This paper is a contribution to the Accessible Way-Finding Using Web Technologies. It was not developed by the W3C Web Accessibility Initiative (WAI) and does not necessarily represent the consensus view of W3C staff, participants, or members.
Extended Abstract for the RDWG Symposium on Accessible Way-Finding Using Web Technologies
Accessible Wayfinding Ontologies for People with Disabilities
- Jessica G. Benner. University of Pittsburgh, Pittsburgh PA, firstname.lastname@example.org
- Hassan A. Karimi. University of Pittsburgh, Pittsburgh PA, email@example.com
Existing pedestrian wayfinding services (e.g., Google Maps Walking-Beta) do not support accessible wayfinding for people with disabilities (PWDs) partly due to the lack of information about accessibility of the environment in their databases. In order to develop services that support accessible wayfinding for PWDs, databases that contain accessibility information and methods describing how accessibility information is used and preferred for wayfinding by PWDs are required. In this paper, we argue that accessible wayfinding ontologies, on one hand, are an effective means of conceptualizing the accessibility of the built environment, and on the other hand, can help understand how PWDs interact with the environment during wayfinding.
Ontologies are explicit, shared conceptualizations of a domain . The use of ontologies today is pervasive ‘due to the enormous need for shared concepts in the distributed work of the web’ . Accessible wayfinding ontologies can enable designers of new pedestrian navigation services to develop new services that are effective in addressing the wayfinding challenges of PWDs and that are interoperable (allow exchange of accessibility information among different navigation services). Current ontologies concerning pedestrian navigation (some of which focus on accessibility) are designed to generate route instructions for pedestrians [2, 3, 4](Paepen and Engelen 2006); represent landmarks for hiking ; select routes among a set of candidate routes ; list requirements to determine feasible networks [5, 7]; and embed semantic information for assistance .
Table 1 shows a summary of our review on current ontologies for pedestrian wayfinding and navigation. As shown in this table, while currently there are ontologies that address some aspects of accessible wayfinding of PWDs, there is a gap in research in that none is generalized and comprehensive enough to address the various mobility challenges faced by PWDs in different environments.
|Name||Purpose||Use||Environmental Features||Definition of Accessibility||Source of knowledge|
(Paepen and Engelen 2006)
|To create language and direction independent navigation instructions||To translate instructions into new languages and reverse the direction of instructions||Landmarks||Not focused on accessibility||Walk guides|
|Landmark Ontology for Hiking
|To formally represent landmarks for hiking||To automate use of landmarks in the Terrain Navigator application||Landmarks, hiking trails||Focus on older adults (limited walking, using wheelchair)||Interviews, empirical study with hikers, map legends|
[2, 3, 4]
|To define pedestrian information needs and service and data specifications||To identify the core elements of route instructions for pedestrians||Conceptual: distance, landmarks, map. Physical: streets, buildings, green areas||None: they note adaptive services for ‘handicapped persons’ as future work||Existing car navigation services and literature on human cognitive maps for pedestrians|
|Indoor Navigation Ontology (INO)
|To describe navigation paths||To enable reasoning for route selection||Hallway paths, points-of-interest, obstacles||Based on physical and perceptive capabilities of individual users||Unknown|
|To model indoor networks and features||To provide routes within a building that meet the special needs and preferences of individuals||Hallway paths, points-of-interest, transitions||Based on ADA criteria – focus on mobility and vision communities||ADA Standards|
|Ontology for Structure Description
|To describe a structure (building)||To allow users to point a device at an object and receive a semantic description||Floor, wall, room, building||None – even though target population is the blind community||Unknown|
In this paper, we propose accessible wayfinding ontologies using four of the ontology development requirements suggested by Suarez-Figueroa and Gomez-Perez : purpose, scope, end users, intended uses. The purpose is to conceptualize the domain of accessible wayfinding and to enable navigation service providers and urban planners to understand how PWD interact with indoor and outdoor environments during wayfinding. The scope is a detailed description of indoor and outdoor pathways and entrances, a description of the wayfinding needs of PWDs, and the interaction between PWDs and pathways and entrances. The end users include developers of accessibility maps, developers of services for assisting PWDs for their wayfinding requests, and urban planners who evaluate the accessibility of the built environment, among others. The intended uses include evaluation of the accessibility of the built environment, updating navigation databases with accessibility information, and an understanding of the wayfinding needs and preferences of PWDs.
Determining what accessibility information should be considered for PWDs wayfinding is challenging in that:
- (a) there are a variety of obstacles both in outdoors and indoors that impede PWDs wayfinding;
- (b) each PWD is faced with a different set of difficulties for wayfinding;
- (c) some obstacles are situational or ephemeral;
- (d) not all obstacles are easily expressed or tangible and mapped into accessibility for wayfinding; and
- (e) there is currently a lack of common agreed upon standards for accessible wayfinding.
Specific recommendations for how accessible wayfinding ontologies should be created include:
Standards such as those developed by the Americans with Disabilities Act , which are focused on accessibility of the built environment, should be considered as a foundation to derive accessible wayfinding. Of the existing pedestrian navigation ontologies, ONALIN [5, 7] include ADA criteria.
Participation of people with disabilities
The inclusion of PWDs in the process of creating wayfinding ontologies is critical so that systems and services based on them can assist their mobility. Including PWDs is the most effective way to understand and analyze how they experience accessibility and to uncover the challenges they encounter during wayfinding. Of the existing ontologies, none include PWDs in their design, and only one  include people in their design.
Semantics of Accessibility
Kavouras and Kokla  note two perspectives, ontological and design/implementation, in which ontologies are commonly created. The former focuses on conceptualization and enables semantic integration, while the latter's focus is on formalizing and associating data or information. Existing ontologies for wayfinding and navigation, except Sarjakoski et al. , include a mixture of both perspectives. A shortcoming of the existing wayfinding ontologies is that they are more about the semantics of geographic space than the semantics of accessibility of the built environment. To overcome this shortcoming, there is a need to pay special attention to the semantics of accessibility of the built environment in creating accessible wayfinding for PWDs.
6. Future Research
Future work includes creating ontologies suitable for accessible outdoor wayfinding and indoor wayfinding of PWDs by taking into account the three recommendations above.
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