static string GetFilename(double lat, double lng)
{
int x = (lng < 0) ? (int) (lng - 1) : (int) lng; //(int)Math.Floor(lng);
int y = (lat < 0) ? (int) (lat - 1) : (int) lat; //(int)Math.Floor(lat);
int id = y*1000 + x;
if (filenameDictionary.ContainsKey(id))
{
string filename = filenameDictionary[y*1000 + x];
return filename;
}
return "";
}