Multidimensional Synchronous Dataflow (MDSDF) [15][7] is a model of computation that has been proposed for specifying multidimensional multirate signal processing systems such as image and video processing algorithms. The model is an extension of synchronous dataflow (SDF) [14] and has all of the desirable properties of the SDF model such as static schedulability, exposition of data and functional parallelism, and a visually pleasing syntax well suited for block diagram signal processing environments such as Ptolemy [6] and Khoros [13]. However, the MDSDF model as specified in [15] is limited to modeling multidimensional systems sampled on the standard rectangular lattice. Since many multidimensional signals of practical interest are sampled on non-rectangular lattices, for example, 2:1 interlaced video signals, and many multidimensional multirate systems use non-rectangular multirate operators like hexagonal decimators, it is of interest to have models that are capable of representing and simulating such systems. This report describes an extension of the MDSDF model that allows signals on arbitrary sampling lattices to be represented, and that allows the use of non-rectangular downsamplers and upsamplers.