Remote Sensing · Change Detection

Post-Fire Vegetation Damage Assessment

Pre/post-fire change detection of the January 2025 Pacific Palisades Fire using Wyvern Dragonette hyperspectral imagery and red-edge vegetation indices, mapping where vegetation was lost across a wildland–urban interface in Los Angeles County.

ERDAS IMAGINEHyperspectral VNIR Red-edge indicesChange detectionArcGIS Pro
ChangeCIred-edge change detection over the burn area
ΔCIred-edge — red marks significant chlorophyll/vegetation loss, yellow marks increase
01The problem

The Palisades Fire struck a coastal chaparral wildland–urban interface with steep terrain, damaging vegetation and infrastructure across Los Angeles County.

Fast, reliable maps of where vegetation was lost and how severe the burn was support burn-severity assessment, recovery monitoring, and future fire-risk planning.

Index-based change detection turns two satellite images into a clear, quantitative map of vegetation damage.

Study area in Los Angeles County
Study area — Pacific Palisades / Santa Monica Mountains, LA County
02Data

Commercial VNIR hyperspectral imagery from the Wyvern Dragonette-001 satellite, chosen for its narrow red-edge bands that are highly sensitive to vegetation stress.

  • Resolution: 5.3 m, 23 bands (500–800 nm), 12-bit
  • Pre-fire: 04 Nov 2024 · Post-fire: 23 Jan 2025
  • Bands used: red-edge (b20, ~750 nm) and NIR (b23, ~799 nm)
Multipoint geometric correction, total RMS 0.0002
Multipoint geometric correction — total control-point RMS 0.0002
03Method
  1. Visual co-registration check and multipoint geometric correction (total RMS 0.0002).
  2. Select red-edge (b20) and NIR (b23) bands from the hyperspectral cube.
  3. Convert radiance to TOA reflectance using image metadata.
  4. Stack bands and re-project WGS84 → WGS 1984 UTM Zone 11N.
  5. Compute CIred-edge and NDVIred-edge for both dates.
  6. Difference (post − pre) to build change maps; negative Δ = vegetation loss.
04Results
−0.30Mean ΔCIred-edge (chlorophyll decline)
−0.07Mean ΔNDVIred-edge (greenness decline)
0.0002Geometric correction RMS error

Vegetation loss concentrated in forested hilltops with high burn severity, while urban and built-up areas showed little change. Both indices agreed spatially: CIred-edge captured chlorophyll loss and NDVIred-edge captured structural canopy loss, confirming the pattern.

CIRED-EDGE · PRE VS POST

CIred-edge pre-fire
Pre-fire — Nov 2024
CIred-edge post-fire
Post-fire — Jan 2025

NDVIRED-EDGE · PRE VS POST

NDVIred-edge pre-fire
Pre-fire — Nov 2024
NDVIred-edge post-fire
Post-fire — Jan 2025
05Limitations & next steps
  • Calibrate severity thresholds against field or dNBR reference data.
  • Add atmospheric correction (surface reflectance) for cross-sensor robustness.
  • Validate against an independent burn-perimeter dataset.

See the full write-up

Complete README, all maps, and methodology on GitHub.