I need to determine a person's location within 50m. I'm wondering if I should use navigator.location.watchPostion() or call getCurrentPostion() over and over again. watchPostion() is the proper W3C API for doing what I want, but practically, it seems to be overkill.

Here's my code:

var map = null;

var marker = null;

var layer = null;



function locFn(pos) {



  var lat = pos.coords.latitude;

  var lon = pos.coords.longitude;



  $(#hlat).val(lat);

  $(#hlong).val(lon);



  document.getElementById(lnkMap).href = 

    http://maps.google.com/maps?q=My+Loc@ + lat

    + , + lon + &z=18&t=h;



  var point = new GLatLng(lat, lon);



  if (pos.coords.accuracy < 100) {

    map.setCenter(point, 18);



    if (marker != null) {

      marker.setLatLng(point);

    }

    else {

      var ico = new GIcon();

      ico.image = img/Blue-Dot.png;

      ico.iconSize = new GSize(22, 22);

      ico.iconAnchor = new GPoint(11, 11);

      marker = new GMarker(point, { icon: ico });

      layer = map.addOverlay(marker, { title: You are here. });

    }

  }

  else if (pos.coords.accuracy > 2000) {

    if (marker != null) { marker.setLatLng(point); }

    map.setCenter(point, 15);

  }

  else if (pos.coords.accuracy > 900) {

    if (marker != null) { marker.setLatLng(point); }

    map.setCenter(point, 16);

  }

  else if (pos.coords.accuracy > 100) {

    if (marker != null) { marker.setLatLng(point); }

    map.setCenter(point, 17);

  }

}



function locFail() {

  //alert(Failed to retrieve location.);

}



var watchID = null;



function processPoints() {

  map = new GMap2(document.getElementById(map_canvas), 

                  { mapTypes: [G_HYBRID_MAP] });

  try {

    watchID = navigator.geolocation.watchPosition(locFn, locFail,

          { enableHighAccuracy: true });

  }

  catch(err) { /* desktop?*/ }

}

$(function(){processPoints();});

I've noticed watchPostion() seems to ultimately result in more accuracy (after a while), but I'm wondering if the position changes so fast that it results in a lot of thing being downloaded to my map canvas, with constant http requests that are soon out-of-date, replaced by the new ones coming in. When I use watchPosition(), it does take a while before the page loads.