Optimizing the balance between area and orientation distortions for variable-scale maps

Applying a variable scale transformation to maps leads to area distortions of the maps, i.e. enlarging interesting areas on maps to larger scales and shrinking other areas. Such area distortions improve the clarity of the interesting areas. However, it may result in the over-distortion of line orientations so as to reduce map recognition. This article developed an optimization method to correct orientation distortions for variable-scale maps generated by any existing variable scale transformations, while preserving the map clarity as much as possible. The proposed method is tested with the variable-scale resultant maps of two real-life datasets and evaluated by statistical analysis and perceptual tests. The experimental results indicate that the proposed method is able to effectively reduce the orientation distortions so as to improve map recognition, while map clarity has been sufficiently achieved.