Unclassified/Unlimited
Earth Satellite Corporation
email: jsalisbury1@cfl.rr.com
April 23, 1998
Funded by the Defense Intelligence Agency Central Measurement and Signature Intelligence (MASINT) Office (CMO). Sponsored by Paul Lewis, Chairman, SPectroRAdiometric Working Group (SPRAWG)
This web site gives the executive summary and table of contents for the Field Guide. For a copy of the guide, contact John Salisbury (email to jsalisbury1@cfl.rr.com).
Because of the rapid advance of airborne and satellite sensor technology in providing higher spectral resolution over progressively broader wavelength regions, there is a need for more (and more accurate) field measurements to complement overhead data. The purpose of this field guide is to facilitate such ground-based measurements, first through a review of the environmental factors affecting such measurements, second through an evaluation of the instrumentation involved, and third through a suggested approach to the measurement process.
In evaluating environmental factors affecting spectral measurements in the field, the sources of radiance from a target are discussed in both the reflectance and emittance regions of the spectrum, as well as how those sources are modified by atmospheric attenuation and scattering, and the presence of clouds and wind.
Another factor affecting all spectral measurements in the field is the computer typically used for instrument control and data storage. Computers tend to be the universal weak link in field spectrometers, because of their typical low tolerance for bright sunlight, temperature extremes, windblown dust, and rain. Various solutions to the computer problem are discussed, including the acquisition of hardened computers.
The most commonly used field spectrometers are described, with advice on how to get the most out of each instrument. Then the pros and cons of each instrument are discussed with regard to different applications.
Finally, how to approach field measurements is described, beginning with a thorough testing of a field instrument (and the field instrument user) in the laboratory. Approaches to data collection, record keeping, data reduction, and data analysis are discussed. A major conclusion is that much greater support for data analysis is necessary to reach the full potential of spectroscopic remote sensing for target identification.
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1.0 INTRODUCTION |
1 |
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2.0 BACKGROUND |
2 |
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2.1 Environmental Factors Affecting Reflectance Measurements |
2 |
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2.1.1 Primary Source of Irradiance |
2 |
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2.1.2 Atmospheric Attenuation |
2 |
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2.1.3 Secondary Sources of Radiance |
7 |
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2.1.4 Clouds |
9 |
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2.1.5 Wind |
11 |
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2.2 Environmental Factors Affecting Emittance Measurements |
11 |
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2.2.1 Primary Source of Radiance |
11 |
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2.2.2 Atmospheric Attenuation |
13 |
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2.2.3 Secondary Sources of Radiance |
15 |
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2.2.4 Clouds |
17 |
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2.2.5 Wind |
18 |
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2.3 Other Factors Affecting Measurements |
19 |
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2.3.1 Computers - The Universal Weak Link |
19 |
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3.0 INSTRUMENTS OF THE REFLECTIVE REGION |
21 |
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3.1 General |
21 |
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3.2 FieldSpec® FR by Analytical Spectral Devices |
22 |
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3.2.1 Instrument Description |
22 |
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3.2.2 Instrument Tips and Rules of Thumb |
25 |
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3.3 GER 3700 by Geophysical and Environmental Research Corp. |
28 |
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3.3.1 Instrument Description |
28 |
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3.3.2 Instrument Tips and Rules of Thumb |
32 |
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3.4 GER MARK V by Geophysical and Environmental Research Corp. |
35 |
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3.4.1 Instrument Description |
35 |
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3.4.2 Instrument Tips and Rules of Thumb |
38 |
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3.5 PIMA II by Integrated Spectronics Pty. Ltd. Of Australia (U. S. Source is Spectral International, Inc. of Arvada, CO) |
39 |
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3.5.1 Instrument Description |
39 |
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3.5.2 Instrument Tips and Rules of Thumb |
42 |
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3.6 Pros and Cons of instruments in the Reflective Region |
43 |
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3.6.1 Fast Single Beam Instruments - FieldSpec® FR vs. GER 3700 |
43 |
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3.6.2 Double Beam Instrument - The GER Mark V |
45 |
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3.6.3 Active Measurement - The PIMA II |
46 |
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4.0 Instruments for the Thermal Region |
47 |
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4.1 General |
47 |
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4.2 The MD 104 by Bomem, Inc. of Quebec, Canada |
47 |
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4.2.1 Instrument Description |
47 |
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4.2.2 Instrument Tips and Rules of Thumb |
47 |
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4.3 The MicroFTIR by Designs and Prototypes, Inc. |
54 |
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4.3.1 Instrument Description |
54 |
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4.3.2 Instrument Tips and Rules of Thumb |
57 |
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4.4 Pros and Cons of Instruments in the Emittance Region |
59 |
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5.0 MEASUREMENT PROTOCOL |
61 |
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5.1 General |
61 |
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5.2 First and Foremost, Know Your Instrument |
61 |
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5.2.1 Reflectance Region |
62 |
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5.2.2 Emittance Region |
66 |
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5.3 Data Collection - Recognizing Environmental Effects |
70 |
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5.3.1 Reflectance Region |
70 |
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5.3.2 Emittance Region |
72 |
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5.4 Record Keeping |
75 |
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5.5 Data Reduction - Making Raw Data Useful |
76 |
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5.5.1 Reflectance Region |
76 |
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5.5.2 Emittance Region |
76 |
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5.6 Data Analysis |
79 |
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6.0 ACKNOWLEDGMENTS |
81 |
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7.0 REFERENCES |
82 |
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APPENDIX A GLOSSARY OF TERMS |
85 |
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