Digital Geodata Series
DGS98-4 A 30-Second State Plane Coordinate Grid for New Jersey
A 30-second grid covering New Jersey was generated using the ARC/INFO Geographic
Information System (GIS). The grid was created and built as a tool for
georegistering page size (8.5" x 11") field sheets using a GIS. The grid
was generated as a geographic grid then projected to the 1983 North American
Datum in State Plane Coordinate Feet. The grid was built solely as a line
coverage and updated with line attributes indicating the value of each arc
segment in degrees, minutes, and seconds (for example, 743000 equals 74 degrees,
30 minutes, and 00 seconds). A set of coordinate registration points (tics)
covering New Jersey were generated at each latitudinal and longitudinal
intersection point. Tic locations were compared to corresponding tics from
the NJDEP 7-1/2' grid to check spatial accuracy. The comparison of 138 tic
locations showed no spatial deviation between coverages to the nearest tenth
of a foot.
The 30-second coordinate interval provides a GIS basis for registering
field sheets that use photoimagery near their maximum spatial resolution.
About 64, 30-second tiles cover a quarterquad image (Figure 3). Figures 3,
4, and 5 shows the image resolution of a 30-second tile with respect to an
orthoquarterquad image. Figure 4 shows that a 30-second tile fits on a 8.5"
x 11" page at about the 1:10,000 scale. Figure 5 shows the quarterquad image
near its maximum resolution at the 1:4000 scale (the NJDEP quarterquad images
are reported to have a resolution of 5 feet to a pixel).
Figure 1, 1:2,000,000 scale
display of the 30-second grid
Figure 2. 1:250,000-scale display of the 30-second grid.
Figure 3. 1:80,000-scale display of one NJDEP quarter-quad image with the
30-second grid superimposed.
Figure 4. 1:10,000 scale display of one 30-second tile with a NJDEP
quarter-quad image superimposed.
Figure 5. 1:4,000 scale display of a NJDEP quarter- quad image.