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'Field spectroscopy' is a general term describing a number of related techniques used to investigate the reflectance properties of Earth surface materials in-situ, normally under solar illumination. Most often, the aim is to measure the spectral reflectance of vegetation, soils, rocks or water bodies, in which case the term 'field spectrometry' is more appropriate. A purist might argue that 'field spectroradiometry' is better still, but the contraction of 'spectroradiometry' to 'spectrometry' is widely accepted and understood.

Field spectroscopy (FS) has many applications in remote sensing generally, but the focus of the material presented here is on its role in the calibration and validation of data for terrestrial applications. Within cal/val, FS is used to characterise ground targets for use in vicarious calibration and atmospheric correction, and to validate remote sensing measurements and models.

Reflectance geometry of the outdoor environment

Methods of field spectroscopy

Examples of instrument configurations used in field spectroscopy

Visualisation of directional reflectance factors

Further information

Progress in Field Spectroscopy (pdf, 3Mb)
A review of the subject, focusing on developments since the late 1980s. The paper describes the physical basis of the subject and evaluates the different methods and instruments which have been employed across a range of studies. The development and use of field goniometers is described, and related to methods for estimating the bidirectional reflectance distribution function (BRDF) from directional reflectance measurements in the field.

USGS Tutorial
Roger Clark and colleagues from the US Geological Survey have produced a very useful tutorial describing how they use field spectroscopy to perform atmospheric correction of AVIRIS data.

NERC Field Spectroscopy Facility
This facility is one of around 30 NERC Services, set-up to provide researchers in the UK with access to high-quality equipment and a source of advice and training in field spectroscopy. The facility is currently setting-up a calibration service for users.
Discussion forum hosted by Analytical Spectral Devices, manufacturers of the FieldSpec range of spectroradiometers.

Software for field spectroscopy and BRDF visualisation can be found on the Links page.

Creative Commons License
This work is licenced under a Creative Commons Licence.
Last updated 26/09/2008