1. A method for estimating X-ray pose, comprising: resolving a coordinate system in a single 2D X-ray image of a material under investigation; and applying intensity-based 2D/3D registration without segmentation to the coordinate system 2D X-ray image and an ultrasound image volume of the material under investigation or a known 3D model of the coordinate system; wherein the coordinate system is associated with the material under investigation; wherein the intensity-based 2D/3D registration yields an estimate of the X-ray pose.