| This data set is one component of a digital terrain model (DTM) for the Southwest
Florida Water Management District’s FY2006 Digital Orthophoto (B089) and LiDAR Project
(L470/L471), encompassing approximately 1,216 square miles across Citrus and Sumter
counties. The 2006 LiDAR dataset is comprised of 3-D masspoints delivered in the LAS
file format based on the District’s 5,000’ by 5,000’ grid (1,356 cells). The other
DTM component is 2-D and 3-D breakline features in the ESRI ArcGIS Personal Geodatabase
format. In accordance with the 2006 SWFWMD Topographic Database Design, the following
breakline features are contained within the database: closed water bodies (lakes,
reservoirs, etc) as 3-D polygons; linear hydrographic features (streams, canals, swales,
embankments, etc) as 3-D breaklines; coastal shorelines as 3-D linear features; edge
of pavement road features as 3-D breakines; soft features (ridges, valleys, etc.)
as 3-D breaklines; obscured vegetation polygons as 2-D polygons; overpasses and bridges
as 3-D breaklines; 1-foot contours for visualization purposes; and island features
as 3-D polygons. This data falls in Citrus and Sumter Counties. Intensity values,
or the measure of reflectance of the laser are also captured. Breakline features were
captured to develop a hydrologically correct DTM. Contours (1-foot) were generated
from the DTM that meet the National Map Accuracy Standards for 2-foot contours (FEMA
specifications). Bare earth LiDAR masspoint data display a vertical accuracy of at
least 0.3-feet root mean square error (RMSE) in open unobscured areas
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