Indoor Human Navigation Systems: A Survey <s> Introduction <s> This article reports on an experiment undertaken to test the spatiocognitive competence of the visually impaired population in regard to wayfinding. The test consisted of eight basic wayfinding tasks, each representing a particular spatio-cognitive operation. The tasks were executed in a labyrinthian layout allowing for control of the difficulty level of the tasks and limiting extraneous perceptual factors, which tended to interfere with the measure of spatio-cognitive abilities. The experimental groups were composed of congenitally totally blind, adventitiously totally blind, and subjects with a weak visual residue; the control was established by a sighted and a sighted blindfolded group. The sample's 18 subjects per group were matched in terms of age, education, and sex. The performance results of the visually impaired groups in all eight tasks led to rejection of any spatio-cognitive deficiency theory. The performance of the congenitally totally blind group, in particular, shows that spatio-cognitive c... <s> BIB001 </s> Indoor Human Navigation Systems: A Survey <s> Introduction <s> We describe some of the results of our program of basic and applied research on navigating without vision. One basic research topic that we have studied extensively is path integration, a form of navigation in which perceived self-motion is integrated over time to obtain an estimate of current position and orientation. In experiments on pathway completion, one test of path integration ability, we have found that subjects who are passively guided over the outbound path without vision exhibit significant errors when attempting to return to the origin but are nevertheless sensitive to turns and segment lengths in the stimulus path. We have also found no major differences in path integration ability among blind and sighted populations. A model we have developed that attributes errors in path integration to errors in encoding the stimulus path is a good beginning toward understanding path integration performance. In other research on path integration, in which optic flow information was manipulated in addition to the proprioceptive and vestibular information of nonvisual locomotion, we have found that optic flow is a weak input to the path integration process. In other basic research, our studies of auditory distance perception in outdoor environments show systematic underestimation of sound source distance. Our applied research has been concerned with developing and evaluating a navigation system for the visually impaired that uses three recent technologies: the Global Positioning System, Geographic Information Systems, and virtual acoustics. Our work shows that there is considerable promise of these three technologies in allowing visually impaired individuals to navigate and learn about unfamiliar environments without the assistance of human guides. <s> BIB002 </s> Indoor Human Navigation Systems: A Survey <s> Introduction <s> Cognitive maps are mental models of the relative locations and attribute phenomena of spatial environments. The ability to form cognitive maps is one of the innate gifts of nature. An absence of this ability can have crippling effect, for example, on the visually impaired. The sense of touch becomes the primary source of forming cognitive maps for the visually impaired. Once formed, cognitive maps provide precise mapping of the physical world so that a visually impaired individual can successfully navigate with minimal assistance. However, traditional mobility training is time consuming, and it is very difficult for the blind to express or revisit the cognitive maps formed after a training session is over. The proposed haptic environment will allow the visually impaired individual to express cognitive maps as 3D surface maps, with two PHANToM force-feedback devices guiding them. The 3D representation can be finetuned by the care-giver, and then felt again by the visually impaired in order to form precise cognitive maps. In addition to voice commentary, a library of pre-existing shapes familiar to the blind will provide orientation and proprioceptive haptic-cues during navigation. A graphical display of cognitive maps will provide feedback to the care-giver or trainer. As the haptic environment can be easily stored and retrieved, the MoVE system will also encourage navigation by the blind at their own convenience, and with family members. <s> BIB003 </s> Indoor Human Navigation Systems: A Survey <s> Introduction <s> Previous studies suggest that humans rely on geometric visual information (hallway structure) rather than non-geometric visual information (eg doors, signs, and lighting) for acquiring cognitive maps of novel indoor layouts. In this study we asked whether visual impairment and age affect reliance on non-geometric visual information for layout learning. We tested three groups of participants—younger (<50 years of age) normally sighted; older (50–70 years of age) normally sighted; and low-vision (people with heterogeneous forms of visual impairment ranging in age from 18 to 67 years). Participants learned target locations in building layouts using four presentation modes: a desktop virtual environment (VE) displaying only geometric cues (sparse VE); a VE displaying both geometric and non-geometric cues (photorealistic VE); a map; and a real building. Layout knowledge was assessed by map drawing and by asking participants to walk to specified targets in the real space. Results indicate that low-vision and ol... <s> BIB004
Human navigation relies on a combination of mobility and orientation skills  . People employ either path integration, where they orient themselves relative to a starting position using proprioceptive data, or landmarkbased navigation, where they rely upon perceptual cues together with an external or cognitive map. Humans may also use a combination of both path integration and landmark-based navigation BIB002 . In general, human navigation in indoor and outdoor environments, is performed by measuring the distance and orientation relative to one or multiple reference points. By periodically measuring the displacement and changes in the orientation (based on body motion and heading) and adding them with the distance and orientation relative to a reference point, such as a landmark, users can estimate their new location and orientation while navigating in an environment. In case of path integration a single reference point is used throughout the navigation, and the location is estimated based on adding all the changes in position and orientation  . In this case a map of environment is not needed  as the individual keeps track of all the changes. In landmark-based navigation, users change from reference points (landmarks) to reference point as they navigate in the environment, considering the relative position of the landmarks. In this case the individual uses a physical or cognitive map of the environment. By recalling the landmarks and their spatial relationships from memory  , their current position and orientation can be estimated based on the distance and angles relative to one or multiple landmarks  . When exploring new environments, path integration is especially useful for exploring new environments where users may build a cognitive map by observing landmarks   . Studies  show that when maps are available, humans will first navigate using a landmark based approach and as successfully map the environment, switch to using path integration. Cognitive mapping is concerned with the process in which humans create a mental map of the environment  . While navigating many decisions need to be made based on our knowledge of the environment that is stored in the cognitive map. While different senses may be used for navigation, vision is the most effective way for creating a cognitive map, as a great level of details about the environment can be acquired in a relatively short time  BIB004 BIB003 . While navigating primarily the visual sense is used to recognize landmarks and assess the distance and orientation to landmarks as to be able to associate them with landmarks that are stored in the cognitive map. In new environments, way finding can be time consuming and may require a considerable amount of attention. This is especially undesirable for emergency crew, such as firefighters or paramedics, as they have to navigate unfamiliar environments on a daily basis often with limited visibility, for example, in case of a fire. Individuals with visual impairments often need the help of sighted people to navigate and cognitively map new environments, which is time consuming and leads to a lower mobility BIB001 . Individuals with cognitive impairments may have difficulty learning new environments and following directions. Assistive systems for human navigation aim to allow their users to safely and efficiently navigate in unfamiliar environments without getting lost by planning the path dynamically based on the user's location and special needs. The functionality of a navigation system must include locating and following the user while navigating in the environment. The location can be used for both planning the path and providing surrounding information. As the user's location is known, the system can find a new path in case the user is lost or an alternative path is needed. The planned path is used to generate and provide directions to a user-specified destination. The advantage of using a navigation system to plan a path is that the path can be optimized based on different user requirements, such as shortest path or safest path for individuals with vision impairments. The system interacts with the user to provide directions and surrounding information. Alternative interaction methods can be used in different cases, such as graphical displays to make it easier to follow directions or haptic interfaces to accommodate noisy environment. Since the location of the user is known, such systems can provide information regarding the user's surroundings, such as the location of obstacles or important landmarks. Over the past decades numerous indoor navigation systems have been developed. This survey paper provides a comprehensive review of technologies used for the different components (localization, path planning, representation, and interaction) of a navigation system. We contrast the different technologies for each component and discuss their benefits and disadvantages with regards to accuracy, cost and usability. Our paper points out several areas for future research, that could help with large scale deployment of indoor navigation systems. This paper is organized as follows: section 2 discusses localizing the user; section 3 planning a path towards a user-provided destination; section 4 creating and representing a map of the environment; and section 5 interacting with the user. Section 6 points out areas for research and the paper is concluded in Section 7.