Process Description:
Contact lines for the surfical sediment thicker than 50 ft. overlying Coastal Plain units for the saqfr250 coverage were digitized using ARC/INFO Geographic Information Systems (GIS) software and CalComp 9100 and 9500 digitizers with reported accuracy's of +/- 0.005 in. (+/-0.127 mm). Coverage features were digitized directly into NAD27 state-plane-coordinate (SPC) feet using registration points (tics) corresponding to the corners of U.S. Geological Survey 7-1/2 minute quadrangles. Tic locations were taken from the N.J. Dept. of Environmental Protection coverage /data/mapgrids/spctiles. All maps were georegistered using a maximum root-mean-square (RMS) error of .006 (about 12 ft. at the 1:24,000 scale or 100 ft. at the 1:100,000 scale) using a set of at least four tics. Proof plots were made for each map and compared to the originals. Any line that deviated from the original position by more than .012" (about 1 to 1.5 line widths) were re-digitized until acceptable results were obtained. The coverages were projected into NAD83 SPC feet after final map editing. Geologic-unit contacts for the glacial parts of the saqfr250 coverage were compiled by scanning mylar separates of the U.S. Geological Survey central bedrock sheet and the N.J. Geological Survey Open-File Map OFM-3 using a CalComp ScanPlus II scanner set at 400 dpi resolution. The scanner accuracy is +/-.25%. The images were saved using a TIFF 5.0 image format. The images were center-line traced into a vector format using CADCore Version 2.0 raster-to-vector conversion software. The vector lines were saved as ARC/INFO generate files with a line format. These line coverages were then generated and edited as ARC/INFO GIS polygon coverages in board inches. Proof plots were made of each coverage on mylar and compared to the original base maps. Any line that deviated from the original position by more than .012 in. (about 1 to 1.5 line widths) were re-digitized, re-plotted, and corrected until the desired results were obtained. CalComp 9100 and 9500 digitizers were used for editing. The coverages were then transformed into NAD27 SPC feet using corner points of 7-1/2 minute quadrangles for the transformation links. RMS registration errors from the transformation process were less than .006. Coverages were projected into NAD83 SPC feet after final map editing. The glacial parts of the saqfr250 coverage stem from clipping polygons in the /geodata/geology/srficial/state/glacial/sediment coverage with the set of 50 ft. isopach lines from the /geodata/geology/srficial/state/glacial/thickness coverage. Geonum item values for each polygon were used for combining lithologic units into aquifer units using the ARC/INFO dissolve function. Any resulting polygons less than 1,000,000 square feet in area were then selected and deleted. Polygon labels for the saqfr250 coverage were then added and updated.