I want to define a custom crs valid for Mexico. The context is that older cartography in Mexico is based on the NAD27 datum. I wanted to test the following proj4 string
+proj=longlat +ellps=clrk66 +towgs84=-12,130,190,0,0,0,0 +no_defs
Nevertheless , when I test my string with 19N 99W (19,-99) I get the following values
testing the proj 4 definition included in Qgis gives the same results.
These are wrong since the resulting north should be around 19 and the resulting east around -99. I wonder if anyone can tell me what I am doing wrong. Thanks in advance