A test of the vertical spatial accuracy was conducted on the njdem100 coverage. At least 4 random points were generated within each 30-minute polygon. Testing was conducted using the ArcView RMSEr.avx extension. The test procedure involved consecutively locating check points on topographic elevation contour lines or benchmark locations located closest to the randomly generated points. Each grid possesses a directory-level computer file structure.
Grids use a hierarchical tile-block structure.
Each grid is first divided into uniform square units called tiles. Each tile represents an actual portion of geographic space. A tile is divided into blocks. A block is made up of square cells arranged in a Cartesian matrix consisting of rows and columns. In addition to these files, each grid includes two associated INFO files residing under the INFO directory within the root workspace.