Abstract

Surveillance and exchange of gathered information guides emergency response as well as long-term planning. In this paper we have discussed about the Open GIS, which can be very well utilized during different health hazards and in response to that some immediate actions can be taken up based on the available latest information in the said system.

Open Source Web GIS software systems have reached a stage of maturity, sophistication, robustness and stability, and usability and user friendliness rivaling that of commercial, proprietary GIS and Web GIS server products. The Open Source Web GIS community is also actively embracing OGC (Open Geospatial Consortium) standards, including WMS (Web Map Service). WMS enables the creation of Web maps that have layers coming from multiple different remote servers/sources. Here we present one easy to implement Web GIS server solution that is based on the Open Source Map Server. With the help of step-by-step instructions, interested readers running mainstream machines and with no prior technical experience in Web GIS or Internet map servers will be able to publish their own health maps on the Web and add to those maps additional layers retrieved from Remote Wms  servers.

All problems with planning and management are related to location, they are geographically referenced and require spatial analysis and presentation, an Open GIS on any compatible GIS platform will be very helpful tool for planning and decision making in emergency management.

Introduction

All forms of human activity include and involve a measure of geography. Whether you are a restauranteur looking to open up a fast food centre, a geologist seeking a pot of black gold, a stock broker shopping for new investment opportunities, or a suburbanite on a quest for the nearest video store the problems facing you are the age old questions of geography, where, When and how. We all possess a certain understanding of our immediate surroundings, i.e. our neighborhoods and communities through a natural sense of place, however as we increase the scale of our vision to a local, national or international scope our knowledge and therefore our ability to relate things decreases Significantly.

WHAT IS GIS?

Gis is an acronym for:

Geographic

This term is used because GIS tend to deal primarily with `geographic' or `spatial' or 'graphical' features. These objects can be referenced or related to a specific location in space. The objects may be physical, cultural or economic in nature. Features on a map for instance are pictorial representations of spatial objects in the real world. Symbols, colors and line styles are used to represent the different spatial features on the two-dimensional map.

Computer technology has been able to assist in this mapping process through the development of automated cartography (map making) and computer aided design (CAD). Computer programs can now accomplish in minutes and hours tasks, which previously took days or weeks for cartographers and draughtsman to complete.

Information

This represents the large volumes of data, which are usually handled within a GIS. Every graphical object has their particular set of data, which cannot be represented in full details in the map. So all these data have to be associated with corresponding spatial object so that the map can become intelligent. When these data are associated with respective graphical feature these data get turned to information that is now by click of a mouse on any object its corresponding data get highlighted. All information is data but all data are not information.

Systems

This term is used to represent the systems approach taken by GIS, whereby complex environments are broken down into their component parts for ease of understanding and handling but are considered to form an integrated whole. Computer technology has aided and even necessitated this approach so that most information systems are now computer based. Therefore, Geographic Information System (GIS) is a computer based information system used to digitally represent and analyze the geographic features present on the Earth' surface and the events (non-spatial attributes linked to the geography under study) that taking place on it.

Geographical information systems are not restricted to the conventional view of geography i.e. that of people and places on the Earth's surface. Hidden geographies lie everywhere and a GIS is the perfect tool to take with you on voyages of discovery. Whether you are exploring the hidden facets of the World Wide Web, the complex geography of a printed circuit, the architecture of a combat aircraft, or want to know where the high tension transmission lines pass or the intricate layout of the testimony in the Starr report, a GIS will help pave the way for the success of the expedition by providing the means of visualizing and exploring these uncharted territories.

Components of GIS

Hardware

A GIS relies on a computer for storage and processing of data. The size of the computing system will depend on the type and nature of the GIS. A small scale GIS will only need a small personal computer to run on, while a large enterprise wide system with larger computers and a host of client machines to support multiple users. 

Fig. 1: Components of GIS

Software

At a core of any GIS system lies the GIS software itself providing the functionality to store, manage, link, query and analyze geographic data. In addition to the core GIS software various other software components can be added to provide access to additional sources of data and forms of functionality.

Data

Data for a GIS comes in two forms geographic or spatial data, and attribute or a non spatial data. Spatial data are data that contain an explicit geographic location in the form of a set of coordinates. Attribute data are descriptive sets of data that contain various information relevant to a particular location, e.g. depth, height, sales figures, etc. and can be linked to a particular location by means of an identifier, e.g. address, pin code, etc.

Sources of spatial data include paper maps, charts, and drawings scanned or digitized into the system. Digital files imported from CAD or other graphics systems. Coordinate data recorded using a GPS receiver and data captured from satellite imagery or aerial photography.

Methods

GIS systems are designed and developed to aid the data management and decision support processes of an organization. The operation of any organization is based on a set of practices and business logic unique to that organization. While some organizations may use a GIS on an ad-hoc basis with each user formulating their own standards of work and methods of analysis others define their business logic into the GIS to streamline certain aspects of their operations. So the methodology applied is another factor for success of any GIS project.

People

The system users - those who will use the GIS to solve spatial problems - are most often people who are well trained in GIS, perhaps in a specific application of GIS. System operators are responsible for the day-to-day operations of the system, more often performing tasks that allow the system users to function efficiently. GIS suppliers are responsible for providing software support and updates of the software as new and improved methods are put into the system. The Data supplier could be either private or public. The private company may provide internally generated data or data obtained from public agencies modified to better fit needs expressed by the user community. Public agencies, primarily governmental agencies, provide data for large portions of the country. Application developers are generally trained programmers who will provide user interface to reduce the reliance on specialized GIS professionals to perform common tasks. GIS systems analysts are group of people specialize in the study of systems design.

How is data stored in GIS?

§        A GIS stores a representation of the world in the form of layers connected by a common geographical frame of reference.

§        Each of the features on a layer has a unique identifier which distinguishes it from the rest of the features on the layer and allows you to relate it to relevant information stored in external databases, etc

§        This simple yet powerful mode of abstraction, a GIS allows us to capture only those elements of the world that are of interest to us. Different views and data about the world e.g., streets, soils, pipes, cables, vegetation, etc. can be captured and stored in the GIS over time to accommodate the needs of various different users and to reflect changes in the landscape over time.

Fig. 2: Data Storage in GIS

Data models

All graphical features on the earth can be represented by only three identities that are line, point and polygon.

§        The layers of data are stored in the GIS using one of two distinctly different data models, known as raster and vector.

§        In raster model, a feature is defined as a set of cells on a grid. All of the cells on the grid are of the same shape and size and each one is identified by a coordinate location and a value which acts as its identifier, features are represented by a cells or groups of cells that share the same identifier. The raster model is particularly useful for working with continuous forms of features such as soil types, vegetation etc.

§        In vector, a feature is represented as a collection of begin and end points used to define a set of points, lines or polygons which describe the shape and size of the feature. The vector model is particularly useful for representing highly discrete data types such as roads, buildings, boundaries and the like.

§        Vector GIS can store corresponding information of complex objects more efficiently.

Fig. 3: Data Models in GIS

What can one do using GIS?

It's been said that better information leads to better decisions, however in order to get that information you need to be able to ask the right questions, and in order to ask the right questions you need the right set of tools.

Almost all of the questions and issues we are faced with have a geographical component to them. Questions such as where, when, how, why, what if all have an obvious or hidden geographical component. Therefore a GIS with its ability to link and display different data sets on the basis of a common geography appears to be the perfect set of tools for supporting a decision making process, but that's not the end of the story. It is a very well known fact that when we finally succeed in answering one question, a hundred new ones suddenly come to mind, remember maps are food for thought. The real power of a GIS lies in its analytical capabilities to provide simple solutions to complex questions to become a better-informed individual capable of making better decisions.

Query and display

One can start your GIS odyssey using simple queries such as show the states of India in different ranges of literacy rate and he can the see the map (Fig. 4).


Fig. 4: Literacy Map of India

Buffer analysis

This help to answer spatial relationship type of questions like how much area is likely to be submerged in case of any dam burst or how much area can get flooded if the water level of a particular river rises 1m above danger mark. Ex. Show me the villages in my district which have access to a medical facility within 8 km from the village (Fig.5).

Network analysis

Network operators provide a way of solving network and transportation related questions. It is helpful in finding the shortest routes, alternative routes, pollution free routes and so on which are very important in case of accidents, disastersetc.




Fig. 5: Medical facility reaching 8 KM radius (Villages Benefited)

Overlay Analysis and Terrain Modeling

Our forester friend has in some ways has a need to know where the trees are, but logging trees will have an impact on the ground and the landscape, depending on the type of soils and the slope of the land different patterns of soils erosion may take place, which will impact the local water supply in different ways. The forester will have to evaluate his decision on which trees to cut down not having any drastic impact on the environment.


Fig. 6: Digital Elevation Model

Overlay analysis and terrain modeling are methods used by GIS to answer these types of questions by allowing us to look for areas of overlap, e.g. areas where you own a strand of trees that grow on a particular type of soil, or view the terrain assessing the effects of erosion given the slope of the land, or the visual impact clear cutting will have on the landscape.

There are virtually no limits to the scope of GIS analysis by combining any of the modes of analysis and query tools provided by a GIS you can derive answers to the most complex questions posed by any activity or field of study.

OPEN SOURCE AND FREE SOFTWARE
 

What is free software? What about Open Source? Without going too deep into the legal and philosophical issues (a review can be found at: http://www.gnu.org/philosophy/free-sw.html), we can say that a computer program is free when everybody can use, modify, and redistribute it. This implies that the source code of the program must be available, and that usually no license fees are requested. We thus usually refer to these programs as FOSS (Free and Open Source Software). One must be careful to distinguish free programs in the restrictive sense of gratuity; there are many proprietary (closed source) programs that are distributed for free, sometimes as demos or runtimes of larger packages (e.g., in our field, Arc Explorer). The distinction is important, because having access to the source code is essential to guarantee that free software will remain In free forever

In recent years, interest on FOSS has grown considerably, both because of budget choices, and because of the ample scope for customization and reuse; also issues of democracy of information and elimination of the digital divide have a place here. Well-known successes include the dominant position of Apache (http://www.apache.org) among web servers, My SQL (http://www.mysql.com) among web databases, etc.

several elements make FOSS particularly attractive in the developing countries:

§        relatively scarce financial resources, both in the private and in the public sector, push towards the adoption of low-cost solutions

§        the availability of skilled programmers (notably in the case of India, but also in many other countries) able to exploit effectively the scope for customization and further development of existing or new tools

§        resources invested in FOSS development remain in the country, and may help building up a national software industry, whereas money invested in proprietary software (i.e. licenses) goes largely abroad.

Several factors hinder a wider and faster adoption of FOSS in many contexts: freedom implies the availability of a wide variety of products, not all of which are mature and fully functional. It may therefore be difficult, at first sight, to identify the best solutions for a specific application; furthermore, the lack of a solid commercial structure (and the advertisement that come with it) does not help “spreading the word”.

Implementing Web  Gis

Applications using Open Source Software

Internet based geographical data services involve management spatial and non-spatial (attribute) data. Geographic Information System (GIS) has come to be an indispensable tool for analyzing and managing spatial data. Data pertaining to spatial attributes can be efficiently managed using Relational Database Management System (RDBMS). The development of a Web-based system by integrating GIS and RDBMS would serve two crucial purposes. Firstly it would allow the user to operate the system without having to grapple with the underlying intricacies of GIS and RDBMS technology. Secondly, it would allow sharing of information and technical expertise among a wide range of users. In the present paper we describe the salient features of spatial database that was developed by integrating the Open Source Software (OSS) GRASS GIS and Posture SQL Object-Relational database into a Web based client/server environment. The system described in this paper aims at providing a web-based platform for collaboration and data sharing between specialists, planning agencies, citizens, and private entities. In order to access the spatial database, the user need only have a Web browser and access to the Internet. The system can be used to readily build and manage spatial databases pertaining to landslides and is presently being adapted to suit other applications such as a Water Infrastructure Inventory System. Since the system is developed using OSS, it can be easily implemented in a distributed spatial database environment at a low overall cost. In this presentation we discuss salient features of an online system that offers public access to landslide information related to Japan .The basic framework of the system is shown in Figure 7. Further, we also present an overview of our ongoing efforts to improve the interoperability and compliance with the Open GIS Consortium (OGIS) Web Mapping Testbed (Web Mapping Testbed).

Figure 7 Components and Information Flow within the Prototype System

Gis component

GRASS (Geographical Resource Analysis Support System) was used to provide the basic GIS framework. GRASS GIS was originally developed at the United States Army, Construction Engineering Research Laboratory. Presently, the development and distribution is coordinated by the GRASS Development Team (http://www.geog.uni-hannover.de/grass/ index2.html) and is made available under the GNU General Public License (http://www.gnu.org). GRASS is a hybrid vector-raster GIS designed to provide digitizing, image processing, map production, and GIS system capabilities to its user. GRASS contains several routines for importing spatial data of a wide variety of commonly used formats. GRASS files can also be directly imported into many commercially available GIS packages or exported to suitable data formats. The spatial data included in prototype system consists of GRASS raster, vector and site data layers that provide the geographical reference.

RDBMS Component

RDBMS enables the fast storage and retrieval of large amounts of information. The interface that is used to insert, manipulate, and extract data is called the Structured Query Language (SQL). In case of the prototype system, the Postgre SQL database server has been used to manage the attribute data and multi-media content (e.g. image files). Postgre SQL is an Object-Relational DBMS, supporting almost all SQL constructs, including sub-selects, transactions, and user-defined types and functions. The database consists of tables that hold all the available attribute data. The attribute table includes fields that can be used to store binary data (images, multi-media contents etc.). Remote update of the database by permitted users is also made possible. An authentication mechanism to check which users can be allowed to enter new data or update the existing attribute data in the relational database is also provided.

Web component

The system includes of two kinds of web interfaces that enable online access to the GIS layers and attribute information. Access to spatial data (GRASS database) is provided using the GRASS Links interface and PHP (PHP Hypertext Preprocessor) is used as an interface to access the attribute data (PostgreSQL). Since a majority of GRASS commands can be executed in the command mode, it is quite easy to enhance the GRASS Links interface to provide added functionality to the system. In prototype system, several additional features were incorporated into the GIS web-interface to tailor the system for its present requirements. PHP is a server-side scripting language. PHP scripts are included within an HTML document to confer it the capacity of generating web contents on demand. Both GRASSLinks and PHP are distributed under the GNU General Public License and can be deployed on variety hardware platforms. PHP can be used to connect to several database engines such as Postgre SQL,my sql etc.

System features

An online demonstration of the basic features is available at http://gisws.media.osaka -cu.ac.jp/slink/. “Spatial Query” option allows the user to retrieve attribute data from the RDBMS table by selecting a location on the raster image displayed on the web browser. The user selects the GRASS data layers from an interactive menu based on which the GRASS raster layer is displayed on the web-browser. The user can also select vector maps and site data as overlays for raster map layer (Figure 8). Interactive zoom/pan capability allows the user to view the displayed maps in greater details or to choose different areas for display. Once the desired area is displayed on the web-browser, the user is allowed to view the attribute table by “clicking” on respective site. The relation database is queried based on the geographical location (Figure 9a) of the “clicked” site. Attribute data is displayed in two stages. Firstly, a brief summary (Figure 9b) of the attribute information is presented. The summary table also includes a hypertext link, which can be followed to view more detailed information including figures and field photographs is also provided (Figure 10a and 10b).

“Database Search” option allows the user to retrieve attribute information by keyword searching . Search fields include name, location and date. In addition full-text searching is also provided. The results of the text based searching are the same as those shown in Figure 9b and Figure 10.

    
Figure 10 Detailed attribute information on individual landslide. (a-left, b-right)

Conclusion:

For many years, isolated groups  are mastering GIS and working on separate pools of geo-datasets. One was not possibly aware of what the other was working on. However, with the boom of Internet GIS applications,(boom of internet is described as web GIS  in the context of GIS) today everybody can get to know what the others are doing and which data is available with whom. Also, the ultimate beneficiaries of Internet GIS would ultimately be the users or netizens who would explore GIS without the need for investing on GIS tools. For hosting GIS Services on the web, the infrastructure deployment in the form of Web Server, GIS Server, Database Server and other software could be expensive for many organizations. But the astounding growth of Open Source Software provides a much cheaper solution. The apprehension on how one could get solutions and support from open source community no longer exists. The availability of the source code and the right to modify enables the unlimited tuning and improvement of software. The right to redistribute and reuse these modifications and improvements to the code adds to all the advantages to be shared by large communities. A quick look at http://www.freegis.org will surely attract even a novice to take up GIS work

One may think that proprietary software are better at certain times but we have equivalent software which is openly distributed for free .

 As the mobile and internet era is booming GIS development is a great deal for the mankind and for the GIS, usage of open source software for developing products is definitely beneficial and required when we also concern economies of  developing nations .

 To summarize why open source software is ultimate the reasons are

v              Internet and mobile computing are pervasive in nature

v              For internet applications a single monolithic approach controlled by a single vendor is no longer a solution it is a problem

v         for the present world for internet to be a platform the system should be without a owner, tied together by a set of open standardshence requires interoperability

v              Interoperability requires open standards

v              Open standards create a fertile ground for commoditization

v              Open source is good at commodity software

•              html,http->apache http server

•              posix->linux

•              OGC OWS->Mapserver

v              Capacity building: Open source provides a basis for building an IT

Ecosystem in Africa

•              low barrier to entry

•              in south Africa supported by low cost spatial data

hence open source software usage has become an  ultimate tool for building webGIS systems both because of maturity in its software quality and open standard(s) nature it possesses .

References:

[1] http://www.gisdevelopment.net/index.htm

[2] http://www.gis.org

[3] Geoff Zeiss,”open source and Interoperability”, Map Africa, 2006