Converting Longitude & Latitude to X Y on a map with Calibration points

Question

If i have a jpeg map with size sizeX, sizeY

and some calibration points on the map (X, Y, Lon, Lat)

What would be the algorithm for calculating the correspon

Answer 1

If using the Equidistant Cylindrical Projection type map, here is what you need to do:

1. Find the Latitude and longitude of your location tutorial here:
   http://lifehacker.com/267361/how-to-find-latitude-and-longitude
2. Input that information into the following formulas:
   x = (total width of image in px) * (180 + latitude) / 360
   y = (total height of image in px) * (90 - longitude) / 180
   
   note: when using negative longitude of latitude make sure to add or subtract the negative number i.e. +(-92) or -(-35) which would actually be -92 and +35
   
   
3. You now have your X and Y to plot on your image
   
   More information can be found about this formula and the map type here:
   http://www.progonos.com/furuti/MapProj/Dither/CartHow/HowER_W12/howER_W12.html#DeductionEquirectangular