GIS databases, used by government agencies and private organizations,
must be kept up-to-data to inform decision makers about proper management
of resources (Alesheikh and Fard, 2007; Longley et al., 2005).
Data gathering is a time and money consuming task (Hosseinali and Alesheikh,
2008). The recent evolutions in Mobile GIS caused the possibility to cost
effectively gather and manage GIS data (Amirian and Alesheikh, 2008a).
Mobile GIS is the accessing, using and storing of geospatial data directly
in the field. Mobile GIS addresses the needs not only of GIS managers,
but also, of field inspectors, maintenance teams, utility crews, emergency
repair workers and other field workers who need timely access to GIS data
in the field (McLarin, 2004).
Mobile GIS is evolved with developments in:
||Global positioning system (GPS) technology
||Rugged handheld computing technologies
||Wireless communications and
||GIS software for mobile platforms
Mobile GIS depends heavily on high quality data in the GIS database.
However, in many organizations this data can be obsolete or even non-existent.
GIS data collection is the process of populating a GIS with data on the
properties, including position and attribute information, of interest
to the organization.
Until recently, collecting and using information in the field was a paper-based
process with multiple points of data entry without accessing to real-time
information or the ability to accurately communicate field observations
back to the central stations. The recent developments in mobile GIS technologies
have benefited many field-based information gathering. Information collection
can now be performed more accurately with higher efficiency (ESRI.com,
Mobile GIS can facilitate the following field processes:
||Asset inventory-recording the location and attribute
information of an asset on a digital map
||Asset maintenance-managing asset location, condition and maintenance
schedules in the field
||Inspections-maintaining digital records of field assets for legal
||Incident reporting-spatially recording accidents or events
The process of decoding field notes, entering valid information into
the geodatabase and redistributing new study maps is time-consuming, expensive
and at risk for errors. However, what is routine and necessary is to maintain
geodatabases (Wilke, 2003). Mobile GIS has made it possible to digitally
view and edit spatial data in the field. It overcomes the shortcomings
of study maps and provides real benefits to field-workers as well as cost
benefits for the utility.
A GPS data collection system has the same basic components as a Mobile
GIS system. It requires the user to locate and then record position and
attribute information about the features of interest. GPS technology provides
the obvious choice for recording reliable position information, while,
handheld computer platforms running field-optimized software allow the
user to efficiently record feature and attribute data (McLarin, 2004).
During the past years, tremendous advances have taken place in GPS technology
(receivers), data collection hardware and field data collection software.
Not only has the autonomous GPS accuracy improved, but the data collectors
have become smaller, lighter and less expensive. The software has become
cheaper and easier to learn (Wadhwani, 2001).
With the introduction of Palm Pilots followed by Microsoft`s launch of
a pocket PC operating system, a new generation of handheld Personal Digital
Assistants (PDA`s) have swamped the market. It is now possible to use
these lightweight handheld PDA`s, with GPS/GIS data collection software,
for field applications.
Onboard digital cameras allow users to include a visual record as part
of the field data collection process. An application can automatically
control the camera, preview an image and finally take a proper photo for
possible inspections. The photo can then be linked to its real world location
where it was taken and associated with descriptive attribute information.
In this study a system is developed to assist operators in data collection
for electrical power industries.
MOBILE GIS ARCHITECTURES
Mobile GIS is based on mobile computing and mobile Internet. It is an
extension of Web GIS to mobile Internet including wireless Internet/Intranet
and mobile communication network (Fangxiong and Zhiyong, 2004). Mobile
GIS have several restrictions due to the limited capabilities of both
hand-held hardware and the network data transfer speeds and bandwidth
(Drummond et al., 2006). The diversity of mobile devices, the limitation
in processing power and screen display and the diversity of mobile system
platforms are examples of hand-held challenges. Various architectures
have been proposed for mobile GIS implementation, namely; Stand-Alone,
Client-Server, Distributed, Services and Peer-to-peer (Bryan, 2001).
|| The stand-alone client architecture
|| The client-server architecture
The simplest Mobile GIS architecture is the stand-alone client. In this
architecture the application and spatial data reside entirely on the mobile
device (Fig. 1). Although, some applications may profit
from this approach, such settings have major drawbacks. First, the hardware
resources of the mobile device restrict the amount of spatial data the
application can support. Second, this architecture does not allow for
communication with any other applications.
To address the above challenges, client-server architecture can be adopted.
As Fig. 2 presents, spatial data is moved to a separate
computer and served to the client by GIS server software. The GIS applications
can still be in the mobile device searching for data in data servers.
Depending on the GIS applications, the location of the servers and the
network constraints, thin, thick or medium clients may be adopted (Alesheikh
and Helali, 2002). In such architecture, the spatial data is constrained
by the resources of an enterprise server. Moreover, multiple mobile devices
running the same application can access the server concurrently, making
this a potentially multi-user architecture. However, the architecture
poses a new constraint: Communication. If the mobile cannot establish
communication to the data server, the GIS applications are useless and
the architecture losses its versatility. Due to range and interferences,
inconsistent communication occurs frequently in mobile applications.
In order to overcome the inconsistent connectivity, two challenges must
be addressed: Persistence and resource management.
|| The distributed client-server architecture
|| The services architecture
|| The peer-to-peer architecture
A distributed framework
can handle the logic for persistence and resource management (Fig.
To further extend the back-end functionality of mobile GIS, applications
can view the GIS server as a web service and allow for other web services
to be part of the application (Fig. 4). Since the web
services use similar communications protocol, all mobile devices can communicate
with each other. In addition, the web services can also communicate between
themselves using SOAP XML, the industry standard for passing messages
between software components (Alesheikh et al., 2005). Once employed,
this architecture can support robust communication between any number
of mobile devices and web services. Unfortunately, it might not be the
best for some applications, such as those designed for collaboration in
remote areas where connectivity to servers is unavailable.
In a peer-to-peer architecture a server is no longer available to keep
spatial data; the data must be stored on the mobile devices themselves
as seen in Fig. 5. However, if each mobile device stores
100% of the data, then the architecture is restricted in the same manner
as the Stand-Alone Client.
To allow for more data storage throughout the application, each mobile
device keeps just a subset of the data. When Mobile Device A needs data,
it relies on its distributed framework`s resource management to know if
it has that data locally. If it does not, the distributed framework must
know how to access that data on Mobile Device B (Kalantari et al.,
MOBILE GIS COMPONENTS
The core components of a mobile GIS are the same as generic mobile business
systems. A mobile GIS has three fundamental components: Hardware, software
and the wireless network, which connects the mobile device to a data repository.
The hardware component consists of the mobile device; a suitably configured
wireless modem; a Web Server with wireless support, i.e., a wap gateway,
a communications server and/or a mobile communications server switch so
that the mobile device can communicate with the internet or an intranet
and an application or database server that contains the application`s
logic and databases (Amirian and Alesheikh, 2008b).
The software component includes the mobile device operating system (Windows
98/2000/NT, PalmOS, Win CE, EPOC, etc.); the mobile application user interface,
which may run through an Internet browser; application server and/or database
server software; application middleware if the mobile device needs to
communicate with legacy (predecessor) systems or web-based application
servers and wireless middleware that links multiple types of wireless
networks to application servers (Malek et al., 2007).
The wireless network component may be either a private network such as
that used by law enforcement or emergency services or a public shared
network. Connectivity to wired networks or wireless LANs may also be included
depending on the requirements of the mobile application.
Since many organizations` activities are based on spatial information,
collecting spatial data has become outstandingly as one of the organizations
target. Electricity Transmission and Distribution companies are among
the companies that require spatial data and need a spatial information
system with an up-to-date database of the conditions of the transmission
lines, distribution lines, posts and other spatial features. By considering
the importance and the role of a spatial information system in the electrical
industry (production, outfitting and maintenance parts), a system for
collecting spatial data related to transmission and distribution posts
was designed. A user-friendly system was developed to enable operators
to gather and save descriptive information, the feature`s position by
GPS and the feature`s picture. The system is designed to work off-line
(Stand-Alone Client Architecture) as well as online (Distributed Architecture).
In this project a HP iPAQ hw 6945 was used to collect data. The device
was equipped with an internal GPS receiver and a 1.3 mega pixel camera.
The device has also the features of a cell phone in addition to the ability
to communicate via infrared, Bluetooth and Wi-Fi technology. The mobile
is integrated with a high sensitivity GPS receiver and HP iPAQ Quick GPS
Connection technology. Quick GPS Connection technology is a software application
residing on the device that enables a faster connection for enhanced GPS
The operating system of the device is Windows Mobile and has the ability
of programming (Application programming) using .Net technology. The system`s
software is consisted of two parts: The database and the user interface.
The needed information contents for collecting geodata were extracted
from the related data models and the database was designed in SQL Server
CE (Compact Edition).
The user interface was designed based on .Net compact framework using
Window Mobile APIs. A connection between the program and the database
was established and the program was setup for use in Pocket PC.
By using the designed software the ability to insert, edit and search
information, to register the position and the picture of the feature is
provided; in such a manner that the information will be saved in the database
and its` transmission and retrieval in the central database will be easily
done. Figure 6 presents the several user interfaces
for data entry and capturing photos.
The system has been set up for practical uses in Tehran Regional Power
Company. The initial results are promising as it populates the database
in real time. The deployed system has several practical features. The
most compelling are:
||Access to data in the field (where, it is often needed
||Capture data in the field and in real-time (it includes photos)
||Append positional information to data capture
||Run GIS functionality in the field, (where, again it is often needed
Further, GIS applications are requested to guide the maintenance crew
to the needed utilities locations.
|| The user interfaces of the developed system
Both the hardware and software available for digital data acquisition
have advanced considerably in recent years. Professional clients look
towards mobile platforms to increase productivity through efficient information
handling, resulting In cost reduction, as well as a well-informed mobile
This study analyzed mobile GIS architectures and its components. The study
also presented a mobile GIS for power industry users. The ability of the system
to capture positional data through its GPS receiver, gather descriptive information
using its API and take photo made the system cost effective.
With mobile GIS, data is always in a digital format, making it easy and
efficient to transfer from the field to the office without introducing
interpretive errors. Checks and balances are still required, of course,
but many of these can be automated so, those carrying out the checks can
focus on the real errors.