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Conference Papers Year : 2021

Mapping road crossings for visually impaired people


Tactile maps are an important source of information to communicate spatial knowledge and facilitate the mobility of people with visual impairment (PVIs) (Espinosa et al., 1998). With map representations that correspond well to the important environmental features perceived by the PVIs (Lobben & Lawrence, 2012), potentially enhanced with audio and interactions (Brock et al., 2015), the maps can efficiently assist them to acquire the necessary spatial knowledge for their journey. But the maps are often not available for road crossings, especially complex ones with traffic islands, which are particularly challenging in the journeys of PVIs. Most existing mobility-related automated tactile mapping tools work on the scale of neighborhoods with more emphasis on road networks and building footprints (Minatani et al., 2010 ; Štampach & Mulíčková, 2016; Touya et al., 2019), and even when it's possible to zoom in to a road crossing level (Červenka et al., 2016), there is little detailed information about the layout of the road crossings regarding e.g. traffic islands or pedestrian crossings that are critical to the execution of a safe cross (Wiener et al., 2010). These road crossing maps are still being hand-made by professionals in a tailored and time-consuming manner. To better facilitate PVIs mobility around the road crossings with (semi-)automated mapping, we still need to better understand how spatial knowledge could be efficiently communicated through non-visual manners in this particular situation, including how the crossing is perceived, mentally represented, and related with the tactile representations. In the framework of ANR ActivMAP project, inspired by the practice in handmade tactile mobility maps, we aim to explore the design possibilities for tactile maps for road crossing and produce them in a (semi-)automated manner in an experimental approach. Our short-term objective is to produce a simple map with less complex geometries while still presenting the necessary information related to a road crossing to facilitate the PVIs’ understanding of its layout. We conducted the experiment with OpenStreetMap data, following the tactile graphic guidelines (e.g. The Braille Authority of North America 2010). Considering the potential use case of the map (portable), the scale of the map is initially set at 1:1000, intended to be printed on microcapsule paper of A4 or A5 size. Based on available handmade maps made by professional tactile document makers and orientation and mobility instructors, we initially identified the objects to be included in the map as streets, traffic islands, pedestrian crossings, building blocks, and sidewalks. The prototype pipeline of our experiment follows a classical cartographic pipeline in terms of geometry processing and styling. The geometry processing mainly consists of the transformation and generalization of the geometries existing in the dataset (displacement and transformation of the streets, generalization of building blocks, transformation of pedestrian crossing points), and the estimations of object geometries that are not present in the datasets (e.g. traffic islands and sidewalks). Since there is no standard regarding tactile symbolizations for objects on the road crossing level, the last step of our pipeline consists of exploring multiple possible styling options, as observed from various handmade maps. The pipeline is implemented in QGIS.
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hal-03484068 , version 1 (26-09-2022)





Yuhao Jiang, María Jesús Lobo, Sidonie Christophe, Christophe Jouffrais. Mapping road crossings for visually impaired people. 30th International Cartographic Conference (ICC 2021), ICA : International Cartographic Association, Dec 2021, Florence, Italy. pp.1-2, ⟨10.5194/ica-abs-3-127-2021⟩. ⟨hal-03484068⟩
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