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POLinsar Round Table - Seed Questions


SAR Polarimetric Interferometry session

Forestry session

Applications session

Land-agriculture applications session

Theoretical Modelling session

Airborne campaigns session

Spaceborne mission session


 

SAR Polarimetric Interferometry session

 

 

Question 1

POLInSAR was developed originally for tree height estimation. How mature is this product now and are there any gaps in the understanding of the performance of POLInSAR in different forest types? Is this the best way to get at biomass from radar coverage? There appear to be no saturation effects but how accurate is biomass from height and how robust are the allometric relations used?

 

Question 2

What are the prospects for exploiting POLInSAR using existing/near future satellite sensors? What are the key limitations on performance? Do we need to wait until the next generation of multi-satellite clusters? Are there sufficient programs in place to try and fully exploit POLInSAR for ALOS-PALSAR, Envisat ASAR, Radarsat II and Tandem-X?

 

Question 3

What is the role of full vs. partial polarimetry in POLInSAR products? Can dual pol systems be used for height/biomass estimation with wide swath coverage for example?

 

Question 4

What is the role of advanced signal processing issues based on coherence optimisation, coherent target decomposition etc. Are these crucial to product development or can simpler processing schemes based on standard linear polarisations, Pauli channels etc. be used just as well?

 

Question 5

What are the prospects for wide area vector tomographic imaging from space? Are there any fundamental problems in processing, data collection etc. or are the requirements well within the limits of existing technology and algorithm maturity? What would be the advantage of tomographic imaging over interferometry? What new products would emerge?

 

Question 6

What about exploiting polarimetry in differential or D-InSAR applications? Are there any clear application areas where this will be important? What extra performance can we expect to get for D-POLInSAR vs. classical D-InSAR systems?

 

 


Forestry Session

 

 

Question 1

Which are the most promising approaches for forest biomass estimation, and what are the limitations?

 

Question 2

Is it possible to estimate forest height with L- and/or P-band over tropical forest?

 

Question 3

Can we identify a set of forest types over which the different techniques should be tested, validated? Have tests being conducted over these types of forests? What are the estimated limits of each of the identified techniques over these different biotopes?

 

Question 4

Can we develop robust biophysical parameter retrieval techniques for complex targets such as heterogeneous, hilly and textured natural forests? What are the needed biophysical parameters? Biomass, tree height, forest density, bhd...?

 

Question 5

Most tests have been conducted with airborne data. Is this representative for spaceborne data? Is resolution an issue for this type of applications? Is the typically steeper spaceborne incidence angle a difficult issue?

 

Question 6

Tropical forests are disappearing at alarming rates. Could ENVISAT ASAR be utilized better to mitigate this problem?

 

 


Applications Session

 

 

Question 1

In each measurement, what kind of “unique” calibration and ground truth will be required?

 

Question 2

For further development of new technical approaches, what kind of validation data (which include SAR data, but also other physical measurements) should be needed? Are these data or measurements already available?

 

Question 3

Who should be involved in order to achieve the final aims of the developed technique?

 

Question 4

Is multi-frequency + polarimetry very important for future applications, and what would be the limitations and gains?

 

 


Land-agriculture applications session (update to follow)

 

Question 1

How do spatial resolution and revisit time affect the usefulness of SAR remote sensing data for agricultural application? Can recommendations be made for future missions or experiments, especially based on polarimetric interferometry?

 

Question 2

Is it still general opinion that X-band carries lower information content on agricultural areas compared to L-band and C-band?

 

Question 3

What is the relative importance of multi-frequency vs. polarimetric SAR/InSAR data for agricultural applications?

 

Question 4

In terms of importance for the agricultural application, in which order would you list the following items and their combinations: Spatial resolution, radiometric resolution, multifrequency, polarimetry, interferometry, revisit time?

 

Question 5

Are data fusion techniques (with reference both to multiple types of SAR images and multiple sensors) for the agricultural applications completely assessed? Would you consider useful to have an opportunity to compare techniques developed by different institutions in an open contest? (in which case what should be the rules to make it useful?)

 

 


Theoretical Modelling session

 

 

Question 1

Is there a benefit to introduce (more) physical modelling in algebraic modelling in POLInSAR ? How to link the two communities?

 

Question 2

How reliable are incoherent / coherent forest scattering models today in terms of polarimetric and interferometric observables at X, C, L and P bands? Where are the main limitations?

 

Question 3

What is the potential of coherent agriculture soil and vegetation modelling and where are the main limitations?

 

Question 4

Are the existing (coherent) ice scattering models capable for Pol-InSAR applications? What are the required developments?

 

Question 5

For mission operation design and performance analysis, data sets with relevant ground data are required for scattering modelling. How large and reliable are the existing data sets and how to make them available?

 

Question 6

What was the progress with respect to the recommendations of the PolinSAR 2003 WS about:

  • Modelling of vertical extinction in tree and forest canopies
  • Introduction of higher order scattering for soil surfaces
  • Polarisation behaviour of microwaves measurements of crops
  • Modelling of polarimetric phase difference in sea ice

 


Airborne campaigns session (update to follow)

 

 

Question 1

It there a need for an airborne campaign where multiple sensors collect Polarimetric Interferometric and/or Polarimetric data at multiple frequencies with associated in situ ground truth data for cross-calibration and algorithm comparisons purposes? What sites would be recommended for such studies?

 

Question 2

Can any significant gaps be identified in Polarimetric Interferometric and/or Polarimetric data sets for validation and development of existing and new techniques, i.e. is there a need for campaigns that fill these gaps for different applications (e.g. forest, hydrology, agriculture, and ice). If so, what applications, modes, frequencies, sites etc. would be recommended for such campaigns.

Question 3

Is there a need for Single Pass Polarimetric interferometric systems to help quantify the influence of temporal decorrelation on repeat pass results? If so what frequencies would be the most useful to implement?

 

Question 4

Are the geophysical or biological systems that would benefit from persistent polarimetric interferometric observations that may be possible with UAV type systems? What would be the desired operating characteristics of such a system?

 

Question 5

Are there synergistic opportunities for spaceborne/airborne joint campaigns similar to ones previously conducted for the ERS, JERS and SIR-C missions?

 

Question 6

Are there any new ideas about new Polarimetric Interferometric observation techniques, such as bi- and multistatic techniques and multi-frequency techniques that require new campaigns?

 

Question 7

Are there any new applications areas for Polarimetric Interferometry that requires new campaigns for proof of concept, demonstration and validation?

 

 

 


Spaceborne mission session

 

 

Question 1

What future missions have a great potential for Pol-InSAR applications? What recommendations can be given in this respect?

 

Question 2

POL-INSAR vs. "Single-pol multi-baseline" : POL-INSAR & "Single-pol multi-baseline" interferometry are different acquisitions configurations (for e.g. for DEM extraction over vegetated areas). What are the advantages/drawbacks of such architectures in the framework of spaceborne missions for vegetation studies?

 

Question 3

Spaceborne POL-INSAR for a global biomass product: Future spaceborne POL-INSAR missions are expected to provide global biomass estimation with an unprecedented accuracy. What accuracy range, in terms of altimetric & planimetric resolution, localisation, is necessary to allow new applications, in the field of biomass estimation (carbon cycle) ?

 

Question 4

POL-INSAR and bi-static effects: One possibility of achieving low-cost space-borne POL-INSAR missions is to use a constellation of low cost passive receivers in the vicinity of an illuminating SAR partner (cartwheel, pendulum, ... principles). In this case, the POL-INSAR acquisition is conducted under a bistatic configuration. What kind of alteration of the received signal is expected? If any, give recommendation on the maximum bistatic angle that can be accepted.

 

 

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