Experimental Evaluation of Multi-scale Tactile Maps Created with SIM, a Web App for Indoor Map Authoring
Viet Trinh, Roberto Manduchi, Nicholas A. Giudice · 2023 · ACM Transactions on Accessible Computing · doi:10.1145/3590775
Summary
This paper introduces Semantic Interior Mapology (SIM), a web application that democratizes tactile map creation by allowing anyone to trace a floor plan image and automatically generate embossable tactile maps at multiple scales. Unlike outdoor environments where services like TMAP exist for on-demand tactile map generation, indoor spaces have lacked equivalent tools—a gap SIM addresses. SIM works in two stages: (1) vectorization of a floor plan through an intuitive tracing interface that generates spatial primitives (spaces, walls, entrances, point features, extended features), and (2) automatic conversion to embossable format using standardized tactile symbols following BANA (Braille Authority of North America) guidelines. Maps can be embossed on Braille paper or rendered on microcapsule paper using a regular printer with a tactile image enhancer. A key innovation is multi-scale rendering at three levels: Structure (bird's-eye view of entire building, no labels), Section (portion of building with room numbers and door symbols), and Room (individual room showing furniture and features). This addresses the fundamental challenge that tactile maps have lower spatial resolution than visual maps, making it impossible to show all details at once. The design was informed by a focus group with seven blind participants, who provided feedback on symbol choices and scale preferences.
Key findings
A user study with 10 blind participants (ages 50-73, median 66) evaluated maps of a real campus building at Section and Room scales. Tasks included map exploration questions, pointing to locations from imagined positions, cross-map path finding, and turn direction/walking orientation during imagined traversal. The study was conducted remotely via phone/Zoom using a think-aloud protocol. Results were strongly positive: all participants correctly answered map exploration questions (except one about rooms with two doors where most participants missed some). Path finding was successful—all participants found walkable routes between requested locations, though some paths were longer than optimal. For pointing tasks, 89% of errors came from just three participants, suggesting the maps support accurate spatial learning for most users. The most cognitively demanding task—maintaining both egocentric (turn left/right) and allocentric (now facing East) orientation while imagining walking a path—was completed successfully by most participants with only two having consistent difficulty. Exit questionnaire scores showed median ratings of 5 (highest) on all seven Likert items, including map readability, symbol clarity, and ease of transitioning between scales. Notably, participants successfully integrated spatial knowledge across the two map scales, consolidating information into a coherent cognitive map.
Relevance
This research addresses a significant gap in accessible wayfinding: while outdoor tactile maps have established production pipelines (TMAP, OpenStreetMap-based tools), indoor maps have traditionally required specialized expertise and manual creation. SIM's web-based approach means O&M instructors, building managers, or family members could create tactile maps for any building with an available floor plan. The multi-scale approach has direct implications for tactile graphics design generally—rather than trying to fit all information on one map (resulting in clutter) or creating many separate pages (requiring cognitive integration), SIM's hierarchical scales let users choose the appropriate detail level for their task. The finding that only ~10% of blind people read Braille reinforces the importance of tactile symbols over text labels for universal accessibility. For practitioners, SIM demonstrates that pre-journey spatial learning from tactile maps is effective—participants built accurate mental models of unfamiliar spaces. This supports the case for providing tactile maps before visits to hospitals, schools, shopping centers, and other complex indoor environments where real-time navigation assistance may be insufficient for true spatial understanding.
Tags: tactile maps · indoor navigation · blindness · spatial learning · orientation and mobility · wayfinding · assistive technology · map authoring
Standards referenced: BANA Guidelines for Tactile Graphics