tandem-x: mission and science exploration

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Folie [email protected] - 25.01.2007

TanDEM-X: Mission and Science Exploration

Irena Hajnsek & Alberto Moreira TDX Science Team

German Aerospace Center (DLR)Microwaves and Radar Institute

Folie 2Microwaves and Radar Institute

The main goal of the TanDEM-X mission is the generation of a world-wide, consistent, timely and high-precision digital elevation model (DEM) according to the HRTI-3 standard Demonstration of new SAR Techniques (ATI, MTI, Digital Beamforming, Pol-InSAR, etc.)

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1

2

3

4

5

0 50 Coverage in Mio km²

Airborne

LIDAR

Airborne SAR

Photogrammetry

SRTM-C (restric

ted)

HR Satellites

Aster

SRTM-C

(free)

SRTM-X

TanDEM-X

ERS Tandem

SPOT 5 HRS

Product comparison

HR

TI /

DTE

D L

evel

USGS GTOPO30

Primary Mission Goal

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HRTI-3 DEM Specification

0.4 arcsec (~ 12 m)fixed latitude/longitude rasterHorizontal Post Spacing

2 m90 % point-to-point errorsRelative Vertical Accuracy

10 m90 % single point errorAbsolute Vertical Accuracy

10 m90 % circular errorHorizontal Accuracy

ValueSpecificationRequirement

absolute height error single point errors

(90% confidence interval)

point-to-point errors(90% confidence interval)

hΔ

hΔ⋅2~

hΔ

relative height errorDefinition of 90% point-to-pointerrors: 1°

1°

hHRTIh σ⋅≈Δ 33.2%90


TanDEM-X Radar Techniques and Application Areas

Digital Elevation Model (DEM)

Radar Data Product (RDP)

TanDEM-X ApplicationAcross-track Along-track New Techniques

Land Cover &

Vegetation

Land Environment

Glaciology/H

ydrologyG

eology

Oceanography

TrafficO

ceanographyH

ydrology/Glaciology

Bistatic Processing

Pol-InSAR

Digital B

eamform

ingSuper R

esolutionForm

ation FlyingInSA

R Processing

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Radar Data Products• Standard DEMs

- Δh = 2m @ 12m posting (HRTI-3)

- also: 1m @ 25m and 0.5m @ 50m 4m @ 6m (on special request)

- global access

• Customised DEMs- improved resolution

(e.g. 1m @ 6m ~ HRTI-4)- multiple DEMs (different seasons/years)- only on local/regional basis

• Supporting information- geocoded SAR images- coherence maps- height error maps

• TanDEM-X provides data for- along-track interferometry - polarimetric SAR interferometry- four phase centre MTI- digital beamforming, …

• Policy- user is responsible for higher level

data production- supporting analysis by DLR

• Deliverables- SLC SAR images- auxiliary data (baselines, …)- interferograms (if applicable)- SAR raw data (on special request)

DEM Products

TanDEM-X Product Classes


Scientific User Requirements Survey

JUSTIFICATION & NEEDS

TECHNICAL REQUIREMENTS

PRODUCT DEFINITION

CONSOLIDATED

SCIENTIFIC

REQUIREMENTS

Science Response

1. Justification and Needs: General frame(application area, needs, National/European/International relevance, justification)

2. Technical Requirements: Quantitative display(performance, operation, product)

3. Product Acceptance: Defined Products(defined and being confirmed by the science team)

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Capabilities of TanDEM-X

TanDEM-X is a highly flexible sensor which enables multiple powerful imaging modes

4 Phase Center MTI (traffic, …)

PolInSAR (vegetation height, …)

Digital Beamforming (HRWS)Bistatic Imaging (classification, ..)

Large Scale Velocity Fields (ocean currents, glacier flow, …)

Moving Object DetectionTemporal Coherence Maps

Digital Elevation ModelsSpatial Coherence (forest, …)

Double DInSAR (change maps, ..)

High Resolution Radar Maps

New TechniquesAlong-Track InterferometryCross-Track Interferometry

r+Δr r

t+Δt t

interferometric modes(bistatic, alternating, monostatic)SAR modes(ScanSAR, Stripmap, …)

cross-track baselines(0 km to several km)along-track baselines

(0 km to several 100 km)

polarisations(single, dual, quad)…

bandwidth / resolution(0 ... 150/300 MHz) incident angles(20° ... 55°)


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Across-Track Interferometry

Topography Navigation Urban areas

Crisis management Glaciology Oceanography

Geology Hydrology Land cover

Scientific Applications


Along-Track Interferometry & New Techniques

RxθTxθ

φ

RxθTxθ

φ

ReceiverTransmitter ReceiverTransmitter

64 km/h

56 km/h

68 km/h

Ocean Currents Traffic Monitoring Glacier Mass Balance

Bi-Static SAR Polarimetric InSAR Digital Beamforming

InSAR Processing Super Resolution Formation Flying

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Single Pass X-Band InSAR Application Examples for TanDEM-X

Svalex campaign 2005 over the Austfonna glacierTopography measurements

Urban area campaign 2005 campaign over MunichCoherent scatterer detection (single and quad pol)

Boreal forest mapping campaign in FinlandBoreal forest heights estimation and comparison

2D ocean velocity measurementsFirst simulation results

Across-track

Along-track

New Techniques

New Techniques+


Cooperation between two Institutions:1. DLR-HR (Microwaves and Radar Institute)

* Pol-InSAR measurements over land ice* penetration depth at different frequencies* retrieval of glacier topography* estimation of internal ice structures

2.AWI-Potsdam (Alfred-Wegner Institute)* measurements of optical, chemical, and physical

properties of Arctic aerosols (Arctic Haze)3.AWI-Bremerhaven (Alfred-Wegner Institute)

* boundary layer meteorology * transfer of atmospheric momentum to sea ice* use of radar imagery to quantify ice ks

SVALEX 2005 – Svalbard Airborne Experiment

Sensors:1. E-SAR Radar System2. Meteopod (wind

velocity, humidity, temp.)

3. Laser Altimeter4. KT15 (surface temp.)5. Linescan camera

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Austfonna ETON (GlacierArea): Single InSAR X- band @VV

Amplitude VV

(mean dB -8.32)

InSAR Phase VV InSAR Coh. VV

(mean coh: 0.82)

az

rg


Summit Area: X- band (VV) Penetration depth

4.5Phase Difference [mean]

7.7Penetration Depth [m]

0.82InSAR Coherence

X BandVV

Frequency/Polarisation

Amplitude InSAR Coh

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Coherent Scatterers (CSs) Detected at X-band

Chirp bandwidth 100MhzRange resolution 1.5m Azimuth resolution 0.63m

Near range

CSs are detected through spectral correlation in range direction

Number of points detected ~ 95000

HH / X Band / Munich CS / HH / X Band / Munich


PI-SAR X-band Test Site: Gifu, Japan

Courtesy for the provision of X Band data: Hiroshi Kimura

Detection of Coherent Points

R: HHG: HVB: VV

Polarimetric SAR X Band for CS’s Detection

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Test Site: Oberpfaffenhofen

Amplitude Image – X-band Interferometric Phase – Baseline 1 Interferometric Phase – Baseline 2

Interferometric Coherence - Baseline 1 Interferometric Coherence - Baseline 2

X Band Single-Pass Dual Baseline Interferometry


E-SAR / Test Site: Oberpfaffenhofen

Amplitude Image – X-band Interferometric Coherence - Baseline 1 Interferometric Coherence - Baseline 2

X Band Single-Pass Dual Baseline Interferometry

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0

0

E-SAR / Test Site: Helsinki, Finland

Forest Height estimated at X-band & HUTSCAT Height Profiles

X Band Single-Pass Interferometry Boreal forest height inversion


2-D Current Measurements with TanDEM-XSquinted Split Antenna Mode

Ocean EddieSimulated Tandem-XMeasurement

Proposal by IMF to use Tandem-Xin a squinted split antenna mode

configuration for 2-D currentmeasurements

Courtesy: IMF Johannes Schulz-Stellenfleth

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Summary: Science Exploitation

TanDEM-X will provide novel DEM quality fully compliant to a variety of different scientific applications with global access.

TanDEM-X will demonstrate new SAR techniques in space for the development of future SAR systems.

TanDEM-X will deliver two main categories of products (DEM & RDP)

TanDEM-X mission is an evolution capitalizing on technology and experience from SRTM and TerraSAR-X.

Science

TanDEM-X is a unique system accounting for scientific(ongoing development), technical (experimental) and commercial (operational) demands.


Next X-band Satellite Mission

tandem-x: mission and science exploration

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