Comment by cambecc

The NCEP data provides only 1º resolution, so bilinear interpolation is used to fill in the gaps. How much interpolation is needed depends on the zoom level and the projection. On top of that, the distortion caused by the projection must be applied to the interpolated wind field. All of these heavy calculations are done up front so the animation can be as fast as possible. So each time the orientation of the globe changes, we have to redo the calculations.