?' iff ,#V^ ^;A>f ^ ,<M 



2C.O 24 i 



«■» !2i Jo.4 il 



«° M.I J, o 21 



|1 



las ' il» 



Figure 43. Example of a hand-annotated hydrographic map from a Florida project site. The 

 depths have been corrected for tide and are referenced to mlw. (Map courtesy 

 of USAE District, Mobile) 



caused by different drawing styles or methods of smoothing topographic 

 variations. 



In order to be able to manipulate three-dimensional (X, Y, and Z) data, 

 display and plot it at different scales, and compare different data sets, it is 

 necessary to use one of the commercial mapping programs such as Radian 

 Corporation's Contour Plotting System 3 (CPS-3) or Golden Software's 

 Surfer. These are comprehensive packages of file manipulation, mapping 

 algorithms, contouring, and two- and three-dimensional display. Their use 

 requires considerable training, but they are powerful analysis tools. 



The raw data used by mapping programs consist of data in X-Y-Z form. 

 As described in the previous section, if the data are derived from old maps, 

 they must first be corrected to a common datum, map projection, and coor- 

 dinate system. For small files, visual examination of the data may be worth- 

 while in order to inspect for obviously incorrect values. Because it is 

 laborious to review thousands of data points, simple programs can be written 

 to check the raw data. For example, if all the depths in an area are expected 

 to be between +5.0 and -40.0 ft, the program can tag depths that are outside 



110 



Chapter 5 Analysis and Interpretation of Coastal Data 



