Simulations of cardiac electrical activity are generally computed in idealized or generic domains. We have developed a semi-automated technique for imaging an extended volume of cardiac ventricular tissue at a resolution of approximately 1 microm, and constructing from those images a geometric and structural model with 10 microm resolution suitable for solving the bidomain equations. This technique enables experimental modeling and computer simulation to be integrated by constructing a tissue-specific structural model in less than one week. We demonstrate the use of this procedure applied to a sample of rat ventricle.