modified from: Cross, V.A. and Schwab, W.C., 1998. Digital Sidescan-Sonar Imagery of the
   Manchas Interiores-Manchas Exteriores Coral Reef Complex, Mayagüez, Puerto
   Rico. Open-File Report 98-427

This directory contains files in Arc/INFO format and consists of the complete sidescan sonar mosaic, bathymetric data, 
ship tracklines, Puerto Rico coastline, and sediment sample locations and analysis information. All of the data are mapped
in a Universal Transverse Mercator projection (UTM), zone 19, using the WGS84 reference ellipsoid.


 BATHY
The digitized bathymetry was furnished courtesy of the Puerto Rico Water Resources Division. In this Arc/Info line coverage,
 the bathy-id attribute corresponds to the bathymetric value in meters.

 INTERP
This Arc/INFO polygon coverage represents the general geologic interpretation of the sidescan-sonar imagery.

 SAMPLES
The sediment samples were collected using a Shipek grab sampler. The sediment textural analysis results are included in this Arc/INFO point coverage.

 TRACKS
The tracklines were derived from the sidescan-sonar navigation at 1 minute intervals. The tracks-id of this line coverage corresponds to the
 trackline number assigned during data collection. Included in this directory is a file called allnav.txt which contains the 1-minute
 sidescan-sonar navigation. This file has 3 columns of information: Julian day and time (in GMT); latitude; and longitude. 
The beginning of each trackline is indicated with the line number.

 RAWGRD
This directory contains the grid of the sidescan-sonar imagery that has not undergone any image enhancement.
 This grid was generated using the Arc/INFO gridimage command. The resolution of the grid is 1m/pixel.

 SONARGRD
This directory contains the grid of the sidescan-sonar imagery that has had an image-enhancing stretch applied to the pixel values.
 This grid was generated in the same way as rawgrd. The resolution of the grid is 1m/pixel.

 SIDESCAN
This directory contains 2 'TIFF' images and their associated world file for use in Arc/Info. 
The file 'rawsonar.tif' is the sidescan-sonar mosaic with no image enhancement applied. This file is the image file used to generate rawgrd.
 The other 'TIF' image, 'anasco.tif', is the enhanced image from which sonargrd is derived. 
These 'TFW' files associated with each of these images allows Arc/INFO to geographically register the images. 
The resolution of these images is 1m/pixel.