Shoreline t-1 ■ i Shoreline t-2 



South Carolina 



Atlantic Ocean 



Starting Point 

 <r-Y-axis 



Transects (50m spacing) 



Baseline (x-axjs) 



Figure 20. Idealized segment for 

 digitizing shoreline change 

 information 



orthogonally seaward. Thus, in the resulting paired data sets, the x value 

 was the distance from the origin along the baseline, and the y value was the 

 corresponding perpendicular transect distance of the shoreline from the base- 

 line. From 1 to over 25 segments were defined for each base map depending on 

 the length and irregularity of the depicted shoreline. Within any segment, 

 the same number of x-y pairs were digitized for each shoreline. The number of 

 x-y pairs, or transects, depended on segment length. 



63. Start and end points of each segment were punched into the mylar GP 

 grid accompanying each base map to allow easy identification when placed on a 

 light table. The individual survey mylars were overlaid onto this grid sys- 

 tem. Each segment was then digitized with a NUMONICS Model 1224 Digitizer. 

 As the cursor was traced across the shoreline, coordinate pairs were produced 

 and recorded at equal intervals (50 m) along the x-axis from north to south. 

 Each segment was digitized until the entire survey had been completed. The 

 overlying mylar was replaced by the next survey and digitized in the same 



49 



