2D treemaps are a space-filling visualization technique that facilitate exploration of non-spatial, attributed, tree-structured data using the visual variables size and color. In extension thereto, 2.5D treemaps introduce height for additional information display. This extension entails challenges such as increased rendering effort, occlusion, or the need for navigation techniques that counterbalance the advantages of 2D treemaps to a certain degree.
This paper presents a novel technique for combining 2D and 2.5D treemaps using multi-perspective views to leverage the advantages of both treemap types. It enables a new form of overview+detail visualization for complex treemaps and contributes new concepts for real-time rendering of and interaction with mixed-projection treemaps. The technique operates by tilting up inner nodes using affine transformations and animated state transitions. The mixed use of orthogonal and perspective projections is discussed and application examples that facilitate exploration of multi-variate data and benefit from the reduced interaction overhead are demonstrated.