Vegetation Classification and Mapping Project Report - the USGS

Overstory and Understory Vegetation Database and Map Products
Upon differential rectification of the scanned raster overlay files, these files are converted to
vector format with the software package R2V by Able Software Company (Cambridge,
Massachusetts) and saved in ArcInfo line format. Vector files from approximately 45
photographs must be edited, edgematched and incorporated into a single ArcInfo coverage to
produce one vegetation map corresponding to the area covered by a single USGS topographic
quadrangle (Figure 10). A typical coverage for the area corresponding to a USGS 1:24,000-scale
map can contain over 4,500 polygons that must be attributed with a dominant vegetation class,
and possibly secondary and tertiary vegetation classes. More than 700 man-hours are required to
produce a single quad-sized vegetation map from the 1:12,000-scale photos, including quality
control checks of labels/line work within and between adjacent maps. Understory maps,
produced from the smaller scale NAPP air photos, require approximately 100 man-hours to
prepare. Although limited funds available for the project precluded a thorough check of
thematic classification accuracy, maps were taken into the field as they were completed to assess
the general agreement between map information and observations on the ground.
Figure 10. Individual vector files from four adjacent photos that have been edited and edge
matched.
Final products included a seamless GIS database in Arc/Info coverage and ArcView shapefile
formats of detailed overstory and understory vegetation communities for the entire park, along
with hardcopy maps plotted at 1:15,000 scale corresponding to the area covered by 25 individual
USGS 7.5-minute topographic quadrangles (Figures 11 and 12). Each map sheet contains a
color-coded legend and brief description of all vegetation classes found in GRSM. A
demonstration of additional digital/hardcopy products that can be created for particular areas of
interest as a result of the vegetation database development include color orthophoto mosaics and
drapes of maps/images on the DEM to enhance visualization of vegetation patterns with respect
22