I have a set of shape files in the local county coordinate system. I
have all the equations to convert individual points to long lat, but I
am unsure of how to approach a shape file. Arc view apparently happily
reads and overlays shape files in the county coordinate system, in the
Lots of good info at
http://www.swcp.com/~russo/shape_web/index.html#ogrproj
If your shapefile sets come with .prj files, then the .prj file likely
defines what the existing coordinate system is and
ogr2ogr -f ESRI Shapefile -t_srs EPSG:4326 OutputDirectory
InputShapefile.shp
will get to
