    context.strokeStyle = TRACKING_RING_STROKING_STYLE;
        context.beginPath();
        context.arc(polygon.x, polygon.y, polygon.radius +
            TRACKING_RING_MARGIN, 0, Math.PI*2, false);
        context.stroke();
        context.restore();
    }

    function drawRotationAnnotations(loc) {
        drawCentroid(polygonRotating);
        drawCentroidGuidewire(loc, polygonRotating);

        drawTrackingDial(polygonRotating);
        drawDegreeOuterDial(polygonRotating);
        context.fillStyle 