title: Offset Lat Lon coordinate by some meter in driving direction and to side
body: <p>I would like to offset a coordinate (Lat/Lon) by a small amount of meters ( 1 - 2 meters ) to the back of a driving vehicle and to the right.</p>
  
  <p>It has to be really exact!</p>
  
  <p>I found a function that seems to work, but is not accurate (or wrong?):</p>
  
  <pre><code>double deltaSide = 1.0; // +=offset to the right
  double deltaRear = 1.1; // +=offset in backwards-direction of driving
  
  //transform to offset to North and East
  double deltaSideN = -deltaSide * sin( m_yaw_d ) - deltaRear * cos( m_yaw_d );
  double deltaSideE = deltaSide * cos( m_yaw_d ) - deltaRear * sin( m_yaw_d );
  
  f_lat_d = f_orgLat_d + deltaSideN / (double)EARTH_RADIUS * rad2grad;
  f_lon_d = f_orgLon_d + deltaSideE / (double)EARTH_RADIUS / cos( f_orgLat_d * grad2rad ) * rad2grad;
  </code></pre>
  
  <p>Is there a more accurate function to do so? Or do I just make a major mistake?</p>
  
  <p>Thanks!</p>