Navigation, Pedestrians and Landmarks (Part 3)
At the end of my last blog, I asserted that all solutions for foot-driven navigation could be enhanced by the use of landmarks and by the pedestrian becoming an active part of the localization solution. If you want to be in on the next big stage of Local Search, you need to know about landmarks and their uses – in the past and in the future.
According to the venerable of the Dictionary of Mapping, Charting and Geodetic Terms (a repackaging of a Defense Mapping Agency publication), a landmark is “An object of enough interest or prominence in relation to its surroundings to make it outstanding or to make it useful in determining a location or a direction”. So, we might conclude that a landmark often is a feature or a structure identified by someone for the purpose of solving a navigation-related problem. It is the individual assignment of importance or identity in the landmark selection process that has made using landmarks a difficult and perhaps controversial aspect of foot-driven navigation.
While some landmarks are commonly known, this is not true of the entire class of landmarks, although all landmarks perform a similar function in pedestrian navigation. In most cities, you might find several landmarks that could be recognized by a large number of observers, such as Chicago’s Sears tower (or is that now the Willis Tower?), the John Hancock Building, The Wrigley Building, or Soldier Field. Conversely, if you took these people to Chicago’s suburb of Lincolnshire and asked them to identify the Half Day Inn, the consensual-nature of identification would fare less well.
Maps and Landmarks
On printed maps, for example, the majority of the landmarks shown are either structures or features (such as a golf course or a lake) that can be seen from a car and used as a waypoint for navigating between places. In other cases, landmarks on printed maps reflect well-known locations, such as museums, famous buildings, shopping centers and government centers that might be visited by those touring the area. The majority of landmarks of importance to individuals are not shown on maps. Indeed, the very medium of print publishing acts to preclude incorporation of the places individuals consider landmarks in their attempts to locate themselves in space, or to direct others to their location.
Navigation Devices and Landmarks
Curiously, Personal Navigation Devices and in-car navigation systems, which purport to have the ability to customize maps, make it difficult to use personalized landmarks and personalized routes that reflect these landmarks. In essence, the use of landmarks in navigation systems has not advanced from its passive status in the days that printed maps were the prominent source of route planning. In other words, the number and kinds of “landmarks” shown in digital databases are not robust enough to be of significant assistance to developing a foot-driven navigation system.
More Ideas About Landmarks
It might be useful to consider landmarks as falling into two categories. On the one hand there are commonly agreed prominent or conspicuous structures or features. On the other hand, there are those features or structures that may be identified, or are identifiable, only by a small group, or perhaps even an individual (e.g. for a child, their most important landmarks may be their home, their school and the home of their best friend). From a practical perspective, landmarks can be thought of as whatever identifiable feature or structure is deemed to be of importance to the individual performing the navigation task. It is both the local and personal nature of landmarks that has made using them for providing route guidance to pedestrians so difficult, at least until now.
Help! I’m Lost – The use of mental maps
While working with individually selected landmarks may sound senseless, it is important to note that people who are lost, attempt to assign importance to their surroundings and then search for other information that might help them locate the position of the object to which they are referring.
I am sure that each of you has been on the phone with someone who has become lost while trying to navigate to your location. In order to help position them, you ask if they can describe their location and, then, you attempt to match this description with your mental map of the various paths known to you that are valid approaches to your location.
When the person with whom you are speaking can tell you the street or highway names, the task is quite easy. When they have no idea of the street they are on and cannot see any identifying signs, they begin to describe the environment surrounding them. What the caller is doing is assigning a “landmark status” to the structures or features surrounding them. What you are doing, when trying to locate their position, is comparing their landmarks with your mental map of landmarks relevant to navigating to your location and if that fails, landmarks generally known to you but not related to your position (or perhaps they may be considered unrelated by you).
A Simple Example
So, now, let’s go back to the problem mentioned at the start of this series and try to find the Oinker Bar. Let’s agree that our iPhone was able to find the business listing of the Oinker Bar on Google, complete with a locator map. However, let’s also assume that you get that message that “GPS is unavailable”, so the application cannot “find” you to route you to the location. What to do?
One model of using landmarks for navigation might be that the pedestrian assigns landmark status to a building and attempts to discover information about that building that would help them to establish its locations. Perhaps the building is a business? If so, we should be able to find it with a local search query. Unfortunately, the location appears not be to be a business, so we will have to find some other solution. Well, most printed maps do not offer the type of detail of interest (and certainly not over large areas, if at all). Unfortunately, most digital map databases used for navigation also do not include the required details.
Well, I don’t like the feeling of being lost, so I take a photo of my surroundings and ask someone to identify the location for me. Hmmm. Who could do that? How could they assign location to my photo? When will this service be available?
Well, I think the answer is Google. We’ll talk about “how” next time. And the “when” question, – whenever they want to roll it out.
Until then, those of you interested in this topic might want to read:
“Landmark-Based Pedestrian Navigation with Enhanced Spatial Reasoning
– Lecture Notes in Computer Science”, Harlan Hile, Radek Grzeszczuk, Alan Liu, Ramakrishna Vedanthan, Jana Kosecka and Gaetano Borriello
Springer Berlin – Heidelberg May 2009. (in H. Tokuda et.al (Eds) Pervasive 2009, LNCS 5538 pp. 59-76 © Springer-Verlag Berlin Heidelberg, 2009) (This is a very interesting article, although curiously, the research was based on Google maps and TeleAtlas data, even though the authors had a connection with the Nokia Research labs. Note: the link to the website mentioned in the article is broken, but if you play with it, you may be able to view their site and examples. I know that sounds vague, but their server seems to work only when it wants to do so.)
“Pedestrian navigation aids: information requirements and design implications,” Andrew J. May, Tracy Ross, Steven H. Bayer and Mikko J. Tarkiainen, published online, Springer-Verlag London Limited 2003.
“Understanding and measuring the urban pervasive infrastructure,” Vassilis Kostakos, Tom Nicolai, Elko Yoneki, Eamonn O’Neill, Holger Kenn and Jon Crowcroft, Personal Ubiquitous Computing (2009) 13:355-364
“How can we best use landmarks to support older people in navigation?”, J. Goodman, S.A. Brewster and P. Gray, in Behaviour and Information Technology, Volume 24, Number 1, January – February 2005, pp. 3-20.