ASDToolkit: A Novel MATLAB Processing Toolbox for ASD Field Spectroscopy Data
Abstract
:1. Introduction
2. Description of ASDToolkit
2.1. Theoretical Background
2.2. Overview of the ASD FieldSpec 3 and Data Acquisition
2.3. Overview of ASDToolkit
2.4. Preparation of ASD Data Files
2.5. Required User Files
- (1)
- The file must be a .csv;
- (2)
- The first row in the first column must contain a panel identifier or panel characteristic file name;
- (3)
- The wavelengths must only be in the first column, beginning at row two;
- (4)
- The panel measurement data must only be in the second column, beginning at row two;
- (5)
- The panel measurements must be provided at the same wavelength intervals as the Rratio files.
2.6. Description of User Inputs to the ASDToolkit Interface
3. Methodology
3.1. ASDToolkit Workflow
- Import necessary reflectance files [29]
- Inputs: ASD data files;
- Outputs: ASD relative reflectance data, header information (time, date, wavelength, etc.).
- Calculate the solar zenith angles
- Inputs: ASD data file header information (date, time), latitude/longitude information, hours offset from UTC;
- Outputs: Solar azimuth angle, solar zenith angle.
- Import panel-specific values for R(0°:45°)
- Inputs: Reference panel characteristic files (pre-defined or user supplied);
- Outputs: Panel characteristic information.
- Import nBCRF polynomial coefficients
- Inputs: Panel-independent BCRF (0°:45°);
- Outputs: nBCRF polynomial parameters.
- Polynomial expansion
- Inputs: Panel-specific BCRF (0°:45°), solar geometry data, nBCRF polynomial parameters;
- Outputs: Polynomial expansion results adjusted for normalized BCRF.
- Calculate the corrected solar zenith angle panel values
- Inputs: Average polynomial expansion results, solar geometry data;
- Outputs: (0°:SZA°) adjusted reference panel BCRF spectra for the given panel.
- Calculate estimated absolute reflectance
- Inputs: SZA-adjusted panel BCRF, ASD relative reflectance data;
- Outputs: Estimated absolute reflectance values.
- Apply IACF or not
- Inputs: Solar zenith angle of reference measurement, solar zenith angle of target measurement;
- Outputs: Estimated absolute reflectance values with IACF applied.
- Apply discontinuity correction
- Inputs: Estimated absolute reflectance values;
- Outputs: Estimated absolute reflectance values with correction applied.
- Export results
- Inputs: Estimated absolute reflectance data structure;
- Outputs: Header file, estimated absolute reflectance data structure (as a MATLAB file and an Excel file), IACF file, discontinuity correction files (additive and multiplicative solutions).
3.2. ASDToolkit Output Files
- variablename.mat: A MATLAB® (*.mat) data file that contains all the processed data and header information and can be opened directly in MATLAB® for further data manipulation.
- variablename_estimatedAbsoluteReflectance.csv: A (*.csv) file that contains the estimated absolute reflectance output values where each column represents a single data file, with the name of the file as the first row in each column.
- variablename_headerInfo.csv: A (*.csv) file that contains the detailed header information for each processed file, where each column represents a single data file that was processed.
- variablename_estimatedAbsoluteReflectance_IACF.csv: Generated when the IACF option is selected in the interface. A (*.csv) file that contains the estimated absolute reflectance output values with the IACF applied, where each column represents a single data file, with the name of the file as the first row in each column.
- variablename_DC_additive.csv: Generated when the Discontinuity Correction option is selected in the interface. A (*.csv) file that contains the estimated absolute reflectance values for the additive solution, where each column represents a single data file, with the name of the file as the first row in each column.
- variablename_DC_multiplicative.csv: Generated when the Discontinuity Correction option is selected in the interface. A (*.csv) file that contains the estimated absolute reflectance values for the multiplicative solution, where each column represents a single data file, with the name of the file as the first row in each column.
3.3. Details on the Generated MATLAB® Data File (*.mat)
4. User Notes
5. Conclusions
Supplementary Materials
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Characteristic | Range |
---|---|
Spectral range | VNIR: 350–1050 nm |
SWIR1: 1000–1800 nm | |
SWIR2: 1800–2500 nm | |
Spectral resolution | 3 nm FWHM at 700 nm |
10 nm FWHM at 1400 and 2100 nm | |
Sampling interval | 1.4 nm at 350–1050 nm |
2 nm at 1000–2500 nm | |
No. of optical fibers | VNIR: 19 fibers (100 µm) |
SWIR1-2: 38 fibers (200 µm) |
Panel Identifier | Original (8°:h) Calibration | NRC 0°:45° Calibration Date(s)(yy-mm-dd) | Usage Type |
---|---|---|---|
IRBV-01 | June 2018 | 19-04-26 | Field use |
IRBV-02 | June 2018 | 19-04-26 | New |
McGill-03 | March 2013 | 18-10-02 16-06-16 | Field use |
NRC-01 | March 2011 | 16-06-17 | Field use |
NRC-02 | February 2012 | 16-06-16 | Primary lab 2012–2016 Field use 2016–ongoing |
UBC-01 | June 2006 | 19-04-26 | Field use |
Field Name | Description |
---|---|
path | Directory path of the input files |
name | Name of the input files |
header | Original ASD header information for the imported files |
datetime | Date and time information for the imported files |
panel | Filename of panel characteristic file |
latitude | Input latitude value |
longitude | Input longitude value |
elevation | Input elevation value |
reference_zenith | Calculated solar zenith angle for the reference measurement |
reference_azimuth | Calculated solar azimuth angle for the reference measurement |
target_zenith | Calculated solar zenith angle for the target measurement |
target_azimuth | Calculated solar azimuth angle for the target measurement |
wavelength | An array of type “Double” that contains the wavelength intervals for the imported files |
reflectance | An array of type “Double” that contains the estimated absolute reflectance values for the imported files |
IACF | Calculated IACF value for a given file |
IACF_reflectance | An array of type “Double” that contains the estimated absolute reflectance values with the IACF applied |
DC_additive | An array of type “Double” that contains the additive solution for the ASD discontinuity correction |
DC_multiplicative | An array of type “Double” that contains the multiplicative solution for the ASD discontinuity correction |
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Share and Cite
Elmer, K.; Soffer, R.J.; Arroyo-Mora, J.P.; Kalacska, M. ASDToolkit: A Novel MATLAB Processing Toolbox for ASD Field Spectroscopy Data. Data 2020, 5, 96. https://doi.org/10.3390/data5040096
Elmer K, Soffer RJ, Arroyo-Mora JP, Kalacska M. ASDToolkit: A Novel MATLAB Processing Toolbox for ASD Field Spectroscopy Data. Data. 2020; 5(4):96. https://doi.org/10.3390/data5040096
Chicago/Turabian StyleElmer, Kathryn, Raymond J. Soffer, J. Pablo Arroyo-Mora, and Margaret Kalacska. 2020. "ASDToolkit: A Novel MATLAB Processing Toolbox for ASD Field Spectroscopy Data" Data 5, no. 4: 96. https://doi.org/10.3390/data5040096