A method for 3D visualization of a cardiac-ablation balloon in a region of a heart within a predefined 3D space using single-plane fluoroscopy, the method comprising: (1) placing, inflating and positioning the balloon into the region, the balloon having a radio-opaque marker and central catheter portion； (2) capturing first-view images from a first angle； (3) capturing second-view images from a different angle different； (4) selecting first-view and second-view images having a minimum difference between the cardio-respiratory phases of the two images； (5) identifying the marker in the two images； (6) placing orientation markers in the two images where the central catheter portion intersects the projected balloon image farthest from the marker； (7) associating the markers and the orientation markers in two images, respectively； (8) determining 3D balloon location and orientation； (9) and inserting a 3D balloon model into the predefined space to generate the 3D visualization.
