Regional Tropical Aboveground Biomass Mapping with L-Band Repeat-Pass Interferometric Radar, Sparse Lidar, and Multiscale Superpixels
Abstract
:1. Introduction
2. Materials
2.1. Canopy Cover Map
2.2. AGB Reference Map
2.3. SAR Products
2.3.1. Backscatter
2.3.2. Coherence
3. Methodology for AGB Mapping
3.1. Generating Features from Multiscale Superpixels
3.2. Training and Validation: Simulating Regional Calibration with GEDI
4. Results and Discussion
4.1. Results with a Low Biomass Mask
4.2. Training on the Entire AGB Range
4.2.1. Coherence and AGB
4.2.2. Multiscale Superpixels
4.3. Inspecting Model Importances
5. Conclusions and Future Work
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
Abbreviations
AGB | Above Ground Biomass |
ALOS-2 | Advanced Land Observing Satellite-2 |
GEDI | Global Ecological Dynamics Investigation |
GLAS | Geoscience Laser Altimeter System |
ICESat-1/-2 | Ice, Cloud, and land Elevation Satellite-1/-2 |
NISAR | NASA-ISRO Synthetic Aperture Radar |
PALSAR-2 | Phased Array type L-band Synthetic Aperture Radar 2 |
RMSE | Root Mean Squared Error |
RTC | Radiometric Terrain Correction |
SAR | Synthetic Aperture Radar |
TV Denoising | Total Variation Denoising |
UAVSAR | Uninhabited Aerial Vehicle Synthetic Aperture Radar |
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Sensor | Site | (Mg/ha) | (Mg/ha) | (%) | (Mg/ha) | (Mg/ha) | (Mg/ha) | (Mg/ha) | (%) |
---|---|---|---|---|---|---|---|---|---|
PALSAR-2 | Lope | 380.10 | 130.42 | 34.31 | 399.20 | 104.06 | 29.69 | 29.89 | 5.17 |
Mondah | 137.06 | 146.97 | 107.23 | 271.63 | 115.59 | 24.77 | 27.51 | 54.51 | |
Ogooue | 286.95 | 123.51 | 43.04 | 310.50 | 102.06 | 45.88 | 31.73 | 8.90 | |
UAVSAR | Lope | 332.55 | 159.51 | 47.97 | 382.99 | 107.70 | 27.86 | 29.33 | 14.20 |
Mondah | 125.03 | 142.58 | 114.04 | 271.55 | 110.16 | 23.20 | 27.13 | 59.00 | |
Ogooue | 256.37 | 137.97 | 53.82 | 302.04 | 103.55 | 37.54 | 31.37 | 17.27 |
Coherence First Date | Backscatter Image Date | Temporal Baseline | Area | SRTM Normal Angle | HV | Coherence | ||
---|---|---|---|---|---|---|---|---|
Sensor | Site | (ha) | () | () | () | |||
PALSAR-2 | Lope | 2015-03-12 | 2015-03-12 | 14 days | 7,521 | 9.1 (6.0) | −12.4 (3.5) | 0.34 (0.14) |
Mondah | 2015-04-14 | 2015-04-14 | 14 days | 2479 | 3.3 (3.2) | −13.8 (7.9) | 0.32 (0.18) | |
Ogooue | 2015-06-04 | 2015-06-18 | 14 days | 5735 | 6.2 (5.2) | −12.8 (4.1) | 0.59 (0.11) | |
UAVSAR | Lope | 2016-02-25 | 2016-03-08 | 2 h | 2150 | 7.5 (5.5) | −13.6 (5.8) | 0.86 (0.1) |
Mondah | 2016-03-06 | 2016-03-02 | 2 h | 1170 | 3.2 (3.2) | −15.3 (10.4) | 0.73 (0.35) | |
Ogooue | 2016-02-27 | 2016-02-27 | 8 days | 5627 | 5.5 (4.5) | −13.6 (9.5) | 0.4 (0.13) |
Full AGB Range | >100 Mg/ha | ≤100 Mg/ha | |||||||
---|---|---|---|---|---|---|---|---|---|
RMSE | nRMSE | Bias | RMSE | nRMSE | Bias | RMSE | nRMSE | Bias | |
Site | (Mg/ha) | (%) | (Mg/ha) | (Mg/ha) | (%) | (Mg/ha) | (Mg/ha) | (%) | (Mg/ha) |
PALSAR-2 | |||||||||
Lope | 89.23 | 25.24 | −0.53 | 94.84 | 23.77 | −0.69 | 16.40 | 110.84 | 0.69 |
Mondah | 51.23 | 50.44 | −0.17 | 85.45 | 31.52 | −1.82 | 16.03 | 101.71 | 0.66 |
Ogooue | 86.65 | 30.81 | 2.18 | 91.23 | 29.41 | 2.46 | 26.07 | 67.06 | −0.13 |
UAVSAR | |||||||||
Lope | 72.43 | 25.41 | −0.63 | 84.91 | 21.79 | −0.94 | 11.90 | 90.96 | 0.18 |
Mondah | 47.69 | 51.00 | 0.62 | 83.03 | 30.33 | 0.81 | 15.78 | 108.91 | 0.53 |
Ogooue | 78.84 | 32.69 | −0.04 | 88.54 | 29.33 | −0.33 | 22.87 | 80.11 | 0.96 |
Full AGB Range | >100 Mg/ha | ≤100 Mg/ha | ||||||||
---|---|---|---|---|---|---|---|---|---|---|
RMSE | nRMSE | Bias | RMSE | nRMSE | Bias | RMSE | nRMSE | Bias | ||
Site | Coherence | (Mg/ha) | (%) | (Mg/ha) | (Mg/ha) | (%) | (Mg/ha) | (Mg/ha) | (%) | (Mg/ha) |
PALSAR-2 | ||||||||||
Lope | w/o | 99.98 | 26.30 | −1.01 | 98.28 | 24.61 | −5.12 | 127.14 | 428.26 | 74.16 |
w/ | 96.49 | 25.38 | −1.35 | 95.24 | 23.85 | −4.97 | 117.13 | 394.56 | 65.04 | |
Mondah | w/o | 84.66 | 61.70 | −2.93 | 108.79 | 40.05 | −45.95 | 57.11 | 231.06 | 33.05 |
w/ | 72.82 | 53.08 | −2.08 | 95.19 | 35.04 | −30.84 | 46.48 | 188.05 | 21.97 | |
Ogooue | w/o | 99.44 | 34.66 | 2.97 | 94.98 | 30.60 | −7.01 | 137.01 | 298.37 | 105.30 |
w/ | 96.25 | 33.55 | 1.85 | 92.46 | 29.79 | −7.41 | 128.85 | 280.61 | 96.79 | |
UAVSAR | ||||||||||
Lope | w/o | 83.98 | 25.24 | 1.54 | 86.46 | 22.57 | −2.91 | 67.02 | 240.69 | 28.45 |
w/ | 81.87 | 24.61 | 2.91 | 84.00 | 21.93 | −1.45 | 67.59 | 242.76 | 29.30 | |
Mondah | w/o | 80.74 | 64.61 | 1.76 | 104.34 | 38.43 | −42.11 | 59.03 | 254.70 | 32.21 |
w/ | 71.72 | 57.40 | 1.41 | 96.51 | 35.54 | −33.17 | 47.42 | 204.61 | 25.43 | |
Ogooue | w/o | 97.36 | 37.94 | −2.49 | 95.22 | 31.52 | −18.76 | 107.06 | 284.75 | 75.86 |
w/ | 92.00 | 35.85 | −1.84 | 91.16 | 30.17 | −16.21 | 95.93 | 255.14 | 67.30 |
Full AGB Range | ||||
---|---|---|---|---|
Site | # of Scales | RMSE (Mg/ha) | nRMSE (%) | Bias (Mg/ha) |
PALSAR-2 | ||||
Lope | 0 | 104.70 | 27.54 | −2.40 |
1 | 99.20 | 26.09 | −1.84 | |
2 | 97.02 | 25.52 | −1.38 | |
3 | 96.49 | 25.38 | −1.35 | |
Mondah | 0 | 96.91 | 70.64 | −1.15 |
1 | 83.44 | 60.82 | −2.89 | |
2 | 74.68 | 54.43 | −1.75 | |
3 | 72.82 | 53.08 | −2.08 | |
Ogooue | 0 | 116.78 | 40.70 | 0.82 |
1 | 106.57 | 37.15 | 1.84 | |
2 | 98.62 | 34.37 | 2.29 | |
3 | 96.25 | 33.55 | 1.85 | |
UAVSAR | ||||
Lope | 0 | 94.12 | 28.29 | 7.24 |
1 | 84.84 | 25.50 | 4.47 | |
2 | 82.28 | 24.73 | 3.89 | |
3 | 81.87 | 24.61 | 2.91 | |
Mondah | 0 | 89.87 | 71.92 | 0.85 |
1 | 79.53 | 63.65 | 1.99 | |
2 | 73.82 | 59.08 | 1.43 | |
3 | 71.72 | 57.40 | 1.41 | |
Ogooue | 0 | 118.99 | 46.37 | −4.53 |
1 | 103.91 | 40.49 | −1.86 | |
2 | 94.07 | 36.66 | −1.88 | |
3 | 92.00 | 35.85 | −1.84 |
Feature Names | Feature Importance | |||
---|---|---|---|---|
Sensor | Site | Rank | (%) | |
PALSAR-2 | Lope | 1 | HV backscatter (scale 1) | 8.52 |
2 | HH coherence (pixel level) | 5.97 | ||
3 | HV backscatter (pixel level) | 4.72 | ||
Mondah | 1 | HH coherence (scale 3) | 25.18 | |
2 | HH coherence (scale 1) | 6.19 | ||
3 | HV Coherence (scale 3) | 3.93 | ||
Ogooue | 1 | Polarization ratio (scale 3) | 6.20 | |
2 | HH coherence (pixel level) | 4.97 | ||
3 | HV coherence (pixel level) | 4.96 | ||
UAVSAR | Lope | 1 | Polarization ratio (pixel level) | 11.80 |
2 | Polarization ratio (scale 1) | 10.41 | ||
3 | Polarization ratio (scale 1) | 7.34 | ||
Mondah | 1 | Polarization ratio (scale 1) | 15.17 | |
2 | HV coherence (scale 2) | 6.28 | ||
3 | Polarization ratio (scale 1) | 5.00 | ||
Ogooue | 1 | HH coherence (pixel level) | 5.39 | |
2 | Polarization ratio (pixel level) | 5.24 | ||
3 | HV coherence (pixel level) | 4.93 |
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Marshak, C.; Simard, M.; Duncanson, L.; Silva, C.A.; Denbina, M.; Liao, T.-H.; Fatoyinbo, L.; Moussavou, G.; Armston, J. Regional Tropical Aboveground Biomass Mapping with L-Band Repeat-Pass Interferometric Radar, Sparse Lidar, and Multiscale Superpixels. Remote Sens. 2020, 12, 2048. https://doi.org/10.3390/rs12122048
Marshak C, Simard M, Duncanson L, Silva CA, Denbina M, Liao T-H, Fatoyinbo L, Moussavou G, Armston J. Regional Tropical Aboveground Biomass Mapping with L-Band Repeat-Pass Interferometric Radar, Sparse Lidar, and Multiscale Superpixels. Remote Sensing. 2020; 12(12):2048. https://doi.org/10.3390/rs12122048
Chicago/Turabian StyleMarshak, Charlie, Marc Simard, Laura Duncanson, Carlos Alberto Silva, Michael Denbina, Tien-Hao Liao, Lola Fatoyinbo, Ghislain Moussavou, and John Armston. 2020. "Regional Tropical Aboveground Biomass Mapping with L-Band Repeat-Pass Interferometric Radar, Sparse Lidar, and Multiscale Superpixels" Remote Sensing 12, no. 12: 2048. https://doi.org/10.3390/rs12122048