MIL-PRF-32030

Abstract

This specification defines the content and format for the U.S. Naval Oceanographic Office NAVOCEANO Digital Bathymetric Data Base - Variable Resolution (DDBDB-V) product. DBDB-V is a digital bathymetric data base that provides ocean depths at various gridded resolutions. <b><u>Intended Use:</u></b> DBDB-V is a digital bathymetric data base that provides ocean depths at various gridded resolutions. DBDB-V was developed by NAVOCEANO to support the next generation of bathymetric chart products, and to provide bathymetric data to be integrated with other geophysical and environmental parameters for ocean modeling. DBDB-V is a combination of different resolution gridded bathymetric data bases. The depth posts, or grid nodes, are defined by the intersections of rows and columns within a matrix. The matrix intervals, or grid post spacing, defined in terms of geographic arc minutes will be 0.5, 1, 2 and 5 minutes for Version 1.0 of DBDB-V. DBDB-V is developed by the Naval Oceanographic Office and combines in one data base structure different resolutions of gridded bathymetric data bases. The coarser resolution data grids (1, 2 and 5 arc minute grids) are constructed by digitizing bathymetric contours of hard copy charts. The digitization rate and nominal chart scales are 21 measurements per inch of contour at a nominal chart scale of 1:1000000 for the 1 minute grid, 21 measurements per inch of contour at a nominal chart scale of 1:1000000 for the 2 minute grid, and 10 measurements per inch of contour at a nominal chart scale of 1:4000000 for the 5 minute grid. These digitally rendered contours are then put through a gridding routine developed by the Naval Oceanographic Office. This routine takes the values that fall within a grid node area of influence and utilizing a multi-stage minimum-curvature spline algorithm, interpolates the values to derive a single representative depth value for each grid node (1, 2 or 5 arc minute grid node spacing). The finer resolution data grid (0.5 arc minute grid) is generated in two distinct manners: a. Hard copy charts have contour digitization performed at a rate of 21 measurements per inch of contour and at a nominal chart scale of 1:500000. The digitized contours and/or digital source data are input to a gridding routine developed by the Naval Oceanographic Office. This routine takes the values that fall within a grid node area of influence and, utilizing a multi-stage minimum-curvature spline algorithm, interpolates the values to derive a single representative depth value for each grid node (0.5 arc minute spacing), or b. It can be derived directly from higher resolution bathymetric data grids by application of computer algorithms. Upon completion of the bathymetric grid it is matched to the World Vector Shoreline, or higher resolution shorelines, and discrepancies are resolved. A land mask is constructed, for that portion of the grid over land, filled with null values. <br>