Integrating Airborne LiDAR and Terrestrial Laser Scanner for Accurate Estimation of Above-ground Biomass/Carbon of Tropical Forests Accuracy Matters Muluken N. Bazezew *, Yousif A. Hussin, E. H. Kloosterman, Ismail M. Hasmadi 3 rd International Convention on Geosciences and Remote Sensing Oct , 2018 Ottawa, Ontario, Canada Dilla University Ethiopia ITC, The Netherlands University Putra Malaysia

OUTLINES ___________________________________________________________________________________________________________________________________________________________ 3 rd International Convention on Geosciences and Remote Sensing  INTRODUCTION  OBJECTIVES  RESEARCH METHODS  RESULTS AND DISCUSSION  CONCLUSION AND RECOMMENDATIONS  ACKNOWLEDGMENTS 2

INTRODUCTION ___________________________________________________________________________________________________________________________________________________________ 3 rd International Convention on Geosciences and Remote Sensing  GHGs emissions; Impact on climate  UNFCCC, Kyoto Protocol (192 countries) 3

3 rd International Convention on Geosciences and Remote Sensing 4 INTRODUCTION ___________________________________________________________________________________________________________________________________________________________

3 rd International Convention on Geosciences and Remote Sensing The growing need of REDD+ MRV!! 5 INTRODUCTION ___________________________________________________________________________________________________________________________________________________________

3 rd International Convention on Geosciences and Remote Sensing To meet the requirements of REDD+ MRV for Accurate Inventory !! 6 INTRODUCTION ___________________________________________________________________________________________________________________________________________________________

3 rd International Convention on Geosciences and Remote Sensing ALS TLS  Integration of ALS and TLS for accurate topical forest monitoring  ALS- Upper canopy trees characterization  TLS- Lower canopy trees characterization 7 INTRODUCTION ___________________________________________________________________________________________________________________________________________________________ To meet the requirements of REDD+ MRV for Accurate Inventory !!

OBJECTIVES ___________________________________________________________________________________________________________________________________________________________ 3 rd International Convention on Geosciences and Remote Sensing The aim of this research is to develop an approach for estimating accurate AGB/Carbon of the tropical rainforests with integrating Airborne LiDAR Scanning (ALS) and Terrestrial Laser Scanning (TLS). Specifically, in the processing-chain: o Assess LiDAR-CHM in tree crown delineation of the tropical forests o Assess the accuracy of forest parameters (DBH, height) measurement with ALS and TLS o Compare the estimated AGB/Carbon between RS (ALS + TLS) and traditional field-based methods 8

STUDY SITE ___________________________________________________________________________________________________________________________________________________________ 3 rd International Convention on Geosciences and Remote Sensing  Located 3º0’0” to 3º2’0” lat. and 101º38’0” to 101º40’0” lon.  Elevation (15 to 233 m a.s.l).  Encompasses 430 plant species, and >60% of its emergent and middle canopy trees, and the rest understory trees and shrubs. 9

METHODS ___________________________________________________________________________________________________________________________________________________________ 3 rd International Convention on Geosciences and Remote Sensing  TLS data acquiring, processing and analyzing  ALS data acquiring, processing and analyzing  Data Integration 10 Various Image processing, and analysis software were used: ERDAS Imagine and ENVI for image processing, LAStool for ALS point cloud data processing, RiSCAN PRO for TLS point cloud data processing, eCognition for ALS-CHM segmentation, ArcGIS, R-studio.

TLS and Dataset Processing ___________________________________________________________________________________________________________________________________________________________ 3 rd International Convention on Geosciences and Remote Sensing RIEGL VZ-400 Terrestrial Laser Scanning sensor features Measurement range m Precision3 mm Accuracy5 mm Beam divergence0.35 mrad Footprint size at 100m30 mm Measurement (pulse) rate kHz Scan angle range (degree)100 o (+60 o / -40 o ) Laser wavelengthNear-infrared (1550 nm) GPS receiver Integrated, L1, with antenna Scanning mechanismRotating multi-facet mirror Scan speed lines/sec Weight9.6 kg Operating temperature0 to +40 o C; standard operation HumidityMax. 80%, non-condensing at +30 o C 11

3 rd International Convention on Geosciences and Remote Sensing 12 TLS and Dataset Processing ___________________________________________________________________________________________________________________________________________________________

3 rd International Convention on Geosciences and Remote Sensing 13 TLS and Dataset Processing ___________________________________________________________________________________________________________________________________________________________ Measuring with RiSCAN PRO

ALS and Dataset Processing ___________________________________________________________________________________________________________________________________________________________ 3 rd International Convention on Geosciences and Remote Sensing Sensor FeatureDescription Pulse rate Range between 70 kHz and 240 kHz Scan angle60° Scan patternRegular Beam divergence0.5 mrad Line/secMax. 160 A/c ground speed90 kts Target reflectivity % (vegetation 30%, cliff 60%) Flying height m Laser points/m 2 5 to 6 points with 808 m to 1155 m swath width Spot diameter (laser) m Max (above ground level)

3 rd International Convention on Geosciences and Remote Sensing 15 ALS and Dataset Processing ___________________________________________________________________________________________________________________________________________________________

3 rd International Convention on Geosciences and Remote Sensing ALS-TLS Integration ___________________________________________________________________________________________________________________________________________________________ 16

RESULTS ___________________________________________________________________________________________________________________________________________________________ 3 rd International Convention on Geosciences and Remote Sensing TLS-based DBH Accuracy Tree parameter No. of ObservationsR2R2 r RMSE Bias (cm) (cm)(%) DBH –

3 rd International Convention on Geosciences and Remote Sensing Reference polygons 1:1 matched polygons Over- segmentation Under- segmentationGoodness of fit (D) Accuracy (%) Segmentation Accuracy and canopy cross-sectioning RESULTS ___________________________________________________________________________________________________________________________________________________________

3 rd International Convention on Geosciences and Remote Sensing The average success rate of treetops detection by LiDAR Success rate displays the number of trees (%) that their treetops identified from ALS or TLS. 19 RESULTS __________________________________________________________________________________________________________________________________________________________  Overall- ALS treetop detection potential is 57% of field identified trees, while TLS is 37%.

3 rd International Convention on Geosciences and Remote Sensing LiDAR (ALS and TLS)-based trees height accuracy Tree ParameterNo. of ObservationsR2R2 r RMSE Bias (m) (m)(%) Upper canopy trees height – 1.20 Lower canopy trees height RESULTS ___________________________________________________________________________________________________________________________________________________________

3 rd International Convention on Geosciences and Remote Sensing LiDAR- Vs Field-based AGB/C Method No. of sampled plotsrInterceptSlopeP valueRMSERMSE (%) TLS < ALS < TLS-ALS Integration < RESULTS ___________________________________________________________________________________________________________________________________________________________

3 rd International Convention on Geosciences and Remote Sensing  There was a significant difference between field and various RS techniques-based AGB.  Traditional field-based methods underestimated the AGB.  Complementary use of TLS with ALS improved the accuracy of estimating AGB/C.  If the goal is to get highly accurate AGB/C, integration of TLS and ALS should be chosen.  If the simple parsimonious model is desired, then ALS-based AGB model could be chosen. Method No. of sampled plotsrInterceptSlopeP valueRMSERMSE (%) TLS < ALS < TLS-ALS Integration < RESULTS ___________________________________________________________________________________________________________________________________________________________

3 rd International Convention on Geosciences and Remote Sensing Statistics RS-based AGB (Mg) Field-based AGB (Mg) Combination of upper and lower canopies AGB (Mg) Upper canopy trees (ALS) Lower canopy trees (TLS) Upper canopy trees Lower canopy trees RS (ALS + TLS) methods Field- methods Mean/Plot Std. Dev Min Max Sum  Of a total AGB calculated from RS, 92% is the upper canopy trees AGB, and 8% is lower canopy trees AGB (168.8 Mg.ha -1, 14.2 Mg.ha -1, respectively).  It implies that it was able to capture an average of 14.2 Mg.ha -1 (0.71 Mg.plot -1 ) with the compliment of TLS.  Field methods underestimated AGB by Mg.ha -1, accordingly for about 10.70%. 23 RESULTS ___________________________________________________________________________________________________________________________________________________________

CONCLUSION AND RECOMMENDATIONS ___________________________________________________________________________________________________________________________________________________________ 3 rd International Convention on Geosciences and Remote Sensing  Using ALS for detecting single tree in the complex biophysical structure of tropical rainforest have a potential to recognize not more than two-thirds of the trees.  The dense canopy and interlocking crown structure of the tropical forest results in a low accuracy of crown segments.  The TLS-based DBH measurements method used in this paper through distance function algorithm in the RiSCAN PRO offers more accurate result than the automatic detection of trees and determination of DBH.  Results from model evaluations based on ALS and TLS dataset proof that this approach can enhance the accuracy of predicted AGB or carbon stock than traditional field-based.  Integration enables to detect a comparable number of trees identified in the field. 24

3 rd International Convention on Geosciences and Remote Sensing Main sources of errors  Field-based tree height measurements (with Leica laser DISTO D510)  Hunter et al. (2013) have reported that height error ranging from 3–20% of the total height results contribute to 5–6% of uncertainty in estimated biomass. 25 CONCLUSION AND RECOMMENDATIONS ___________________________________________________________________________________________________________________________________________________________

3 rd International Convention on Geosciences and Remote Sensing  Although the number of plots acquired in this study was small, the range of canopy structures and the approach used for individual tree parameters measurement provide a clear indication of the potential of integrating ALS and TLS system.  However, the TLS data acquisition through observations of plots from multiple scanning viewpoints to reduce the occlusion effect requires more investigation.  The proposed approach can also be used to accurately predict forest structural variables other than AGB, such as stand density, basal area, and stand volume. 26 CONCLUSION AND RECOMMENDATIONS ___________________________________________________________________________________________________________________________________________________________

ACKNOWLEDGMENT ___________________________________________________________________________________________________________________________________________________________ 27 Organizers of 3 rd International Convention on Geosciences and Remote Sensing

3 rd International Convention on Geosciences and Remote Sensing Oct , 2018 Ottawa, Ontario, Canada Dilla University Ethiopia ITC, Netherlands University Putra Malaysia THE END THANK YOU FOR LISTENING!! Integrating ALS and TLS for Accurate Tropical Forest Monitoring 28

Corresponding Author Address: Muluken N. Bazezew Dilla University College of Agriculture and Natural Resources P.O. Box: 419 Dilla, Ethiopia 29