Abstract:
Land and water information systems are developed for managing the information such as location,
its limit , characteristic, structure, ownership if available and other relative attributes. For
presenting the geographical locations of the land and water features, map based systems are
being developed. Present day Geographic Information Systems (GIS) are map based systems
which enable the interaction of several map layers for desired output. Most of the available
WebGIS applications for land and water information are limited to selected features, such as
roads, rivers, buildings and forest features. Some are limited to defined Geographical area,
while only primary attribute values are displayed by some other applications. However, with
the increment of requirements for WebGIS application, information and functions are being
enhanced rapidly. When serving large data through a WebGIS application, performance tend
to be slowed. Therefore it is important to identify the issues of WebGIS application in case of
growing databases.
Overall objective of the study is to identify the issues and concerns related to the development
of Web GIS applications for growing databases and then to develop a land and water
information system in order to identify management issues pertaining to the tool development
associated with map serving and combined querying. The specific objectives of the research
are: Identification of WebGIS performance issues with respect to the spatial coverage expansion
and attribute expansion and development of a land and water management WebGIS tool
with user friendly search capability considering possible expansion of coverage.
As very first step, the issues of available web GIS applications are identified by a literature survey.
Meanwhile, a evaluation on development methodology, performance optimization techniques
and performance calculation methods is carried out. The work commenced with the
development ofWebGIS application including information and functionality at basic level. According
to the user survey, the application was enhanced for another three stages with growth
of database and functional operations. The growth rate of database size second stage of the
application is twice than first stage. While third stage growth rate is five times than second
stage and fourth stage having about fifteen times of growth rate of features. The testing process
of each stage was carried out to identify user familiarity, accuracy and performance level of the
application. Performance level was identified by calculating the response time of functions at
each stage.
GeoInfo WebGIS application with better efficiency level of functionalities, user friendly features
and high accuracy level is one of major results of this research. Functionalities ofWebGIS
application are listed as (i) Query for land and water features, their attributes and relative features.
(ii) Map the geographically location of water and land features and (iii) GIS operations
such as location identification, measure length/area, map zoom in/out, pan map and vector and
raster data layers loading. JavaScript, XML, HTML, and PHP are programming languages
for the development of the application, while Postgis is selected as the database.Database to
database functions take high response time of 22.5 seconds in Version 4 while map to database
ii
having the 3.42 seconds as minimum compared with first level ofWebGIS function categories.
When considering all the functions are considered, ”Measure Tool Operation” has the minimum
response time of 0.42 seconds and Maximum is the 59.2 seconds and it is the response
time of ”Displaying list of Buildings” function. A rapid increment of response time is with
functions of fourth versions. Other identified issues are non responsive situations with loading
images, take more time to data loading and map overlaying when browsing and changing .
By evaluating results of the verification process it is identified that database transactions directly
affect the efficiency of functions ofWebGIS application. Reasons for Identified issues of
WebGIS land and water management are (1). Issues with performance of stored procedure (2).
No factor query index (3). Low efficient configuration of server (4).Issues with cache memory
and (5). Trying to load heavy maps and data
Recommendations for WebGIS development are (1).Database to database functions should be
minimize as possible for the best performance of Water and land information management
WebGIS application. (2). When serving the Raster and Polygon data, size should be in small
components as possible. (3).Careful action should be taken when loading more than 10 or 20
records at a given time