near range 40m Inversion height Scattering Centre 20m 0m Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 13
Estimated Extinction Full Baseline Half Baseline Estimated from Height Estimated from Height Inversion Inversion Estimated with Estimated with Reference Height Reference Height Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 14
Lidar Tree Vegetation height 40m 20m Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 15 0m
Biosar II Test Site Krycklan Sweden Krycklan forest: Location: • middle Sweden • boreal forest • high topography Composition • stands of different Height • maximum forest height: ~ 30m • mean forest height: 17m • stands of different age and different biomass • domintated by Coniferous trees Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 16
Biosar data Full Baseline Half Baseline Coherence 0 to 1 Phase - π to π Coherence 0 to 1 Phase - π to π Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 17
Biosar dual Baseline Inversion results Forest Height Extinction 2dB/m 40m 1dB/m 20m 0dB/m 0m Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 18
Summary Forest Height Inversion using X-Band Forest height estimation using X band provides prommissing results for tropical as well as for temperate & boreal forest conditiions X band Phase Center is significantly lower than Pol-InSAR forest height Especially in less dense forest conditions as can be found in boreal forests X band could provide good results Limitting factor for X band is forest density If there is an external DEM available we can go even further The results show a high potential of TanDEMX for forest height estimation in certain ecosystems, even if Quad or Dual Pol data are available Microwaves and Radar Institute / Microwaves and Radar Institute / Pol Pol - - InSAR Research Group InSAR Research Group 19
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