7th Workshop on Forest Fire Management - EARSeL, European ...

Correction of topographic effects influencing the differenced normalized burn ratio’s optimality for estimating fire severity 275
Figure 3 - Mean topographically uncorrected, c-corrected and modified c-correction dNBR optimality
score by aspect class (a), average illumination class (b).
In comparison with topographically uncorrected data, both topographic
correction techniques increased the optimality of badly illuminated areas
but the modified c-correction method ameliorated more than the original
c-correction technique. For well illuminated areas, however, dNBR optimality
dropped after c-correction while the modified c-correction realized
slightly better optimality scores than uncorrected data (see figure 3).
4 - Conclusions
Based on the spectral index theory, the effect of illumination on the dNBR
optimality for assessing fire severity using pre- (2006) and post-fire (2007)
Landsat TM imagery was evaluated for the 2007 Peloponnese wildfires. To
improve the performance of the index, the c-correction method and a modified
version of this technique were applied to derive terrain corrected
reflectance. The resulting mean dNBR optimality scores of topographically
uncorrected, c-corrected and modified c-correction data were respectively
0.57, 0.59 and 0.66. The modified c-correction method resulted in a more