Operational techniques for assessing NSR areas using an airborne multispectral imager (CASI)

Airborne multi-spectral (CASI) imagery has been acquired for approximately 80,000 hectares in the Prince George Forestry Region in B.C. This work has included validation test area at the Inga Lake Experimental Test Site and a more operational test at Big Lake in the Dawson Creek District. The valida tion work showed that the CASI can reliably detect individual isolated coni fers down to about 75 cm height provided there are no significant obscuring effects due to deciduous trees or shrubs. The conifers are detected using spectral signatures, Then a "well-spaced" mask is applied to remove stems t hat are too close to other stems. The forest cover polygons are imported di gitally and stem densities are calculated for each polygon and output as at tribute file for each polygon. The stem densities are also calculated local ly using a circular kernel of 0.1 ha size. The resultant stem density maps show the high variability of stem densities within most forest cover polygo ns. Finally, an example of an OAF (Operational Adjustment Factor) calculati on is shown. The OAF image is generated by superimposing a disk of 2.7m dia meter on each identified well-spaced stem and then calculating the residual gaps.