MGDM is an efficient level set framework for multi-object segmentation. Its representation inherently prevents overlaps and gaps and it readily preserves object topology and object relationships. MGDM is efficient, storing only a fixed number of functions for any number of objects, and therefore scales well to segmentation problems with many classes and large images. It's representation also avoids some instabilities in other multi-class level set methods. MGDM is cross-platform; MATLAB wrappers, Java source and API are provided, with MIPAV plugins forthcoming.