This method of interpolation involves simple averaging using a moving window (usually a circle or ellipse). For each interpolated grid point a circle of specified radius (or an ellipse defined with semi-major axis, semi-minor axis and orientation angle) is placed with its center at the grid point. All data points that lie within the window are averaged to produce the estimate at the grid point. If there are no data points within the window the selected point has no value assigned to it. The method is thus heavily dependent on the choice of window size and orientation, and the density of source data points. The resulting surface is simple and fast to generate, but may exhibit discontinuities.