Ohio Topographic Map Index
Ohio Geographically Referenced Information Program
Ohio Statewide Imagery Program (OSIP) Downloads - Source for State Color Aerial photography flown in 2007/2008 and LiDAR data flown at the same time.
Images can be viewed with Arc/GIS Explorer (http://www.esri.com/software/explorer/index.html)
Ohio Geodata Distribution (DLGs/DEMs/DOQQs/DRGs)
- Digital Topo Files
DRG - Digital Raster Graphics - i.e. scanned USGS topo sheets projected to Ohio State Plane Coordinates NAD27.
DOQQ - Digital Orthophoto Quad Quads - i.e. BW aerial photography showing one quarter of each quad sheet.
On-Line Calculator for Current Magnetic Declination (http://www.ngdc.noaa.gov/geomagmodels/Declination.jsp)
Lat/Lon to UTM (http://www.ngs.noaa.gov/cgi-bin/utm_getut.prl)
UTM to Lat/Lon (http://www.ngs.noaa.gov/cgi-bin/utm_getgp.prl)
output of either above calculations also shows grid convergence.