1. Create a 3-m grid of the bathymetric soundings for the Moriches site using the SwathEd routine weigh_grid.
Command line: weigh_grid -fresh_start -omg -tide -coeffs -mindep -2 -maxdep -800 -beam_mask -beam_weight -custom_weight EM1000_Weights -butter -power 2 -cutoff 6 -lambda 1.5 gridFile filename.merged
2. Create a shaded-relief image of the bathymetry using SwathEd routine addSUN (sun elevation of 45 degrees from 60, vertically exaggerating 4 times). The shaded relief file created from the grid is mapped into the same projection as the grid and carries over the projection information (custom Mercator projection, central meridian -75 degrees, latitude of true scale 40 degrees north) used to create the grid.
Command line: addSUN -elev 45 -azi 60 -vert_exag 4.0 gridFile.r4 filename.shade
3. Use a two-point linear contrast stretch (0-254; 255 is no data) to enhance the shaded-relief image:
Command line: stretchacres -low 150 -high 200 -in filename.shade -out filename_shade.stretch
Note: An error in the UNB processing software that incorrectly projected the multibeam observations onto a plane was discovered in 2003. These data were processed with corrected software.
Command line: rawtopgm -headerskip 1024 image_width image_height filename_shade.stretch | pnmtoTIFF -none - > filename.tif
Command line: jview filename_shade.stretch