Mark a spot with box in Google Maps Street View

Question

i want to mark a spot in google street view with transparent box and it needs to be fixed with image as it rotates around. like marking a plant or house.

I have tried to implement it but my equation needs refinement.

I would really appreciate if anyone could help me with it. Link is below.

http://goo.gl/eudjE1

    google.maps.event.addListener(panorama, 'pov_changed', function (cluster) {

        var newHeading = panorama.getPov().heading % 360;
        var newPitch = panorama.getPov().pitch;
        changeXY($("#box-1"), newHeading, newPitch);
    });

    function changeXY(ctrl, heading, pitch) {
        var w = $("#map-canvas").width() / 2;
        var h = $("#map-canvas").height() / 2;

        var pos = {
            left: (w * Math.sin(d2r(heading))),
            top: (h * Math.cos(d2r(pitch)))
        }

        $(ctrl).css("left", pos.left);
        //$(ctrl).css("top", pos.top);
    }
    function d2r(t) {
        return t / 180 * Math.PI
    }