Values of a physiologic parameter at respective measured points in a heartare obtained. A 3-dimensional model of the heart is constructed, whichincludesfirst spatial elements that include the measured points and second spatialelements that do not include the measured points. The values of the parameterinthe second spatial elements are interpolated and regional densities of themeasured points in the model determined. The values of the parameter at thefirstspatial elements and the second spatial elements are displayed on a functionalmap of the heart, and a graphical characteristic of the map is modifiedresponsively to the regional densities.