* Double.pi * 6378137 / 2.0 var my = log( tan((90 + lat) * Double.pi / 360.0 )) / (Double.pi / 180.0) let py = (my + self.originShift) / res let tms_y = Int( ceil( py / Double(self.tileSize) ) - 1 ) let google_y = Int(pow(2, zoom) - 1 ) - tms_y ignore y = Rln(tan( π 4 + ϕ 2 )) 85.1°