Elements of Geospatial Images to Support Cognitive Tasks in Wayfinding
1Kettunen, P.; 2Sarjakoski, T.; 3Sarjakoski, L.T.
Geospatial images (abbr. geo-images), such as topographic maps and aerial photographs, often serve as an initial exposure to an unfamiliar environment for wayfinders, and so establish the basis of spatial knowledge used for navigation in the environment. The supply of easily available geo-images has exploded in the 21st century due to the rapid development of geospatial data acquisition and visualization techniques. However, the experimental research on the usability of the images in different tasks has not followed at the same pace. Particularly, the extensive research and methods of spatial cognition have not yet been fully considered when addressing the users' needs. For instance, three-dimensional cartographic maps, oblique aerial photographs, and panoramic street views remain under-investigated from the cognitive perspective. The gap between the technological development and cognitive suitability is addressed in the present article. This article summarizes an ensemble of three studies that investigated the support of various elements of geo-images for the human acquisition of spatial knowledge in wayfinding environments: 1. Evaluation of geospatial images in regard to the acquisition of spatial wayfinding knowledge. An evaluation framework was created based on a comprehensive literature review that considered previous experimental spatial cognition studies about spatial knowledge. Three types of spatial knowledge were taken into account: landmark knowledge, route knowledge and configuration knowledge. 2. Experimental cartographic rendering of a three-dimensional relief map. A 3D map was rendered using a cartographically beneficial oblique parallel projection, directed lighting, hypsographic coloring and contours as well as equilatelar and equiangular grid. Different values for parameters were studied in order to examine the effects of parameters on the map view. 3. An eye-tracking experiment of elevation visualization techniques in topographic maps. In total, 26 subjects carried out visual search, area selection and route planning tasks while viewing topographic maps with different elevation visualizations: contours only, contours and relief shading, and an oblique view derived from the experimental rendering study (N:o 2). The eye movements of the subjects were registered and analysed in order to study differences between visualizations. The results of the studies highlighted the importance of vertical and elevation features in geo-images for wayfinding. Images with the aerial oblique vantage point were evaluated the most supportive for wayfinding because they provide the user simultaneously with landmark, route and configuration types of spatial knowledge, so that the user can acquire a highly developed understanding about the environment and navigate succesfully through a route. The determination of the parameters for the experimental 3D map showed a high dependency of the parameters on the region under rendering. The eye-tracking experiment with a similar view indicated relatively high cognitive load while watching the oblique parallel view, which seemed to be caused by the elevated visual clutter in the view due to the triangular grid. However, the oblique parallel view showed the highest ease of watching in the tasks of free exploration, which suggests it to be potential to be developed further. The relief shading with contours was found the most beneficial of the studied elevation visualizations based on the performance and eye movement measures. In summary, the presented ensemble of studies showed and itemized the importance of representation of vertical and elevation features in geospatial images for wayfinding by taking advantage of the methods and previous results of spatial cognition research.
Geospatial image; Wayfinding; ElevationFull Text ()