The document proposes a hybrid approach to estimating biophysical parameters from remote sensing data that combines a theoretical forward model with available reference samples. It aims to improve both accuracy and robustness of estimates. The approach formulates the estimation problem and characterizes the deviation between model outputs and observations using reference samples. An experimental analysis applies the approach to soil moisture estimation using microwave data, demonstrating improved performance over solely using the theoretical model.

1. A Novel Hybrid Approach to the Estimation of Biophysical Parameters from Remotely Sensed Data Luca Pasolli1,2 Lorenzo Bruzzone1 Claudia Notarnicola2 E-mail:luca.pasolli@disi.unitn.it luca.pasolli@eurac.edu Web page: http://rslab.disi.unitn.it http://www.eurac.edu

2. 2 Outline Introduction and Motivation 1 Aim of the Work 2 Proposed Hybrid Estimation Approach 3 Experimental Analysis 4 Discussion and Conclusion 5 IEEE International Geoscience and Remote Sensing Symposium IGARSS 2011 Vancouver, Canada – 24-29 July, 2011

4. Supportformanyapplicationdomains:

5. Naturalresources management

7. Limitedavailabilityofprior information

8. FieldreferencesamplesIEEE International Geoscience and Remote Sensing Symposium IGARSS 2011 Vancouver, Canada – 24-29 July, 2011

10. Look Up Tables

15. site and sensor dependencyIEEE International Geoscience and Remote Sensing Symposium IGARSS 2011 Vancouver, Canada – 24-29 July, 2011

17. isbased on the integrationoftheoreticalforwardmodel and available (few) referencesampesREFERENCE SAMPLES THEORETICAL FORWARD MODEL Accuracy in specificdomains HYBRID ESTIMATION APPROACH Robustness and Generalization Ability IEEE International Geoscience and Remote Sensing Symposium IGARSS 2011 Vancouver, Canada – 24-29 July, 2011

18. 6 Proposed Approach: Problem Formulation General Estimation Problem Continuous Target Biophysical Variable Input Remotely Sensed Variables THEORETICAL FORWARD MODEL + INVERSION TECHNIQUE Desired Mapping Function Deviation Function REFERENCE SAMPLES HybridEstimationFunction IEEE International Geoscience and Remote Sensing Symposium IGARSS 2011 Vancouver, Canada – 24-29 July, 2011

19. 7 Proposed Approach: ProblemFormulation Example:EstimationProblemwithtwo Input Variables(x1,x2) Goal: To associate a target parameter estimate ŷ to each position of the input space TheoreticalForwardModel + InversionTechnique Available (few) ReferenceSamples 2-dimensional input space IEEE International Geoscience and Remote Sensing Symposium IGARSS 2011 Vancouver, Canada – 24-29 July, 2011

20. 8 Proposed Approach: Characterization of δ(.) Hypothesis:pointsclose in the input spacehavesimilarvaluesofδ(.) Idea:to exploit the deviationassociatedwith the availableReferenceSamples 2-dimensional input space IEEE International Geoscience and Remote Sensing Symposium IGARSS 2011 Vancouver, Canada – 24-29 July, 2011

21. 8 Proposed Approach: Characterization of δ(.) Hypothesis:pointsclose in the input spacehavesimilarvaluesofδ(.) Idea:to exploit the deviationassociatedwith the availableReferenceSamples Case I: VeryFewReferenceSamples Global DeviationBias (GDB) Strategy δ(.) isapproximatedwith a constantvalue in the whole input space 2-dimensional input space IEEE International Geoscience and Remote Sensing Symposium IGARSS 2011 Vancouver, Canada – 24-29 July, 2011

24. 9 Proposed Approach: Implementation Training Phase REFERENCE SAMPLES Characterizationofδ(.) Operational Estimation Phase + IEEE International Geoscience and Remote Sensing Symposium IGARSS 2011 Vancouver, Canada – 24-29 July, 2011

26. High spatial and temporalvariabilityof the target parameter

27. Sensitivityof the microwavesignaltomanydifferent target properties

30. C-Band (5.3 GHz)

31. Dual-polarization (HH and VV)

32. Multi-angle (23° - 40°)

33. Fieldmeasurementsofsoilparameters

34. Soilmoisture/dielectricconstant (5 < ε< 15)

35. Soilroughness (1.3 < σ< 2.5 cm)IEEE International Geoscience and Remote Sensing Symposium IGARSS 2011 Vancouver, Canada – 24-29 July, 2011 10

38. Cross Validation procedure

39. Evaluationof quantitative qualitymetrics

40. RootMeanSquaredError (RMSE)

41. CorrelationCoefficient (R)

42. Slope and Interceptof the lineartendencylinebetweenestimated and measured target values[1]L. Pasolli, C. Notarnicola and L. Bruzzone, “EstimatingSoilMoisturewith the SupportVectorRegressionTechnique,” IEEE Geoscience and Remote SensingLetters, in press IEEE International Geoscience and Remote Sensing Symposium IGARSS 2011 Vancouver, Canada – 24-29 July, 2011

43. 12 Results: Experiment 1 HP:VeryFew ReferenceSamples Influenceof the # ofReferenceSamplesAvailable Proposed HybridEstimationApproach (GDB Strategy) Standard TheoreticalForwardModel Inversion 2-dimensional Input Space IEEE International Geoscience and Remote Sensing Symposium IGARSS 2011 Vancouver, Canada – 24-29 July, 2011

44. Proposed HybridEstimationApproach (LDB Strategywith fixedlocalneighborhood) Standard TheoreticalForwardModel Inversion 13 Results: Experiment 2 HP:Few ReferenceSamples 2-dimensional Input Space IEEE International Geoscience and Remote Sensing Symposium IGARSS 2011 Vancouver, Canada – 24-29 July, 2011

50. Itiscapabletohandle the variabilityof the deviationδ(.)in the input space domain

52. Investigationof the proposedappraoch in otherchallengingapplicationdomainsIEEE International Geoscience and Remote Sensing Symposium IGARSS 2011 Vancouver, Canada – 24-29 July, 2011 15

53. A specialThankto Dr. Claudia Notarnicola and Prof. Lorenzo Bruzzone Thankyoufor the Attention!! Questions? luca.pasolli@disi.unitn.it luca.pasolli@eurac.edu IEEE International Geoscience and Remote Sensing Symposium IGARSS 2011 Vancouver, Canada – 24-29 July, 2011

55. L-Band (0.44 GHz)

56. Dual-polarization (HH and VV)

57. Acquisition angle 40°

58. Fieldmeasurementsofsoilparameters

59. Soilmoisture/dielectricconstant (5 < ε< 16)

60. Soilroughness (1.3 < σ< 2.5 cm)Standard TheoreticalForwardModelInversion ProposedHybridApproach (LDB) ProposedHybridApproach (GDB) IEEE International Geoscience and Remote Sensing Symposium IGARSS 2011 Vancouver, Canada – 24-29 July, 2011