public float computeScale(){
  double kmPerInch=0.0254e-3;
  double kmPerDeg=Position.EARTH_RADIUS * Math.toRadians(1.0);
  return (float)(dotsPerDeg / dotsPerInch * kmPerInch / kmPerDeg);
}

public float computeScale ( ) { double kmPerInch = 0.0254e-3 ; double kmPerDeg = Position . EARTH_RADIUS * Math . toRadians ( 1.0 ) ; return ( float ) ( dotsPerDeg / dotsPerInch * kmPerInch / kmPerDeg ) ; }
returns the scale . 1 / 100 000 means one cm on the screen corresponds to 1 km in real world .
