The first step was to produce a 1200 x 1800 grid, georeferenced at
MD State Plane 1983, NAD 83 with units in meters, that would encompass
the entire State of Maryland. A retangular vector was created starting
at the point of origin (northing 0.0 and easting 0.0) and extending to a
point in space that falls beyond the extents of the MD County Boundary.
The outer extents were also coordinated in multiples even to the 1200 x
1800 meter grid to make processing of the grid consistent to that of the
retangular vector. Within TNT mips, the vector grid analysis process was
used to process the grid itself. The retangular area vector was used as
the input object and width & length was set to 1200 x 1800 meters. A
symbolic grid system and a combined symbolic system was selected to
create the polygon attribute fields. The x and y place of origin was set
to the same point of origin as the vector area input object. The snap
mode was set to "Both to Vertex". The process was then applied and the
data was saved as a new vector object.
ESRI software was used to add attributes based on the 3600 square
meter grid. Each grid cell in this data was attributed to the 3600 meter
grid cell that fell within, and the appropriate sub-tile number
(1through 6) was added to each 1200 x 1800 meter cell.