Mobile mapping: challenges and limitations
IMode Phones
The Map services can be delivered to I-Mode phones in more or less similar ways to the WAP model discussed earlier (Fig. 1). The difference being that IMode uses CHTML instead of WML. CHTML is a subset of HTML. Imode is implemented with a packet switched system, which is in principle always on while WAP systems in Europe are at present circuit-switched, i.e. dial-up. Packet switching or circuit switching has a technical difference in the telecommunication system on which the services are based; it has nothing to do in principle with the IMode and WAP standards by itself. In principle, IMode and WAP encoded WebPages can be delivered over packet and circuit switched systems.
PDAs
If the PDAs have a WAP browser installed in them, the information comes in similar fashion as discussed under Wireless phones section above. Some PDAs (Mostly WindowsCE based devices) can access Internet content directly. (Fig 2.) Alternatively, applications running on the PDAs can directly connect to remote servers, retrieve and display information without depending on any browser to display the information. The application running on the PDAs should themselves have interfaces to display the information.
PalmOS Devices
For PDAs like PalmVII – which can’t access Web content (HTML) directly then Web Clipping comes into picture. In such devices PQA (Palm Query Applications) have to be developed on the Palm devices that clip the web-content and receive the bare minimum to display the Map information.
WindowsCE devices
They can connect to the Internet directly as they have in-built soft modems. Thus these devices can directly access Map content from the server, as desktop computers would do.
EPOC devices
These devices can connect to the Internet directly to access Map information. EPOC devices having WAP browsers can have access to the WAP versions of the Map content (Fig. 1). There are other mobile devices like Linux and Embedded Linux devices, Neutrino devices etc. Most of these can connect to the Internet through soft/hard modem and access GIS information.
Land Phones
Having access to information from the Internet without actually connecting to the Internet – One of the ways this is possible is by IVR -Interactive voice response (Ma, 1987). The user who subscribes to the voice service will need to dial a toll free number to get map related information. Software on the server understands the speech and converts that to a text based request to the application server (In our case the map application). Since this facility is available for subscriber only- the voice recognition and demographic recognition software can understand the speech of the user.
Mobile Mapping applications
The mobile applications could deliver the Map Information in different ways such as a) Text: Address and phone of nearest bank, driving direction, Job dispatch operations based on user’s location. b) Image: The path to the service location, on a map. c) Voice: Driving directions, Job dispatch operations. d) Video: Fly-By movies, Traffic congestion Status. There are multifarious applications for Mobile mapping of which the most prominent applications are described below.
Routing applications
Routing could be one of the most popular GIS based solution on mobile terminals. The mobile user could indicate his origin, destination and via locations to the mapping system. Some inputs can also be taken from the GPS device directly. With good transmission speeds (GPRS and higher), the mobile user can also have route guidance (If GPS device is used along with the mobile terminal) on the move. The mobile terminal would get the route result from the server in the form of a detailed way-description- the way description itself can be a text-based display or a voice based directions. The route can be highlighted on the map and shown on the Mobile Terminal. Routing applications can result in the following data being delivered to the Mobile terminal.
Search facility applications
Such location-based applications could search the map database for locations queried according to the preferences given by the user. The user could request information regarding any facility like Hotels, Banks etc around any given location within certain radius. The user’s location itself can be taken from the GPS device if it is attached to the mobile terminal.