Interactive shearing for terrain visualization: an expert study

Interpreting terrain in traditional 2D maps can be challenging. However, recent work has shown how interactive shearing of terrain can help users better understand topography and extract elevation information from a map. Using this approach, user input - paired with existing interactions such as pan and zoom - triggers brief ephemeral shearing animations that expose depth and shape information in terrain maps. The animations use motion to enhance the perception of depth and convey the impression of a shaking jelly model that oscillates until it comes to rest. However, it is still unclear how the parameters of these animations impact the effectiveness of the method or if the animations may have negative side effects. Moreover, it is unknown whether interactive relief shearing is accessible enough to be used in common web maps. To investigate these questions, we conducted a user study with 49 cartographers and visualization experts. These experts interactively configured shearing animations and assessed the technique's usability and applicability. To create a platform for the user study and demonstrate that interactive shearing of terrain is technically feasible in browsers, we implemented a web map with interactive shearing animations. All experts found that interactive relief shearing made it easier to see differences in elevation on orthophoto maps. Future web maps could include shearing animations, making it easier for viewers to interpret terrain and see differences in elevation.