Evaluation of Multi-Level Cognitive Maps for Supporting Between-Floor Spatial Behavior in Complex Indoor Environments

People often become disoriented when navigating in complex, multi-level buildings. To efficiently find destinations located on different floors, navigators must refer to a globally coherent mental representation of the multi-level environment, which is termed a multi-level cognitive map. However, there is a surprising dearth of research into underlying theories of why integrating multi-level spatial knowledge into a multi-level cognitive map is so challenging and error-prone for humans. This overarching problem is the core motivation of this dissertation. We address this vexing problem in a two-pronged approach combining study of both basic and applied research questions. Of theoretical interest, we investigate questions about how multi-level built environments are learned and structured in memory. The concept of multi-level cognitive maps and a framework of multi-level cognitive map development are provided. We then conducted a set of empirical experiments to evaluate the effects of several environmental factors on users’ development of multi-level cognitive maps. The findings of these studies provide important design guidelines that can be used by architects and help to better understand the research question of why people get lost in buildings. Related to application, we investigate questions about how to design user-friendly visualization interfaces that augment users’ capability to form multi-level cognitive maps. An important finding of this dissertation is that increasing visual access with an X-ray-like visualization interface is effective for overcoming the disadvantage of limited visual access in built environments and assists the development of multi-level cognitive maps. These findings provide important human-computer interaction (HCI) guidelines for visualization techniques to be used in future indoor navigation systems. In sum, this dissertation adopts an interdisciplinary approach, combining theories from the fields of spatial cognition, information visualization, and HCI, addressing a long-standing and ubiquitous problem faced by anyone who navigates indoors: why do people get lost inside multi-level buildings. Results provide both theoretical and applied levels of knowledge generation and explanation, as well as contribute to the growing field of real-time indoor navigation systems

Vertical Color Maps: A Data Independent Alternative to Floor Plan Maps

Location sharing in indoor environments is limited by the sparse availability of indoor positioning and lack of geographical building data. Recently, several solutions have begun to implement digital maps for use in indoor space. The map design is often a variant of floor-plan maps. Whereas massive databases and GIS exist for outdoor use, the majority of indoor environments are not yet available in a consistent digital format. This dearth of indoor maps is problematic, as navigating multistorey buildings is known to create greater difficulty in maintaining spatial orientation and developing accurate cognitive maps. The development of standardized, more intuitive indoor maps can address this vexing problem. The authors therefore present an alternative solution to current indoor map design that explores the possibility of using colour to represent the vertical dimension on the map. Importantly, this solution is independent of existing geographical building data. The new design is hypothesized to do a better job than existing solutions of facilitating the integration of indoor spaces. Findings from a human experiment with 251 participants demonstrate that the vertical colour map is a valid alternative to the regular floor-plan map

The effect of navigation method and visual display on distance perception in a large-scale virtual building

Immersive virtual reality (VR) technology has become a popular method for fundamental and applied spatial cognition research. One challenge researchers face is emulating walking in a large-scale virtual space although the user is in fact in a small physical space. To address this, a variety of movement interfaces in VR have been proposed, from traditional joysticks to teleportation and omnidirectional treadmills. These movement methods tap into different mental processes of spatial learning during navigation, but their impacts on distance perception remain unclear. In this paper, we investigated the role of visual display, proprioception, and optic flow on distance perception in a large-scale building by manipulating four different movement methods. Eighty participants either walked in a real building, or moved through its virtual replica using one of three movement methods: VR-treadmill, VR-touchpad, and VR-teleportation. Results revealed that, first, visual display played a major role in both perceived and traversed distance estimates but did not impact environmental distance estimates. Second, proprioception and optic flow did not impact the overall accuracy of distance perception, but having only an intermittent optic flow (in the VR-teleportation movement method) impaired the precision of traversed distance estimates. In conclusion, movement method plays a significant role in distance perception but does not impact the configurational knowledge learned in a large-scale real and virtual building, and the VR-touchpad movement method provides an effective interface for navigation in VR.ISSN:1612-4782ISSN:1612-479

A new Multiuser Detection Algorithm Based on Robust Kalman Filtering

AbstractInspired from H∞ robust control technique, this research applies H∞ filtering to Multi-user Detection (MUD), and proposes a new MUD algorithm based on robust Kalman filtering. Because it can rapidly converge when the statistical property of interferences or noises are unknown, this algorithm has better performance than existing blind adapting MUD based Kalman filtering

The effect of crowdedness on human wayfinding and locomotion in a multi-level virtual shopping mall

This study investigates how social and physical environments affect human wayfinding and locomotion behaviors in a virtual multi-level shopping mall. Participants were asked to locate a store inside the virtual building as efficiently as possible. We examined the effects of crowdedness, start floor, and trial number on wayfinding strategies, initial route choices, and locomotion behaviors. The results showed that crowdedness did not affect wayfinding strategies or initial route choices, but did affect locomotion in that participants in the high crowdedness condition were more likely to avoid crowds by moving close to the boundaries of the environment. The results also revealed that participants who started on the second floor were more likely to use the floor strategy than participants who started on the third floor, possibly because of the structure of the virtual building. These results suggest that both physical and social environments can influence multi-level indoor wayfinding

Impact of Drip Irrigation and Nitrogen Fertilization on Soil Microbial Diversity of Spring Maize

Given the shortage of water resources and excessive application of nitrogen fertilizers in irrigated areas, we explored the effect of water–nitrogen coupling on soil microbial diversity in maize fields irrigated using shallow buried droppers. A field experiment (split-plot design) was used with irrigation amounts set at 40%, 50%, and 60% of the conventional amount; furthermore, 13 water and nitrogen coupling treatments were designed. The secondary area was the nitrogen application level, corresponding to 50%, 70%, and the original conventional application amounts. The results showed that the effect of irrigation amount on bacterial community composition was greater than that of nitrogen, whereas the effect of nitrogen on fungi was greater than that on bacteria. No significant difference was detected in the α diversity index or species richness of bacteria and fungi. Available phosphorus and organic carbon contents significantly correlated with the community structure of soil bacteria (p 3 ha−1. With the decrease of irrigation amount, the relative abundance of bacteria and fungi was stable under the treatment of 210 kg ha−1 nitrogen fertilizer. Moreover, the relative abundance of nitrogen-fixing bacteria related to the nitrogen cycle was increased by irrigation of 2000 m3 ha−1 and nitrogen application of 210 kg ha−1. Moderate reduction of subsequent N supply should be as a prior soil management option in a high N input agroecosystem

UV-A Supplement Improved Growth, Antioxidant Capacity, and Anthocyanin Accumulation in Purple Lettuce (<i>Lactuca sativa</i> L.)

This study investigated the impact of various light qualities on the growth, photosynthesis, antioxidant capacity, anthocyanin accumulation and associated gene expression in purple lettuce. The results showed that stem diameter, leaf number and dry mass of purple leaves lettuce increased significantly under white light plus red and blue light (WRB) plus 10 µmol·m−2·s−1 UV-A (SUV1), plus 20 µmol·m−2·s−1 UV-A (SUV2) and plus 30 µmol·m−2·s−1 UV-A (SUV3) treatments compared to white light plus red and blue light (WRB). Leaf expansion decreased with increasing UV-A doses, while fresh leaf mass was higher under SUV1 and SUV2 treatments. Photosynthesis parameters were improved under WRB, SUV1 and SUV2 treatments, with an increase in net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) and a decrease in intercellular carbon dioxide concentration (Ci) under SUV3 treatment. Superoxide radical generation rate, hydrogen peroxide and malondialdehyde (MDA) content and relative conductivity increased significantly under SUV3 treatment. Anthocyanin content increased significantly with increasing doses of UV-A treatment, while related structural gene expression levels were upregulated more significantly by SUV2 and SUV3 treatments than WRB treatment. In summary, moderate UV-A supplementation can enhance the antioxidant system and promote anthocyanin accumulation in purple lettuce. Specifically, WRB plus 20 µmol·m−2·s−1 UV-A (SUV2) is recommended as an optimal light recipe for cultivating purple lettuce in protected horticulture