1. A method for x-ray pose recovery during an endoscopic procedure, comprising the steps of: taking an x-ray fluoroscopic image with a C-arm at a first C-arm pose, capturing a region of an endoscope with fiducials thereon as a two dimensional projection of a three dimensional curve of the region of the endoscope with fiducials thereon; moving the C-arm from the first pose to a second pose at another viewing angle while maintaining the position of the endoscope; taking another an x-ray fluoroscopic image with the C-arm at the second C-arm pose, capturing the region of the endoscope with the fiducials thereon as another two dimensional projection of a three dimensional curve of the region of the endoscope with fiducials thereon; determining the location of the fiducials on each two-dimensional fluoroscopic image using segmentation methods; and performing an iterative optimization using the two two-dimensional projections of the three dimensional curve of the region of the endoscope with fiducials thereon to determine the three dimensional translation and rotation of the C-arm from the first x-ray pose to the second x-ray pose.