| Q: Is there an alternative way to specify the location other than using lat/lons? |
Ans: Yes, you can specify the location in terms of XY-coordinates. To do this you must set the top_lat, top_lon to zero, bot_lat to the width of the image, and bot_lon to the height of the image, and then you can represent the latitudes and longitudes of the nodes in terms of XY-coordinates, with the top left-hand corner being (0,0). The latitudes map to the X values and the longitudes map to the Y values.