Scalar Subdivision Schemes and Box Splines
For researchers in approximation theory and geometric modeling, this work offers a theoretical foundation for analyzing multivariate subdivision schemes, though it is incremental as it extends known univariate results to the multivariate case.
The paper characterizes the mask symbols of scalar multivariate subdivision schemes with dilation matrix 2I satisfying sum rules of order k, showing they are linear combinations of shifted box spline generators. This provides a systematic framework for studying subdivision schemes, linking box spline smoothness with polynomial reproduction order.
We study scalar $d$-variate subdivision schemes, with dilation matrix 2I, satisfying the sum rules of order $k$. Using the results of Möller and Sauer, stated for general expanding dilation matrices, we characterize the structure of the mask symbols of such schemes by showing that they must be linear combinations of shifted box spline generators of some quotient polynomial ideal. The directions of the corresponding box splines are columns of certain unimodular matrices. The quotient ideal is determined by the given order of the sum rules or, equivalently, by the order of the zero conditions. The results presented in this paper open a way to a systematic study of subdivision schemes, since box spline subdivisions turn out to be the building blocks of any reasonable multivariate subdivision scheme. As in the univariate case, the characterization we give is the proper way of matching the smoothness of the box spline building blocks with the order of polynomial reproduction of the corresponding subdivision scheme. However, due to the interaction of the building blocks, convergence and smoothness properties may change, if several convergent schemes are combined.