@Override
    public void init(final int zLevel) {
        defaultZLevel = Math.max(0, zLevel);

        //initialize marker layer stuff
        final Bitmap bitmap = new AndroidBitmap(BitmapFactory.decodeResource(CgeoApplication.getInstance().getResources(), R.drawable.cgeo_notification));
        defaultMarkerSymbol = new MarkerSymbol(bitmap, MarkerSymbol.HotspotPlace.BOTTOM_CENTER, true);

    }
mimics {@link #removeItem(MarkerInterface)} but w/o calling 'populate'
main/src/main/java/cgeo/geocaching/unifiedmap/geoitemlayer/MapsforgeVtmGeoItemLayer.java