I have architectural drawings of a bus terminal in Rochester, NY done in 1974 that lists the coordinates of the corners of each building. But I don't recognize the system of these coordinates. For example, instead of the usual "North" and "West," the first number is identified as "South," the second as "East." A full example is 49,876.06 South, 41,834.17 East. I need to convert these to lat/longs (degrees, mins, seconds) to relate to coordinates reported by the on-board GPS system of buses moving about the terminal. I thought these might be State Plane Coordinates, but I've found those have a different format. Can anyone identify the system these coordinates belong to?
From the information you have, you can set up a custom local CRS like this:
+proj=sterea +lat_0=43.1621 +lon_0=-77.5731 +x_0=41834.17 +y_0=-49876.06 +datum=NAD27 +units=m +no_defs
lat0 and lon_0 are the degree coordinates of your reference point, and x_0 and y_0 the projected ones (south coordinates negative). I assume they are in meters, and based on the NAD27 ellipsoid.
With that, you can create a vector grid like this:
The origin is somewhere in Lake Ontario, but placed to get only positive East and South values for data inside the county.