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					Calibration and validation of
      satellite sensors

       Sharlene-Asia Naicker
         Maanda Rambau
       Sedzani Elia Muravha
         Amanda Forbes
         Busisiwe Nkuzani

                                1
                    Overview
 Introduction
 Definition and importance
 Technology trends
 Challenges
 Best practices
 Career scope
 Conclusion
 Questions
 Bibliography




                               2
                     Definition
   Calibration:
    • Validation of specific techniques and
      measurements of equipment.
    • Comparison of measurements with a known
      standard or other devices.
    • Scientifically assessing a systems response to
      known controlled signal inputs.
    • Responses that are traceable to Cal/Val
      standards.


                                                       3
                       Definition
   Validation:

    •   Product and process that conforms to the
        necessary user requirements and
        specifications.

    •   Process of assessing the quality data that is
        derived a systems output.




                                                        4
                    Importance
   Building blocks of all satellites programs.
   Data from different sensors are processed.
   Reliability and possibility of uncertainties are
    established.
   Needed for airborne, space borne, images and
    data retrieval.
   Can be done in a shuttle or on a satellite.
   Instruments performance and calibration
    accuracy.

                                                       5
                  Importance
   Needed to be done:

    • Pre-launch: data to be accurate and reliable.
    • In-orbit: High temporal resolution and prior
      data acquisition.
    • Post-launch: Using in-situ measurements and
      provide reference data for future calibration
      and validation measurements.



                                                  6
                   Importance
   Generate consistent and accurate data.
   To determine progress of validation.
   One kind of calibration is enough.
   Techniques such as relative and absolute which
    use uniform spatial radiance are efficient.
   Technically demanding but require international
    standards.
   Data quality, competency and aid detection
    methods.

                                                      7
                    Importance
   Both provide consistency, reliability, quality and
    availability.
   Biological, geological, environmental sciences.
   Habitat change, biodiversity, vegetation,
    mapping are significant.
   Confidence in data that is well calibrated and
    validated and provide traceability
   Inter-comparison and long term studies and
    product specifications are achieved.

                                                         8
 The challenges facing calibration and
              validation
 General Challenges
 Lack of funding
 Technical challenges
 Lack of resources
 Lack of regular comparison of instrumentation and
  methodologies.
 Lack of endorsement and support.
 Lack of framework development, guideline
  standards, best practices and recommendations.


                                                      9
    The challenges facing calibration and
                 validation
Calibration challenges:

   Pre-launch calibration:
     • Reproducing the essential features of the space
       environment.
     • Vibration, extreme temperatures and
       contamination.
     • Changes in time.
     • Radiometric produces uncertainty and cost and
       spatial invariance or broad land coverage.

                                                     10
 The challenges facing calibration and
              validation
 Calibration challenges:
 On board calibration
   • The full field view of the sensor is not available.
   • The accuracy is not as high as pre-launch
      calibration.
 Vicarious calibration
   • The target might not be homogenous or easily
      accessible.
   • The size and complexity of the mission is
      increased.
                                                           11
    The challenges facing calibration and
                 validation
Calibration challenges:

   Post-launch calibration
     • Platform may be damaged or degraded in time.
     • Uncertainty in reliability by neglecting a
       measurement.
     • Atmospheric characteristics.
     • Human errors.




                                                      12
    The technology trends in calibration
              and validation

   Three things that need to be done to improve the
    technology for the calibration and validation
    process:

    •   Instrument Calibration
    •   Instrument Validation
    •   Instrument Re-qualifications




                                                       13
    The technology trends in calibration
              and validation
   Instruments
     • Integrating Sphere




                                           14
    The technology trends in calibration
              and validation
   Inexpensive Near-IR Sunphotometer




                                           15
               Best Practices

   CEOS
   WGCV
   Quality Assurance Framework for Earth
    Observation (QA4EO)




                                            16
                  QA4EO
   7 Guidelines on Data Quality




                                   17
                       QA4EO
   2 Guidelines on Data Policy
    •   Guidelines on how to document the data and
        how to exchange the data

          DPK001 : Procedures and Policies
         • DPK002: Metadata Requirements




                                                     18
                     QA4EO
   1 Guideline on Communication and
    Education
       CEK001
        • Peer review
        • Common Terminology
        • Cal/Val Portal




                                       19
                     IVOS
   Chaired by Nigel Fox
   Mission is to monitor the quality of data
    from Infrared and Visible Optical Earth
    Observation Satellites through the quality
    of calibration and validation and
    international collaboration



                                                 20
   Where to study for CalVal
University of Stellenbosch
University of Cape Town
University of Johannesburg
University of KZN
University of Limpopo
University of Fort Hare
University of Venda

                               21
University of South Africa
University of Free state
Nelson Mandela Metropolitan
Rhode University
Wits University
University of Pretoria
North –West University
                               22
            Career Scope
Studying    Cal/Val can bring different
career opportunities since it is a broad
field that includes the following:

•Geoinformation Specialist
•Image processing researcher
•GIS researcher
•Space science facilitator

                                           23
Electronic  technologist or engineer
Software engineer
Electronic engineer
Satellite system engineer
Control system engineer
Mechanical engineer
Electrical engineer
Remote sensing researcher


                                        24
               Conclusion
   Cal/Val is becoming the most important
    part of the remote sensing process.
   More research and awareness campaigns
    are required.




                                         25
                Thank you
   Ms M Lubbe
   Mr L Vhengani
   Dr M Lysko
   Mr D Griffith
   Patricia Govender
   CSIR
   DST
   Everyone that has helped us.

                                   26
              Bibliography


Fullbibliography is available in the final
report submitted.




                                              27

				
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posted:11/1/2011
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