An apparatus includes a shaft, a flexible distal-endassembly, two or more sensing-electrodes, and a fiber-opticshape sensor. The shaft is configured for insertion into a bodyof a patient. The flexible distal-end assembly is fitted at adistal end of the shaft. The two or more sensing-electrodes aredisposed over the distal-end assembly and are configured togenerate signals indicative of positions of the sensing-electrodesin the body. The fiber-optic shape sensor is coupledto a portion of the distal-end assembly, wherein the two ormore sensing-electrodes have a-priori known distances from aknown location over the fiber-optic shape sensor, and whereinthe fiber-optic shape sensor is configured to provide anindication of a spatial deformation of the flexible distal-endassembly.
