during cardiac mapping in which a mapping catheter is inserted into a heart, receiving a plurality of recordings from the mapping catheter, each recording comprising a voltage, and spatial coordinates of a recording site within the heart indicative of an electrode position of the mapping catheter at a time of acquisition of said voltage;

constructing a three-dimensional surface of the heart based on the spatial coordinates of each recording site, wherein the three-dimensional surface of the heart comprises an outer mesh surface and an inner mesh surface wherein the outer mesh surface is calculated using a first algorithm and the inner mesh surface is calculated using a second algorithm;

performing surface analysis of the constructed three-dimensional surface to determine off-surface points in the plurality of recordings wherein each off-surface point corresponds to a recording from the plurality of recordings which does not lie on the three-dimensional surface; and

selectively moving at least some of the off-surface points to the three-dimensional surface based on a predefined threshold.