Google Earth API Samples - Hit-Testing (X/Y to Lat/Lon)

Relevant Resources:

• GEView Reference
• google.earth Namespace Reference
• KmlEvent Reference

Relevant Code Excerpt:

var globePlacemark = null;
var terrainPlacemark = null;
var buildingsPlacemark = null;

ge.getLayerRoot().enableLayerById(ge.LAYER_TERRAIN, true);
ge.getLayerRoot().enableLayerById(ge.LAYER_BUILDINGS, true);

google.earth.addEventListener(ge.getGlobe(), 'click', function(evt) {
  if (evt.getButton() != 0)
    return;
  
  // remove old placemarks
  if (globePlacemark)
    ge.getFeatures().removeChild(globePlacemark);  
  if (terrainPlacemark)
    ge.getFeatures().removeChild(terrainPlacemark);
  if (buildingsPlacemark)
    ge.getFeatures().removeChild(buildingsPlacemark);
  
  // hit test and create new placemarks
  var hitTestResult = ge.getView().hitTest(evt.getClientX(), ge.UNITS_PIXELS, evt.getClientY(), ge.UNITS_PIXELS, ge.HIT_TEST_GLOBE);
  if (hitTestResult) {
    globePlacemark = makePlacemark(hitTestResult.getLatitude(), hitTestResult.getLongitude(),
        hitTestResult.getAltitude(), ge.ALTITUDE_ABSOLUTE, 'G');
    ge.getFeatures().appendChild(globePlacemark);
  }
  
  hitTestResult = ge.getView().hitTest(evt.getClientX(), ge.UNITS_PIXELS, evt.getClientY(), ge.UNITS_PIXELS, ge.HIT_TEST_TERRAIN);
  if (hitTestResult) {
    terrainPlacemark = makePlacemark(hitTestResult.getLatitude(), hitTestResult.getLongitude(),
        hitTestResult.getAltitude(), ge.ALTITUDE_ABSOLUTE, 'T');
    ge.getFeatures().appendChild(terrainPlacemark);
  }
  
  hitTestResult = ge.getView().hitTest(evt.getClientX(), ge.UNITS_PIXELS, evt.getClientY(), ge.UNITS_PIXELS, ge.HIT_TEST_BUILDINGS);
  if (hitTestResult) {
    buildingsPlacemark = makePlacemark(hitTestResult.getLatitude(), hitTestResult.getLongitude(),
        hitTestResult.getAltitude(), ge.ALTITUDE_ABSOLUTE, 'B');
    ge.getFeatures().appendChild(buildingsPlacemark);
  }
});

function makePlacemark(lat, lng, alt, altMode, iconStr) {  
  var icon = ge.createIcon('');
  icon.setHref('http://maps.google.com/mapfiles/kml/paddle/' + iconStr + '.png');
  
  var style = ge.createStyle('');
  style.getIconStyle().setIcon(icon);
  style.getIconStyle().getHotSpot().set(0.5, ge.UNITS_FRACTION, 0, ge.UNITS_FRACTION);
  
  var pt = ge.createPoint('');
  pt.set(lat, lng, alt, altMode, false, false);
  
  var pm = ge.createPlacemark('');
  pm.setGeometry(pt);
  pm.setStyleSelector(style);
  
  return pm;
}