High Spatial Resolution Digital Imagery
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tion classes were aggregated from the complete set of 18 classes. The objective
of this product is to provide the District, Field Office, and spray contractors with
the optimal level of vegetative information needed to direct herbicide application
methods. This two layer map would be stored in a digital format and provide
valuable spatial information for seasonal (or long-term) monitoring of hyacinth
and lettuce growth and movement within the Lake. The map could also be plotted
to a large map sheet and provided directly to spray crews with the intent of in-
creasing the efficacy of herbicide application.
7.7
Results for Wetland Vegetation Mapping Over Blackwater Wildlife
Refuge
The results of the SAM classification and the maximum likelihood classifi-
cation were combined to create the complete vegetation class maps. An evalua-
tion of the 37 classes associated with the southern mosaic indicated significant
confusion within and between the vegetation types, particularly within the marsh
communities. Therefore, a number of classes were combined, based on the spec-
tral and spatial characteristics of the class signatures in the completed thematic
map. A simple GIS operation was used to recode (or renumber) classes that were
spectrally similar. The resulting vegetation map depicted 26 vegetation classes.
The northern mosaic maintained 19 vegetation classes. Figure 46 shows the 30
June (southern mosaic) class map after application of the minimum mapping unit
filter. Figure 47 shows the 7 June (northern mosaic) class map after filtering and
subsetting with a 500-m buffer around the Refuge boundary.
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