Showing posts with label frames of reference. Show all posts
Showing posts with label frames of reference. Show all posts

Tuesday, 21 May 2013

Can Virtual Reality Provide Digital Maps To Blind Sailors? A Case Study

Jacobson, R.D., Simonnet, M., Vieilledent, S. and Tisseau, J. (2009) Can Virtual Reality Provide Digital Maps To Blind Sailors? A Case Study. Proceedings of the International Cartographic Congress, 15-21 November 2009, Santiago, Chile. 10pp.

Abstract
This paper presents information about “SeaTouch” a virtual haptic and auditory interface to digital Maritime Charts to facilitate blind sailors to prepare for ocean voyages, and ultimately to navigate autonomously while at sea. It has been shown that blind people mainly encode space relative to their body. But mastering space consists of coordinating body and environmental reference points. Tactile maps are powerful tools to help them to encode spatial information. However only digital charts an be updated during an ocean voyageand they very often the only alternative is through conventional printed media. Virtual reality can present information using auditory and haptic interfaces. Previous work has shown that virtual navigation facilitates the ability to acquire spatial knowledge. The construction of spatial representations from physical contact of individuals with their environment, the use of Euclidean geometry seems to facilitate mental processing about space. However, navigation takes great advantage of matching ego- and allo-centered spatial frames of
reference to move and locate in surroundings. Blindness does not indicate a lack of comprehension of spatial concepts, but it leads people to encounter difficulties in perceiving and updating information about the environment. Without access to distant landmarks that are available to people with sight, blind people tend to encode spatial relations in an ego-centered spatial frame of reference. On the contrary, tactile maps and appropriate exploration strategies allow them to build holistic configural representations in an allo-centered spatial frame of reference. However,  position updating during navigation remains particularly complicated without vision. Virtual reality techniques can provide a virtual environment to manage and explore their surroundings. Haptic and auditory interfaces provide blind people with an immersive virtual navigation experience. In order to help blind sailors to coordinate ego- and allo-centered spatial frames of reference, we conceived SeaTouch. This haptic and auditory software is adapted so that blind sailors are able to
set up and simulate their itineraries before sailing navigation. In our first experimental condition, we compare spatial representations built by six blind sailors during the exploration of a tactile map and the virtual map of SeaTouch. Results show that these two conditions were equivalent. In our second experimental condition, we focused on the conditions which favour the transfer of spatial knowledge from a virtual to a real environment. In this respect, blind sailors performed a virtual navigation in‘Northing mode’, where the ship moves on the map, and in‘Heading mode’, where the map shifts around the sailboat. No significant difference appears. This reveals that the most important factor for the blind sailors to locate themselves in the real environment is the orientation of the maps during the initial encoding time. However, we noticed that the subjects who got lost in the virtual environment in northing condition slightly improved their performances in the real environment. The analysis of the exploratory movements on the map are congruent with a previous model of coordination of spatial frames of reference. Moreover, beyond the direct benefits of SeaTouch for the navigation of blind sailors, this study offers some new insight to facilitate understanding of non visual spatial cognition. More specifically the cognitively complex task of the coordination and integration of ego and allocentered spatial frames of reference. In summary the research aims at measuring if a blind sailor can learn a maritime environment with a virtual map as well as with a tactile map. The results tend to confirm this, and suggest pursuing investigations with non visual virtual navigation. Here we present the initial results with
one participant.

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