Radiometric Calibration of a Dual-Wavelength, Full-Waveform Terrestrial Lidar
Abstract
:1. Introduction
2. Physical Background
2.1. Basic Lidar Equation for Forest Canopies
2.1.1. Apparent Reflectance
2.1.2. Physical Interpretation of Apparent Reflectance
2.1.3. Telescope Efficiency
2.2. Recorded Return Waveforms and Apparent Reflectance
2.2.1. Recording Return Waveforms
2.2.2. Modeling Return Waveforms
3. Instrument and Data Preprocessing
3.1. The Dual Wavelength Echidna Lidar
3.1.1. Internal Calibration Objects
3.1.2. Signal Recording and System Response
3.2. Preprocessing of DWEL Waveform Data
Saturation Correction
4. Radiometric Calibration Procedures
4.1. Calibration Model Setup
4.2. Calibration Data Collection
4.3. Calibration Model Fitting
5. Results and Discussion
5.1. Radiometric Calibration
5.1.1. Fitting of the Semi-Empirical Model
5.1.2. Apparent Reflectance Error and Its Sensitivity to Intensity and Range
5.2. Calibration Comparison of the Two Wavelengths
6. Conclusions
Acknowledgments
Author Contributions
Conflicts of Interest
Appendix A
A1. Area Scattering Phase Function for Lambertian Facets of the Same Diffuse Reflectance
A2. Error in Apparent Reflectance from Two Sources: Range and Return Intensity
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Range (m) | Range Interval (m) | Measurement Positions |
---|---|---|
[0.5, 10] * | 0.5 | 20 |
(10, 15] | 1 | 5 |
(15, 40] | 5 | 5 |
(40, 70] | 10 | 3 |
Target | NIR Reflectance | SWIR Reflectance | Dimension (cm by cm) | ||
---|---|---|---|---|---|
Measured 1 | 2 | Measured 1 | 2 | ||
White Spectralon panel 3 | 0.99 | 0.98 | 30.5 × 30.5 | ||
Gray Painted Panel 1 | 0.436 | 0.574 | 0.349 | 0.447 | 38.0 × 30.5 |
Gray Painted Panel 2 | 0.320 | 0.431 | 0.245 | 0.329 | 38.0 × 30.5 |
Parameter | Wavelength | |
---|---|---|
1064 nm | 1548 nm | |
C0 | 5788.265818 | 22,054.218342 |
C1 | 0.000319 | 0.000319 |
C2 | 0.808880 | 0.540762 |
C3 | 25,176.835032 | 25,176.835032 |
b | 1.384297 | 1.585985 |
Wavelength | 1064 nm | 1548 nm | |
---|---|---|---|
Measured vs. Modeled Intensity, Adjusted | Training 1 | 0.954 | 0.983 |
Validation 2 | 0.948 | 0.964 | |
RMSE of Apparent Reflectance | Training 1 | 0.108 | 0.092 |
Validation 2 | 0.081 | 0.064 |
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Li, Z.; Jupp, D.L.B.; Strahler, A.H.; Schaaf, C.B.; Howe, G.; Hewawasam, K.; Douglas, E.S.; Chakrabarti, S.; Cook, T.A.; Paynter, I.; et al. Radiometric Calibration of a Dual-Wavelength, Full-Waveform Terrestrial Lidar. Sensors 2016, 16, 313. https://doi.org/10.3390/s16030313
Li Z, Jupp DLB, Strahler AH, Schaaf CB, Howe G, Hewawasam K, Douglas ES, Chakrabarti S, Cook TA, Paynter I, et al. Radiometric Calibration of a Dual-Wavelength, Full-Waveform Terrestrial Lidar. Sensors. 2016; 16(3):313. https://doi.org/10.3390/s16030313
Chicago/Turabian StyleLi, Zhan, David L. B. Jupp, Alan H. Strahler, Crystal B. Schaaf, Glenn Howe, Kuravi Hewawasam, Ewan S. Douglas, Supriya Chakrabarti, Timothy A. Cook, Ian Paynter, and et al. 2016. "Radiometric Calibration of a Dual-Wavelength, Full-Waveform Terrestrial Lidar" Sensors 16, no. 3: 313. https://doi.org/10.3390/s16030313
APA StyleLi, Z., Jupp, D. L. B., Strahler, A. H., Schaaf, C. B., Howe, G., Hewawasam, K., Douglas, E. S., Chakrabarti, S., Cook, T. A., Paynter, I., Saenz, E. J., & Schaefer, M. (2016). Radiometric Calibration of a Dual-Wavelength, Full-Waveform Terrestrial Lidar. Sensors, 16(3), 313. https://doi.org/10.3390/s16030313