Our aim is to develop a framework to validate 3-D computer models of cardiac electrophysiology using measurements of action potential obtained via optical imaging (based on voltage-sensitive fluorescence), and heart anatomy and fiber directions which are obtained from magnetic resonance imaging (MRI). In this paper we present preliminary results of this novel framework using a healthy porcine heart ex vivo model and the Aliev & Panfilov mathematical model. This experimental setup will facilitate the testing, validation and adjustment of computational models prior to their integration into clinical applications.