Comparison of LiDAR and Digital Aerial Photogrammetry for Characterizing Canopy Openings in the Boreal Forest of Northern Alberta
Abstract
:1. Introduction
Motivation and Objectives
2. Materials and Methods
2.1. Study Area
2.2. Remote Sensing Data Collection and Pre-Processing
2.2.1. Remote Sensing Data Collection
2.2.2. LiDAR-Based CHM
2.2.3. DAP-Based CHM
2.2.4. Hybrid CHM
2.3. Delineating Canopy Openings
2.4. Validating Canopy Openings—Point-Based Analysis
- Opening class 0: No opening (sky above 1.3 m obscured by vegetation)
- Opening class 1: > 0 to 4 m2
- Opening class 2: > 4 to 20 m2
- Opening class 3: > 20 to 200 m2
- Opening class 4: > 200 m2.
- Identify and isolate points that do not have a neighboring point within a 20 m distance.
- Randomly select one point from the remaining points. Identify all remaining points within a 20 m distance of this point and remove them from the list.
- From the remaining points in the list, select another random point. Identify all the points within a 20 m distance of this point and remove them from the list.
- Repeat step 3 until the list is empty.
- Add the randomly selected samples (steps 2–4) and the isolated samples (step 1) together to obtain a complete set of spatially uncorrelated samples.
2.5. Examination of Opening Characteristics—Area-Based Analysis
2.6. Examination of the Value of DAP in Measuring Height
3. Results
3.1. Opening Maps
3.2. Point-Based Analysis
3.3. Area-Based Analysis
3.4. Value of the Hybrid Model—CHMHybrid vs. CHMDAP Relative to CHMLiDAR
4. Discussion
5. Conclusions
Supplementary Materials
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Publication | Location | Forest Type | Forest Attribute | Investigated Canopy Openings? |
---|---|---|---|---|
Swinfield et al., 2019 [43] | Sumatra, Indonesia | Lowland tropical forest | Tree height, biomass, carbon density | No |
Vastaranta et al., 2018 [44] | Finland | Boreal forest | Forest height, tree density, tree height | No |
Cao et al., 2019 [45] | Eastern China | Subtropical planted forest | Diameter at breast height, Lorey’s height, basal area, stem density, biomass, volume | No |
Filippelli et al., 2019 [37] | Colorado, USA | Montane coniferous | Biomass, basal area, bulk density, Lorey’s height, maximum height | No |
Graham et al., 2019 [46] | British Columbia, Canada | Interior cedar hemlock | Terrain | No |
Iqbal et al., 2019 [47] | Tasmania | Pine plantation | Basal area, stocking, stem volume | No |
Swetnam et al., 2018 [48] | Arizona, USA | Chihuahuan desert scrub, and semi-arid desert grassland | Terrain, vegetation height | No |
White et al., 2018 [8] | British Columbia, Canada | Coastal temperate rainforest | Canopy gaps | YES |
Pearse et al., 2018 [49] | New Zealand | Pine plantation | Stand height, density, basal area, volume | No |
Fankhauser et al., 2018 [50] | Various US states | Various | Tree counts, tree height | No |
Wallace et al., 2016 [42] | Tasmania, Australia | Eucalypt forest | Terrain, canopy cover, vertical canopy profile, stem location, tree height | No |
St-Onge et al., 2015 [51] | Quebec, Canada | Boreal forest | Tree crowns, species, height | No |
White et al., 2015 [52] | British Columbia, Canada | Coastal temperate rainforest | Tree height, basal area, volume | No |
Ni et al., 2014 [53] | Main, USA | Northern hardwood | Canopy height | |
Rahlf et al., 2014 [54] | Southern Norway | Boreal forest | Timber volume | No |
Vastaranta et al., 2013 [55] | Finland | Boreal forest | Tree volume, diameter, basal area, biomass | No |
Gil et al., 2013 [56] | Canary Islands, Spain | Tropical pine forest | Terrain | No |
Bohlin et al., 2012 [57] | Sweden | Boreal forest | Tree height, stem volume, basal area | No |
Järnstedt et al., 2012 [58] | Finland | Boreal forest | Mean tree height, dominant tree height, basal area, volume | No |
St-Onge et al., 2008 [36] | New Brunswick and Quebec, Canada | Balsam fir forest, Boreal forest | Canopy height | No |
Number of Samples | ||
---|---|---|
Opening Class | Disturbed | Undisturbed |
0 | 100 | 300 |
1 | 116 | 102 |
2 | 36 | 30 |
3 | 69 | 104 |
4 | 396 | 582 |
Total | 717 | 1118 |
Class 0 | Class 1 | Class 2 | Class 3 | Class 4 | Total | |
---|---|---|---|---|---|---|
Mean Number of Samples | 207 | 32 | 19 | 25 | 73 | 358 |
Standard Deviation | 3.86 | 3.68 | 2.75 | 3.38 | 4.07 | 4.81 |
Method | Overall Accuracy * (%) | Opening | No-Opening | Kappa | ||
---|---|---|---|---|---|---|
Omission Error (%) | Commission Error (%) | Omission Error (%) | Commission Error (%) | |||
LiDAR | 94.4 | 12.3 | 0.5 | 0.3 | 8.6 | 0.88 |
DAP | 77.4 | 53.7 | 0.1 | 0.0 | 28.1 | 0.50 |
Hybrid | 77.8 | 52.6 | 0.1 | 0.0 | 27.7 | 0.51 |
Opening Class | 0–4 m2 | 4–20 m2 | 20–200 m2 | >200 m2 | |||||
---|---|---|---|---|---|---|---|---|---|
% Area Covered | DAP | Hybrid | DAP | Hybrid | DAP | Hybrid | DAP | Hybrid | |
Undetected | 96.4 | 97.3 | 44.5 | 43.7 | 7.7 | 8.4 | 0.0 | 0.0 | |
<20% | 1.8 | 1.8 | 35.4 | 33.7 | 24.7 | 19.7 | 0.0 | 0.0 | |
20–40% | 0.7 | 0.5 | 13.4 | 15.0 | 40.0 | 38.0 | 10.2 | 6.1 | |
40–60% | 0.3 | 0.2 | 5.6 | 6.3 | 21.6 | 25.6 | 34.7 | 26.5 | |
60–80% | 0.2 | 0.1 | 1.0 | 1.1 | 5.8 | 7.7 | 51.0 | 59.2 | |
80–100% | 0.6 | 0.2 | 0.2 | 0.3 | 0.3 | 0.6 | 4.1 | 8.2 |
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Dietmaier, A.; McDermid, G.J.; Rahman, M.M.; Linke, J.; Ludwig, R. Comparison of LiDAR and Digital Aerial Photogrammetry for Characterizing Canopy Openings in the Boreal Forest of Northern Alberta. Remote Sens. 2019, 11, 1919. https://doi.org/10.3390/rs11161919
Dietmaier A, McDermid GJ, Rahman MM, Linke J, Ludwig R. Comparison of LiDAR and Digital Aerial Photogrammetry for Characterizing Canopy Openings in the Boreal Forest of Northern Alberta. Remote Sensing. 2019; 11(16):1919. https://doi.org/10.3390/rs11161919
Chicago/Turabian StyleDietmaier, Annette, Gregory J. McDermid, Mir Mustafizur Rahman, Julia Linke, and Ralf Ludwig. 2019. "Comparison of LiDAR and Digital Aerial Photogrammetry for Characterizing Canopy Openings in the Boreal Forest of Northern Alberta" Remote Sensing 11, no. 16: 1919. https://doi.org/10.3390/rs11161919