When you create a Field from Point Map, there is an option for Interpolation and Extrapolation. Watch the video (5:27) below to learn more about the different options and how they affect the data.
Linear Interpolation: The linear middle ground based on how far away it is from the point and the other closest point.
Nearest Point: Looks for the closest point that is referenced in the point map and sets that value equal to there. Creates a Voronoi pattern, because it creates regions where there are closest volumes to a point.
Natural: A smoothened version of linear interpolation. Allows you to see quadratic patterns in the interpolation.
Barycentric: Should be used for points in a tetrahedral mesh, like FEA results. Linearly interpolates between the three closest points.
Linear: Looks at the trend inside the interpolation region and extends it outward.
Nearest: Equal to whatever the closest value is at the edge.
Exponential: Looks at the next two points going in and develops a trend that extends out
None: Sets values equal to zero outside. This is the most common option.