The term satellite refers to any object orbiting a larger one, thus Earth’s moon and all the oter moons of the solar system are satellites. Satellites may be natural or artificial. Artificial satellites are often launched by entities including national government, international Association and independent firms. They are planted in the orbit for the purpose of information gathering and dissemination.
This refers to the small or large scale acquisition of information of an object or phenomena by the use of either recording or real time sensing devices that are wireless or not in physical or intimate contact with the object (such as by way of aircraft, spacecraft, satellite, buoy or ship). Currently, remote sensing refers to the use of imagery sensor technologies including instruments found in aircrafts and spacecrafts as well as those used in electrophysiology.
It involves the viewing of objects from the air or from space by utilizing electromagnetic radiations across a wide spectrum. It is restricted to the use of techniques involving radiation on the electromagnetic spectrum. This includes visible infra-red and ultra-violet light as well as low frequency signals in the microwave of range of the spectrum.
Applications of Satellite Remote Sensing
Remote sensing is used for a variety of purposes. The application of remote sensing goes beyond cartography (map making) and measurement.
- It is used in collecting data from places which are impossible for people to penetrate, such as forests.
- Aerial or satellite photography is used for providing measurement of distance between objects on the ground from above.
- Air photography is used for surveillance purposes by the military.
- It is useful in identifying disaster spots or potential disasters.
- It is used by agriculturalists to detect or monitor the spread of pests and diseases in farmlands.
- It is useful in monitoring urban growth and development. It is a useful tool for analyzing land patterns of cities.
- It is a useful tool for measuring and mapping vegetational changes that is widely used in forestry, environmental and agricultural studies.
Relationship between GIS Remote Sensing
Geographic information System (GIS) and remote sensing are integrated. Remote sensing processes obtain data from remote places including space which cannot be easily accessed or seen by man. It is the GIS that extracts and separates the array of information from the satellite imagery into the different geographic features that can be analysed for decision making. The GIS also gives the geographic features extracted from remote sensing geographical attributes, that is, locational and geometric characteristics.
The relationship between remote sensing and GIS can be state as follows:
- Remote sensing provides data that is processed and used in GIS for decision making
- The data from remote sensing and aerial photographs, are often manipulated and analysed for interpretation in GIS.
- GIS does not generate data, rather it utilizes data generated from remote sensing, satellite imagery, aerial photographs, land surveys, etc. the GIS merly stores, retrieves and transfers to other medium.
Application of GIS
GIS provides locational information which is useful to a number of professionals, including planners, policy makers and public administrators. The data generated from the operations of GIS is useful in the promotion of sustainable development of resources and solving of real life problems.
The usefulness and application of GIS can be outlined as follows:
- It is used in handling and managing spatial data and their associated non-spatial aspects.
The major spatial data handling applications of GIS include:
- Data capture (input)
- Data storage, retrieval, verification checking/editing, Ad-hoc query, analysis, manipulation, integration, managing, data modeling, conversion, display and graphics and non-graphic output .
- It is used in performing some cartographic tasks. The cartographic and engineering application of GIS are topographic database, thematic mapping, boundary delimitation and adjustment, map-updating, map rescaling, transformation of maps, map projections, map generalization, lettering, colour separation, atlas production, engineering designs/drafting, assessing the amount of surface infilling or leveling to be done during construction works, map data handling and models stimulation.
- It is used in land and property management. Accurate and up-to-date cadastral map are produced using GIS. A good example is the Abuja Geographical Information System (AGIS).
Maps produced from GIS often have appropriate scales and are useful in a number of ways including, description, registration and sales of lands, generation of revenue, planning and administration as well as engineering work. Generally, GIS application to land and property management include:
- Maintenance of land property records.
- Land/property taxation.
- Property (tenement) rate administration
- Land/property acquisition of disposal
- Processing/issuing of permits
- Monitoring land/property development
- Zoning/subdivisionof land use and Enforcement of zoning bye-laws.
- Production/updating of land property maps.
- Reviewing/approving site plans and conducting title searches.
- Responding to public
- Housing allocation and assessment of housing quality.
- It is used in studying transportation problems relating to traffic congestion, optimum location of transport facilities, network, analysis, transport systems, modeling and analysis of transport induced environmental problems, etc.
GIS application to transportation management include naming of streets, house numbering, street network analysis, managing mailing lists, vehicle routing and scheduling, traffic congestion analysis and control, development of evacuation plans, address matching, highway and other routes planning and design, monitoring and maintenance of road condition, road mapping, accident analysis, transport facilities inventory and management, assessment of environment impact of transportation, air traffic control, sitting of terminals egg bus stops, motor parks, railway station and inland water ports, etc. Others includes planning and management of inland water ways, production of navigational biometric charts, airport facilities mapping, monitoring and maintenance.
- GIS in combination with remote sensing systems is used in providing timely and quality information that helps agricultural policy makers in making sound management decision in the following areas, inventory and mapping of agricultural biodiversity, spatial analysis and measurement of agro-related variables, provision of field specific condition information of precise agricultural farming, mapping of crop pattern, provision of accurate, relevant and timely information for effective agro-extension services, identifying the presence of pest and herbicides, planning and implication of mitigation measures, agricultural land evolution and classification, assessment of environmental impacts/existing agro-projects or the likely impacts of the proposed ones, mapping soil characteristics, site selection for locating agricultural projects and infrastructural facilities, delineation of agro-climate ecological zones, valuation of agricultural land and soil suitability analyses. Others are crop identification and delineating crop soil relations, estimating crop yield, monitoring of crop health and growth conditions, inventory of crops and livestock, management of grazing fields, mapping irrigated arrow and identifying poorly irrigated areas, etc.
- GIS is a forest management tool which enhances various management practices, including
- Mapping of forest resources.
- Identifying factors responsible for a change in vegetation cover
- Conservation/protection of endangered species.
- Scheduling timber harvest.
- Maintenance of up to date inventory of forest resources.
- Monitoring and assessing forest change.
- Estimating timber value.
- Monitoring the growth and health of forest resources.
- Planning and modeling route, location and construction of roads/paths.
- Planning afforestation and reforestation programmes.
- Deference and National Emergency
GIS technology is essential in modern military operations.
- Terrain model planning of the movement of personal and vehicles.
- Site selection for the location of military installation.
- Inventory and tracking of facilities
- Intelligent data gathering and integration
- Target site identification and launch of attack.
- Tactical support planning
- Mapping and analysis of spatial pattern of crime
- Events mapping
- Definition of public patrol routes and zones.
- Planning and identification of emergency execution routes.
- Determining the possibility of a new and anticipated immense natural disaster.
- Natural hazard monitory
- Design and development of emergency and safety plans.
- Selection of suitable sites for relocating evacuees.
- Provision of early warning information about an impending disaster, etc.
- Census: GIS, cartography and remote sensing are of vital importance to pre and post census activities. GIS provides some excellent tools for effective handling of census. It helps to sift the census data for relevant information. It is also used to translate census data to analytical maps, tables and charts. Some of the possible areas of GIS application to census activities include:
- Assessment of total work load
- Estimation of the amount of human and material resources needed for a survey.
- Delineation of enumeration areas.
- Distribution of enumerators and supervisors/materials
- Census data based management
- Spatial and aspatial census data query and retrieval.
- Integration of spatial over log of census data and some other relevant geo-referenced data layers.
- Geo-statistical analysis of demographic variables
- 3-D modeling of census results.
- Production of thematic maps of census variable
- Publication of population data
- Up-dating of census data.
- Inter-censual pop estimation
- The application of GIS in health and environmental management is very pronounced all over the world in the following areas.
- Mapping of disease location and spread
- Location of health facilities
- Public health planning
- Health services delivery
- Planning/monitoring sanitation/inspection
- Mapping of ecological disaster, as for example, soil erosion, flooding, land slide, bush fires.
- Mapping and assessment of spatial and temporal distribution of epidemiology.
- Mapping and analysis of access to health care providers and facilities, etc.
- Hazardous (toxic) facility siting
- Solid waste management disposal sites (dump sites)
- Mapping water pollution/air pollution
- Assessment of environmental quality/impact assessment
- Environmental auditing and formulation of environmental regulations and policies.
- Environmental modeling
Problems with GIS Interpretation in Nigeria
Geographic information system as a discipline is quite recent in Nigeria and as such is confronted with many problems. The main problem facing GIS interpretations in Nigeria are:
- Power supply
- Insufficient capital
- Power supply: GIS is totally dependent on electricity supply for its full operation and management. However, electricity supply is quite unsteady.
The power supplied by the Power-Holding Company (PHCN) is unreliable. It is characterized with incessant blackouts which last for long periods. This situation hinders the effective development of GIS in Nigeria. A few organizations that operate GIS rely on private generators which are expensive to maintain.
- Insufficient Personnel: The personnel needs to engineer the GIS hard ware and software components, and make useful decisions based on the available information, can sometimes be insufficient in Nigeria.
The absence or shortage of persons with sufficient technological knowledge in GIS has affected the successful implementation of GIS. A great number of the Nigerian population are not computer literate. Nigeria still has very few computer engineers, GIS technicians, GIS data provides, GIS scientists, etc. Nigeria still relies on foreign exports for the successful implementation of GIS.
- Insufficient Capital: acquisition of GIS components including, computer hardware’s and software is capital intensive. However, Nigeria does not have sufficient capital to embark on large scale GIS development. Only very few organizations and government institutions have acquired GIS equipment. The country does not have enough capital to embark on the training and re-training of people and the provision of GIS facilities to boost GIS implementation.
- The GIS data which exist in primary or secondary form may not be internationally acceptable. Some existing data are not geo-referenced (space related). Others may be in analogue format, whereas contemporary data are in digital form. Some data are obsolete and may not appear in the correct scale. The absence of appropriate data hinders the interpretation of GIS in Nigeria.
- Absence of National Policy on Computer Education: Until recently, computer education was not made compulsory in schools. Only few secondary schools are now offering computer education.
The absence of National policy on computer education has a negative effect on the development and promotion of GIS implementation.
The Prospects of GIS in Nigeria
Geographic information systems development has bright prospects in Nigeria. The revolution is gathering momentum and more people are acquiring skills in the new technology. In addition, many tertiary institutions are establishing GIS units and training students in GIS. GIS is being offered as a course/discipline at post graduate level.
In contemporary Nigeria, GIS experts are being employed in government departments and agencies. Experts in GIS are highly needed in town planning, estate management agricultural firms, civil engineering, and Military establishment. etc.
The on-going manpower development programme in GIS, the high demand for GIS experts and the diverse areas demanding GIS specialists are indications that bright prospects of Geographic information Systems in Nigeria.
It should however be noted that the rate at which GIS personnel’s are being turned out by many universities in Nigeria is still low. GIS is not even offered as a course by many departments in geography of some universities.