A method of image data interpolation. The method includes obtaining transform data associated with a plurality of sampling points, each sampling point located on a boundary of a region. The transform data is processed to generate additional transform data associated with an additional sampling point located on a boundary of a subregion of the region. An interpolation process is performed. The interpolation process includes processing image data associated with a point within the subregion with the additional transform data, thereby generating interpolated image data representative of an interpolated data value at the point. This patent application further relates to a method including obtaining transform data associated with points corresponding to a surface of a region and generating additional transform data associated with at least one interior point of the region. Image data associated with a further interior point of the region is interpolated using at least the additional transform data.