dem users manual - asprs

hydrographic data. Tables 1 through 4 provide sample dataset calculations of FVA, CVA, SVA and other accuracy
reporting statistics from the quantitative assessment of a lidar dataset.
Table 1 ― DTM Acceptance Criteria from Sample Project Quality Plan
Table 2 ― FVA, CVA and SVA at 95% Confidence Level
Table 3 ― 5% CVA Outliers Larger than 95 th Percentile
Table 4 ― Descriptive Statistics by Land Cover Category
Figure 9 shows errors detected from Dewberry’s independent QA/QC assessments of elevation datasets. Figure
9a illustrates a scan line with high elevations, merged with adjacent scan lines which had the correct elevations; this
tile also was initially classified as bare-earth terrain but it is clear that vegetation still exists within this tile. Figure
9b illustrates a processing error by the vendor where an antenna offset was not applied when reducing the data.
Figures 9c, 9d and 9e show the results of over-smoothing. Figure 9c shows correct processing in the north
(Area A), over-smoothing in the south (Area B). Figure 9d uses cross sections that show a stream in the north and a
pseudo-levee in the south. Figure 9e is an orthophoto that shows the DTM should depict a stream throughout.
MAPPS/ASPRS 2006 Fall Conference
November 6 – 10, 2006 * San Antonio, Texas