The term geoinformatics consists of two words, geo (Earth) and informatics (the study of information processing). Hence, geoinformatics can be understood as the union of Earth sciences and Informatics. We can say that Geoinformatics broadly deals with the use of information technology for collection, analysis, storage, retrieval, representation and dissemination of information about the Earth.
Geoinformatics is an integrated spatial research tool. It encompasses a broad range of disciplines including surveying and mapping, Remote Sensing, Geographic Information Systems (GIS), Global Positioning System (GPS), Geodesy and computer science. Various components of geoinformatics are the followings:
Informatics, as a discipline, comprises of both the computer technologies, i.e. hardware and software. The important role of information derives from our necessity to manage more and more numerous and complex data in every field. The knowledge of computer science is a pre-requisite to represent and process applicable information through the development of hardware and software. Computer science culture is now more prevalent contributing in improvement of our activities and research. The application and usage of computer science to geoinformatics go hand-in-hand. You will come across various aspects of the application of computer science to geoinformatics while studying about geoinformatics data acquisition, processing, product generation, data visualisation, dissemination, etc.
Geodesy also known as geodeticsis the discipline that deals with the measurement and representation of the Earth. Geodesyis defined as the science concerned with the study of shape and area of the Earth. Geodesy defines the shape and dimensions of the Earth through its two branches: gravimetry and positioning astronomy.
Gravimetry deals with the determination of Earth’s gravity and its anomalies and the gravity determines the shape of the Earth.
Positioning astronomy determines the position of the points on the globe through the observation of stars and artificial satellites.
The study of geodesy began with mere curiosity and the never-ending human inquisitiveness to explain the Earth’s unknown through logic. It has been a great challenge for researchers to accurately represent the 3-dimensional Earth into 2-dimensional map forms. The underlying concept of geodesy helps in representing the Earth in 2-dimensions.
Cartography is generally considered to be the science and art of designing, constructing and producing maps. It includes almost every operation from original field work to final printing and marketing of maps. It is also treated as a science of human communication. International Cartographic Association defines Cartography as the discipline dealing with the conception, production, dissemination and study of maps. Map is a drawing of the whole or part of the surface of the Earth on a plane surface to a particular scale. It is a manually or mechanically drawn picture of the Earth showing the location and distribution of various natural and cultural phenomena.
Cartographic representation is the key in deciding the fate of any map generated out of various geoinformatics analysis. Cartographic visualisation, which is the graphical presentation of geographic information, such as data, processes, relations or concepts, limits the extent of map details which could be incorporated for any given study area.
Photogrammetry is the technology developed for determining the geometric properties of objects from their photographic images. Photogrammetry is concerned with making measurements about position and shape of objects with the help of photographs. The American Society for Photogrammetry and Remote Sensing (ASPRS) has defined photogrammetry as “…the art, science, and technology of obtaining reliable information about physical objects and the environment through processes of recording, measuring and interpreting photographic images and patterns of recorded radiant electromagnetic energy and other phenomena”.
Photogrammetry is useful in various fields including topographic mapping, architecture, engineering, manufacturing, quality control, police investigation, and geology. Archaeologists use photogrammetry to produce plans of large or complex sites. Meteorologists use it to determine the actual wind speed of a tornado in places where objective weather data cannot be obtained. In movie production, photogrammetry is used to combine live action with computer generated imagery.
Remote sensingis the collection of data about an object from a distance.
Scientists use the technique of remote sensing to monitor or measure phenomena found in the Earth’s lithosphere, biosphere, hydrosphere, and atmosphere. Humans and many other types of animals accomplish this task with aid of eyes or by the sense of smell or hearing. Remote sensing is usually done with the help of mechanical device known as remote sensor. This device has greatly improved ability to receive and record information about an object without having any physical contact with them. Often, these sensors are positioned away from the object of interest by using helicopters, planes, and satellites. Most remote sensing devices record information about an object by measuring an object’s transmission of electromagnetic energy from reflecting and radiating surfaces.
The simplest form of remote sensing uses photographic cameras to record information from visible or near infrared wavelengths of the electromagnetic spectrum.
When the energy (in the form of electromagnetic radiation) reaches the Earth’s atmosphere, it undergoes the process of reflection, absorption and transmission. Earth’s surface consists of different natural and man-made features which reflect, absorb, store and emit Earth’s radiation at different wavelengths in different percentages, depending upon their physical and chemical properties.
Remote sensing sensors record different amount of radiation that is reflected or emitted from different earth surface features and reproduce it in form of an image. Remote sensing provides synoptic view of the earth surface by virtue of recording interactions of Earth surface features with electromagnetic radiation. These interactions are recorded in remote sensing images in the form of some numerical information. When the remote sensing data is generated employing Sun’s energy it is known as passive remote sensing. In the other type i.e. active remote sensing, remote sensors, such as radars, send radiation themselves and collect the signal returned back to them from Earth surface features. Based on the factors, such as portion of the electromagnetic spectrum used and the number of bands, sensors are generally categorised into optical and microwave:
Optical sensors: These operate in the region between 0.3 and 15 μm of the electromagnetic spectrum.
Microwave sensors: These operate in the microwave region of the electromagnetic spectrum (EMS). Optical remote sensing is further classified as panchromatic RS, multispectral RS, superspectral RS, hyperspectral RS and thermal RS. We will discuss about them in the next unit.
Remote sensing imagery has many applications in mapping land-use and land cover, agriculture, soil mapping, forestry, city planning, archaeological investigations, military observation, and geomorphological surveying, mineral exploration, among other uses. One of the common examples of the use of remote sensing is the weather maps which you see in the news channels providing forecast of weather conditions.
More recently, laser scanning systems have come up which have the ability to produce complete information with high precision and automation. Remote sensing has following advantages over other forms of data collection methods:
Global Positioning System (GPS) is a constellation of about 24 satellites which are orbiting the Earth every 12 hours at an altitude of ~20,200 km. These satellites broadcast signals, which are used to derive precise timing, location, and velocity information. The derived information can then be clubbed with other systems, such as communication devices, computers, and software to perform a variety of functions. With equipment ranging from hand-held receivers to rack-mounted electronics, the signals of GPS can be used by anyone, anytime, anywhere in the world. GPS technology consisting of space, control and user segments enables people to precisely know where they are on the surface of the Earth. Prior to GPS, positions were being established by complex procedure of relative and absolute measurements of directions and distances.
Real world applications of GPS fall into following five broad categories:
One of the applications of GPS gaining momentum is the Location Based Services (LBS). LBS are geoinformation services that can provide location aware information based on the user’s current position. LBS are primarily used in emergency services. However, these are also used to provide information on nearby public resources (such as fuel stations, bus stops, ATM machines, etc.), for map and navigation services (such as in vehicles), and even for locating friends though your mobiles.
GAGAN (GPS Aided Geo Augmented Navigation or GPS and Geo Augmented Navigation system) is a planned implementation of a regional Satellite Based Augmentation System (SBAS) by the Indian government. The project is being implemented by the Airport Authority of India with the help of the Indian Space Research Organisation’s (ISRO) technology and space support. Its aim is to provide navigation system for all phases of flight over the Indian airspace and in the adjoining area.
Geographic Information System (GIS)integrates hardware, software, and data for capturing, managing, analysing, and displaying all forms of geographically referenced information. GIShas been defined based on its different aspects i.e.the tools, the organisation and the spatial database. GIS allows us to view, understand, question, interpret, and visualise data in many ways that reveal relationships, patterns, and trends in the form of maps, globes, reports, and charts. A GIS helps you answer questions and solve problems by looking at your data in a way that is quickly understood and easily shared.
The components of GIS include: the computer systems, the software, spatial data, data management and analysis procedures, and the people to operate the GIS. Data forms the major component of GIS. With recent developments in remote sensing and GPS technologies, large volume of high-resolution data is widely available at affordable cost. The remote sensing data and GPS data are used as input in GIS. Computer hardware and software components are required for data entry, data storage, data processing, and analysis and also for producing outputs. GIS is of no use if people and the organisations in which they work are not properly oriented towards GIS.
Finally, the information generated in GIS is communicated through network. GIS has been traditionally used as a tool for generating outputs helping in decision making process for urban planning, management of natural resources, natural hazard assessment and management, environmental management and many more. Recently, GIS has been used for emergency planning, logistics and transportation related analysis, crime analysis, business and service planning, government and public services, analysis of genome sequences on DNA, etc. Internet has also been exploited to disseminate geographic information to the general public resulting into a new breed of specialised GIS generally known as Web GIS.
