code: function trimCanvasXY(xy) {
      if( xy.length === 0 ) return;
      var last = xy[xy.length-1], i, point;
  
      var c = 0;
      for( i = xy.length-2; i >= 0; i-- ) {
          point = xy[i];
          if( Math.abs(last.x - point.x) === 0 && Math.abs(last.y - point.y) === 0 ) {
              xy.splice(i, 1);
              c++;
          } else {
              last = point;
          }
      }
  
      if( xy.length <= 1 ) {
          xy.push(last);
          c--;
      }
  }
docs: given an array of geo xy coordinates, make sure each point is at least more than 1px apart