Comparison techniques utilized in spatial 3D and 4D data visualizations: A survey and future directions.

•An exhaustive survey of 3D/4D comparative visualization is done.•A taxonomy of 3D/4D comparative visualization techniques is proposed.•Four fundamental approaches were identified in literature with discussion of most interesting extensions.•The number of data instances supported in the visualizations is small.•Hybrid designs and visualization in VR are promising next steps for research.