A system for computing local conduction velocity of a cardiac activation wavefront, the system comprising: a multi-electrode catheter having at least one electrode (17, 52, 54, 56) for collecting electrophysiological data points; a conduction velocity processor configured to receive as input a plurality of electrophysiology ("EP") data points collected using the multi-electrode catheter, each EP data point of the plurality of EP data points having a position and a local activation time ("LAT"), and, for a selected EP data point of the plurality of EP data points the conduction velocity processor being configured to: define a neighborhood of EP data points including the selected EP data point and at least two additional EP data points from the plurality of EP data points; compute a plane of positions from least square fits of the positions of the EP data points within the neighborhood of EP data points; compute a plane of LATs from the LATs of EP data points within the neighborhood of EP data points and from least squares fits of the positions of the EP data points; and compute a conduction velocity from an intersection of the plane of positions and the plane of LATs, if the plane of positions and the plane of LATs intersect; and a mapping processor configured to generate a three-dimensional graphical representation of a plurality of conduction velocities computed by the conduction velocity processor. a multi-electrode catheter having at least one electrode (17, 52, 54, 56) for collecting electrophysiological data points; a conduction velocity processor configured to receive as input a plurality of electrophysiology ("EP") data points collected using the multi-electrode catheter, each EP data point of the plurality of EP data points having a position and a local activation time ("LAT"), and, for a selected EP data point of the plurality of EP data points the conduction velocity processor being configured to: define a neighborhood of EP data points including the selected EP data point and at least two additional EP data points from the plurality of EP data points; compute a plane of positions from least square fits of the positions of the EP data points within the neighborhood of EP data points; compute a plane of LATs from the LATs of EP data points within the neighborhood of EP data points and from least squares fits of the positions of the EP data points; and compute a conduction velocity from an intersection of the plane of positions and the plane of LATs, if the plane of positions and the plane of LATs intersect; and define a neighborhood of EP data points including the selected EP data point and at least two additional EP data points from the plurality of EP data points; compute a plane of positions from least square fits of the positions of the EP data points within the neighborhood of EP data points; compute a plane of LATs from the LATs of EP data points within the neighborhood of EP data points and from least squares fits of the positions of the EP data points; and compute a conduction velocity from an intersection of the plane of positions and the plane of LATs, if the plane of positions and the plane of LATs intersect; and a mapping processor configured to generate a three-dimensional graphical representation of a plurality of conduction velocities computed by the conduction velocity processor.