Calibration and validation of satellite sensors

1
Calibration and validation of satellite sensors

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

2
Overview

• Introduction
• Definition and importance
• Technology trends
• Challenges
• Best practices
• Career scope
• Conclusion
• Questions
• Bibliography

3
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.

4
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.

5
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.
  

6
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.

7
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.

8
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.

9
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.

10
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.

11
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.

12
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.

13
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

14
The technology trends in calibration and
validation

• Instruments
• Integrating Sphere

15
The technology trends in calibration and
validation

• Inexpensive Near-IR Sunphotometer

16
Best Practices

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

17
QA4EO

• 7 Guidelines on Data Quality

18
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

19
QA4EO

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

20
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

21
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

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• University of South Africa
• University of Free state
• Nelson Mandela Metropolitan
• Rhode University
• Wits University
• University of Pretoria
• North West University

23
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

24

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

25
Conclusion

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

26
Thank you

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

Thank you for your attention. Any Questions???
27
Bibliography

• Full bibliography is available in the final
  report submitted.