Environmental Engineering Reference
In-Depth Information
Fig. 6.25
Hydraulic depth of water for a DEM 5 m resolution; b DEM 10 m resolution
Table 6.13 R-square and RMSE between DEM 10 m resolution before and after resampling
with high resolution DEM 5 m
R-square
Mean
Max
RMSE
DEM 10 m before resampling
.894
25.928
322.279
41.284
DEM 10 m after resampling
.995
4.292
155.933
8.966
The production of a large number of elevation error estimates, evenly distributed
over the DEM, makes it possible to explore some general questions such as, how to
identify the statistical characteristics of DEM error, and how much this differs
between the resampled method and the relationship between RMSE of elevation.
The selection of an optimal set of parameters to be used in resampled DEM
required the exploration of different combinations of values. Table 6.13 shows
four statistical analyses for each DEM before and after resampling, comparing it
with high resolution DEM (5 m) as a reference. The statistical analysis is based on
the following parameters:
1. RMSE calculated for selected data points (randomly 10,000 points)
2. Mean error presents the arithmetic mean of the error values and reveals whether
the interpolation has a tendency to under or overestimate on average.
3. Maximum absolute error shows how large the errors can be in extreme cases
Search WWH ::




Custom Search