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Radiative Transfer Modelling for the Characterisation of Natural Burnt Surfaces
ITT 5526:Algorithm Validation Plan (AVP)
Prof. Philip Lewis1, Dr. Mathias Disney1, Prof. Martin Wooster2, Dr. Bernard Pinty3,
Prof. David Roy4
1. UCL; 2. KCL; 3. JRC; 4. SDSU
Optical fieldwork
Rationale– Generation of 3D RT models
Key structural and radiometric measurements of canopy before/after burn
Spatial distribution of vegetation
– Validation/testing of 3D RT models Characterise before/after signal to simulate
EO signal & compare with EO data
– Site selection encompasses variations of both cover type and fire regimes
Sites: Satara
Models
Sites: Pretoriuskop
Models
Sites: Skukuza
Models
Sites: Mopani
Models
Measurement strategy
Ground-based– 2-3 transects along sites of ~200m per site,
separated by 25m– Hemiphotos, LAI2k every 10-20m, GPS’d and
marked with stakes (to survive burn), spectral measurements and scene components
Helicopter– Follow (as far as possible), same transects but
measure every 50m (ish)– Downward and oblique photography plus spectral
measurements
Measurement strategy
Models •2-3 transects of ~200m per site (avoid edge effects)•Measurements every 10-20m along transects•30-60 points per site
Optical fieldwork: structural
Tree number, location and structure
Tree location (GPS), height (clinometer), DBH (tape),
crown size (tape, clinometer)
Post burn loss of trees?
Crown size
DBH
Optical fieldwork: structural
Pre/post burn oblique aerial photography
Tree height, % tree cover
Optical fieldwork: structural
Gap fraction and LAIeff
Hemiphotos, LAIeff (LAI2000) from same locations within canopy
Optical fieldwork: radiometric (spectral)
Ground-based
•2 x ASD FS Pro spectroradiometer (350-2500nm, 1nm band width) •Following grid pattern laid out for hemiphotos etc.•1-3m above canopy (low stature) - 0.5-1m IFOV (single material)•Above smaller trees (ladder), then….
transects transects
Optical fieldwork: radiometric (spectral)
Helicopter measurements
•ASD mounted on 1.5m pole, extended from helicopter•2nd instrument measuring irradiance on the ground•Multiple measurements at multiple points in each site, from ~100m•I.e. IFOV 20-40m (scene-wide)
Optical fieldwork: radiometric (spectral)
Scene components– Leaf size, shape (photos) and using ASD contact
probe– Burned and unburned material, bark, wood etc.
QuickTime™ and a decompressor
are needed to see this picture.
3D RT models
Models
Structure from 3D modelling software (OnyxTREE) A large range of parameters, existing models, complex/very
flexible Explicit removal of wood, leaf material (post burn)
3D RT models
Wide range of plant shapes and forms including trees, bushes and
grasses
3D RT models
Iterative parameterisation of shape, gap fraction, DBH, height, based on field measurements
– Forward modelling to compare with field measurements– Inverse to derive canopy parameters (fCOVER, LAIeff) from
observations Radiometric (leaf, trunk etc.) info. from ASD measurements
iterate
3D RT models
Spruce plantation….etc.
3D RT models
Model development requires field measurements