A Comparison of P- and L-Band PolInSAR 3-D Forest...

A Comparison of P- and L-Band PolInSAR

3-D Forest Structure Estimates:

A Study Case in the Traunstein Forest

M. Pardini1, M. Tello Alonso

1, A. Toraño Caicoya

1,

M. Heym2, K. Papathanassiou

1

1 Microwaves and Radar Institute (DLR-HR)

German Aerospace Center (DLR)

2 Technische Universität München (TUM)

The Traunstein forest (TempoSAR„09 campaign, DLR E-SAR)

L-band P-band

April 27, 28

May 5, 11, 12

October 28

November 5

# of acquisition: 4 to 7 each flight

Max kz : 0.3 to 0.4 @ mid range

Bürgerwald Traunstein

Temperate mixed managed forest

Height Range (H100): 10 - 40m

Biomass Range: 40 ~ 450 t/ha

Moderate Slopes

Forest vertical reflectivity: L- vs P-band

Traunstein site (Germany), 4 tracks L / 5 tracks P, E-SAR, Capon

Lidar H100

Lidar DTM

590m

650m

590m

650m

590m

650m

590m

650m

590m

650m

590m

650m

Slant range (~1Km) Slant range (~1Km)

HH

VV

HV

HH

VV

HV

0 1 Intensity

L-band P-band

L-band HH+VV L-band HH-VV L-band HV

P-band HH+VV P-band HH-VV P-band HV

Dira

c-δ

gro

un

d a

fte

r

top

og

raph

y c

om

pe

nsa

tio

n

Ground Volume

( ) ( ) ( ) ( ) ( )V V G Gf z m z m z zω ω

Ground / Volume separation

( )V zReflectivity profile (2-layer+RVoG)

z

V V G GR C R C RMultibaseline-polarimetric cov. matrix

Algebraic solution based on SVD

Any ambiguity can be removed by assuming a

rank-deficient ground (Dirac-δ hyp.) +

knowledge of the ground height

Maximum ground / volume coherences

Ground / volume search segments

Ground / volume –only coherences after

ambiguity solution

Baseline 1

Baseline 2

Baseline K

[Tebaldini, 2010 – Ferro-Famil, et al. 2013]

HH HH

Ground / Volume separation

590m

650m

590m

650m

Ground Volume Ground Volume

L-band P-band

Ground-to-Volume power ratios

-10dB 10dB G2V power ratio

Growth

stages

LIDAR

H100

0m 45

L, HH P, HH

L, HV P, HV

-10 -5 0 5 10

L-band (dB)

Ground-to-volume ratio, HH

P-b

an

d (

dB

)

10

5

0

-5

-10

-10 -5 0 5 10

L-band (dB)

P-b

an

d (

dB

)

10

5

0

-5

-10

Ground-to-volume ratio, HV

Min / max Ground-to-Volume power ratios

Growth

stages

LIDAR

H100

0m 45

L, min P, min

L, max P, max

4.5dB

-15 -10 -5 0 5 10 15

Ground-to-volume ratio, dB

L-band

P-band

7.5dB

-10dB 10dB G2V power ratio

LiDAR

H100

Ground topography & Forest height

-5m 5

Gro

un

d t

op

og

rap

hy

Fo

res

t h

eig

ht

Est. error

Phase center of the

ground-only Fourier

profile

L-band

P-band

L-band

P-band

RMSE = 2m

ρ = 0.9

RMSE = 2.5m

ρ = 0.9

0 10 20 30 40 50

LiDAR H100, m

0 10 20 30 40 50

LiDAR H100, m

50

40

30

20

10

0

SA

R H

eig

ht,

m

50

40

30

20

10

0

SA

R H

eig

ht,

m

0m 50

Model-based inversion

from volume-only

coherences (exp. profile)

Vertical structure discrimination

1

1

log , K

i

Ki K i ii

jj

H p p p

MB Entropy

Calculated from the eigenvalues λ

of the MB covariance matrix

K: # of images

0 1 MB Entropy

L-band

P-band

Volume

only

Volume

only

Growth

stages

Young

Growing

Mature

Regen.

„Plenter“

0 0.2 0.4 0.6 0.8 1

MB Entropy, H

3

2

1

0

[-]

Normalized histogram

0 0.2 0.4 0.6 0.8 1

MB Entropy, H

3

2

1

0

[-]

Normalized histogram

20m x 20m multilook (slant) for both P- / L- band

Temporal variations at L-band (Capon)

Slant range (~0.6Km) Slant range (~0.6Km) Slant range (~0.6Km)

590m

650m HH

590m

650m VV

590m

650m HV

590m

650m HH

590m

650m VV

590m

650m HV

Slant range (~0.6Km) Slant range (~0.6Km) Slant range (~0.6Km)

590m

650m HH

590m

650m VV

590m

650m HV

590m

650m HH

590m

650m VV

590m

650m HV

Summary

P-band provides:

Increased sensitivity to larger forest structures relevant to forest biomass

Reduced attenuation through the vegetation: higher “visibility” of lower vegetation

layers as well as of the underlying ground

L-band provides:

scattering on smaller forest structures (branches, ..), thus sensitivity to forest

structures of ecological relevance

increased attenuation through the vegetation that provides a reduced “visibility” of the

underlying ground

L-band shows a reduced temporal stability

Increased sensitivity to vegetation / ground moisture conditions and seasonality

Potentially higher amount of information

… but at the same time it may increase interpretation ambiguities: to be discussed

with respect to specific applications and “robust” information extraction

A Comparison of P- and L-Band PolInSAR

3-D Forest Structure Estimates:

A Study Case in the Traunstein Forest

M. Pardini1, M. Tello Alonso

1, A. Toraño Caicoya

1,

M. Heym2, K. Papathanassiou

1

1 Microwaves and Radar Institute (DLR-HR)

German Aerospace Center (DLR)

2 Technische Universität München (TUM)

A Comparison of P- and L-Band PolInSAR 3-D Forest...

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