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Bio-optical data: best practice and legacy datasets

 

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Project overview


Data from spectroradiometers and related surface-based optical instrumentation plays an important role in the calibration and validation (cal/val) of image data from remote sensing missions and will play a key role in the validation efforts in TERN AusCover. Stimulated by TERN and related international initiatives (e.g. FluxNet, SpecNet, NEON) there has been increased interest in archives for the reuse and exchange of spectral datasets and reference spectral data. However, whilst ‘spectral libraries’ or ‘spectral databases’ place an emphasis on organisation, storage and retrieval, they also raise issues of quality and the representativeness of the data they contain for subsequent re-use. Field measurement practices vary and, in the absence of agreed best practice guides, user experience is often a key guide to data quality. We submit that well documented metadata is fundamental to both the establishment of best practice and criteria for quality assessment; these metadata document the conditions (meteorological, geometrical, physical) under which the measurements were obtained, details about the object measured, and instrument performance (radiometric and spectral checks) as well as any subsequent processing undertaken on the data.

 

To date there are no national or international standards for in situ spectral measurement or management of such data in environmental applications, without which quality cannot be universally assessed. The time is right to propose such international standards. Stimulated by TERN we propose to bring together key Australian and international experts in field spectroscopy, cal/val and data-warehousing for a workshop to assess current practice, establish future best practice, and to establish long-term directions for the exchange of bio-optical and related metadata. The key outcome will be an international journal paper which proposes a new, tested standard for international adoption.

 

Measurement of grapevine canopy reflectance using hand-held field of view

 

Measurement of coral reflectance in shallow water coastal environments

 

For enquiries about this project please contact the Principal Investigator, This e-mail address is being protected from spambots. You need JavaScript enabled to view it

 


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Workshop Report (18-22 June 2012)


Our first meeting drew on expertise in a wide range of applications of field spectroscopy (including inland and marine, geological, vegetation) as well as in instrumentation and calibration and of the use of spectroradiometers in validation of other remote sensing datasets. Importantly, the meeting also drew on expertise in informatics, specialist databases and metadata to consider how best archiving and exchange systems might best be designed. This expertise was drawn both internationally and from Australia.

The meeting was seen as very timely given a number of parallel international and national perspectives that are leading to widespread recognition of the need for better tools to manage spectral datasets; datasets which are often of high value but are not easily discoverable.

The following experts were present at the workshop.

Name Institution Role / Expertise
Tim Malthus CSIRO Division of Land and Water, Canberra PI, field spectroscopy, calibration and validation
John Gamon University of Alberta, Canada Convenor of SpecNet community
Phil Townsend University of Wisconsin, USA Vegetation spectroscopy
Chris MacLellan NERC Field Spectroscopy Facility, University of Edinburgh, UK Calibration and validation
Andy Hueni RSL, University of Zurich, Switzerland Writer of SPECCHIO software
Alfredo Huete University of Technology Sydney Spectroscopy for phenological studies
Laurie Chisholm University of Wollongong Field spectroscopy
Simon Jones Royal Melbourne Institute of Technology Vegetation spectroscopy
Stuart Phinn University of Queensland Terrestrial and aquatic spectroscopy
Cindy Ong CSIRO Earth Science and Resource Engineering, Perth Geological and mineral spectroscopy
Barbara Rasaiah Royal Melbourne Institute of Technology Metadata and informatics (PhD student)
Chris Roelfsma University of Queensland Aquatic spectroscopy
Lola Suarez Royal Melbourne Institute of Technology Remote sensing of vegetation
Rebecca Trevithick Department of Science, Information Technology,
Innovation and the Arts, Queensland
Informatics and data archiving
Matthew Wyatt IVEC, Western Australia Metadata and informatics
Carlos Aya Intersect, NSW Senior IT developer



The aims of the workshop were to drive best practice in field measurement and to lay the foundations for an international standard approach for the exchange of spectral datasets. Critical questions that were discussed were:

- What are the key criteria for assessing the quality and robustness of a spectral signature obtained in the field?
- What are the key components that lead to the acquisition of high quality spectra in the field?
- What is the best means by which the spectrum and its metadata can be exchanged and stored to preserve its quality and robustness?



Through four and a half days of presentations, breakout groups and general discussion, the meeting focused initially on agenda setting, then on metadata and informatics solutions to arrive at a synthesis and identification of next steps. Metadata were recognized as the key to long-term usage and sharing of field spectral data. However, standards to ensure quality in data collection are required to facilitate accurate cross comparison of data from different studies; currently there is no international backbone that ensures this.

It was recognized that a careful balance needed to be struck between three key factors: the diversity of studies undertaken using field spectroscopy, the diversity of instrumentation used and the need for some strictness in standards to ensure data quality and legacy value. Any standards developed also need to build in flexibility to cope with new innovations in the technology.

The meeting was highly successful in forming an outline of best practice to improve data collection in the field. Through breakout sessions, the group began the identification of core metadata requirements for a number of different applications (soils, underwater spectra and vegetation). A variety of methods to both exchange and store spectral data were presented and discussed as were novel tools to assist in summarising the completeness and quality of such datasets. It was recognized that tools are required to help ease the burden of input of metadata. The role of peer review in determining quality was also discussed. The need for care in the preparation of field protocols and of recording data in the field was widely recognized.

The meeting agreed that with modifications, the SPECCHIO software could meet international objectives to solve the problem. It is intended meeting outcomes will be communicated via a proposal to publish a special issue of an international remote sensing journal on field spectroscopy in support of remote sensing studies.

click to enlarge
back row l-r: Chris Roelfsema, John Gamon, Phil Townsend, Andreas Hueni, Matt Wyatt, Carlos Aya, Simon Jones, Tim Malthus.  Front row l-r: Alfredo Huete, Cindy Ong, Chris MacLellan, Rebecca Trevithick, Lola Suarez, Laurie Chisholm, Barbara Rasaiah. Absent: Stuart Phinn

 

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Last Updated on Sunday, 08 February 2015 16:06