by Chioma Innocent | Wed Dec, 2022 | Geospatial data, Remote Sensing, Satellite |
Techniques of Remote Sensing.
Remote sensing is detecting and monitoring an area’s physical characteristics by measuring its reflected and emitted radiation at a distance. The earth is scanned by satellites or high-flying aircraft in order to obtain information about it.
Two main types of remote sensing exist and are classified according to the source of signal they use to explore the object, active and passive.
Active remote sensing instruments operate with their own source of emission or light.
Passive remote sensing relies on the reflected emission to obtain information. Reflected sunlight is the most common source of radiation measured by passive sensors.
Passive sensors can only detect energy when naturally occurring energy is available. For all reflected energy, this can only take place during the time when the sun is illuminating the Earth. There is no reflected energy available from the sun at night. The energy that is naturally emitted (such as thermal infrared) can be detected day or night, as long as the energy is large enough to be recorded.
Active sensors, on the other hand, provide their own energy source for illumination. The sensor emits radiation which is directed toward the target to be investigated. The radiation reflected from that target is detected and measured by the sensor.
The advantages of active sensors include the ability to obtain measurements anytime, regardless of the time of day or season. Active sensors can be used for examining wavelengths that are not sufficiently provided by the sun, such as microwaves, or to better control the way a target is illuminated.
However, active systems require the generation of a relatively large amount of energy to illuminate targets adequately.
The sun provides a very convenient source of energy for remote sensing. The sun’s energy is either reflected, as it is for visible wavelengths, or absorbed and then re-emitted, as it is for thermal infrared wavelengths. Remote sensing systems which measure the energy that is naturally available are called passive sensors.
A random/common example is using a camera in sunlight. During a bright sunny day, enough sunlight illuminates the targets and then reflects toward the camera lens. The camera records the radiation provided. This can be described as remote sensing in passive mode.
On a cloudy day or inside a room, there is often not enough sunlight for the camera to record the targets adequately. So, it uses its own energy source – a flash – to illuminate the targets and record the radiation reflected from them. This can be described as an active mode of remote sensing.
by Chioma Innocent | Wed Nov, 2022 | GIS Application and Training, Remote Sensing |
Remote sensing and the environment
Remote Sensing is the process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance (typically from satellite or aircraft). Special cameras collect remotely sensed images, which help researchers “sense” things about the Earth.
The use of remote sensing (RS) makes it possible to provide reliable information on environmental conditions, properties of the spatial structure of natural-territorial complexes, their dynamics and helps in accumulation of data for the development of the system natural resources monitoring.
By utilizing GIS modeling tools, potential impacts can be predicted and included in the management and monitoring programs. GIS and remote sensing could be used in environmental monitoring for Land use / Land cover analysis, wetland assessment and ground water modeling, habitat mapping, disaster management etc.
Remote Sensing replaces slower, costly data collection on the ground, providing fast and repetitive coverage of extremely large areas for everyday applications, ranging from weather forecasts to reports on natural disasters or climate change.
The applications of remote sensing include land-use mapping, weather forecasting, environmental study, natural hazards study, and resource exploration.
- The information derived from remote sensing can be directly related to measuring important socio-economic impacts. Rates of land cover change and drought, for example, will strongly influence vegetation yield, which substantially impact upon human health and well-being.
- It helps to create information base on land use, land cover distribution, urban change detection, monitoring urban growth and urban environmental impact assessment. Satellite images enable us to better understand some of the intrinsic components of urban ecosystems and the interactions within whole urban environment.
- Most of the information used by soil scientists to map soil seriesis obtained by direct observation in the field. It is essential that subsurface soil profiles be examined and careful biological, chemical, and physical measurements be obtained within each soil horizon.
Larger areas can be sensed remotely in a very easy way and the whole data can be easily processed and analysed fast by using the computer and that data is utilised for various purposes. Data Collection is really very easy over a variety of scales and solutions.
by Chioma Innocent | Mon Nov, 2022 | GIS and Remote Sensing, GIS Application and Training, GIS Events |
Geographic Information Systems GIS is a tool mainly used to gather, analyse, and interpret data captured during the remote sensing process.
It is applicable in different sectors where it is used by professional analysts to analyse data for different uses.
Housing is one of the basic needs of humans along with food and water. A good shelter should protect the person in it from unfavourable weather conditions all year round.
Apart from natural disasters which occur occasionally, shelters should be able to withstand most conditions.
Even in cases of natural disasters, GIS has been known to help rescue efforts and help detect the best place to settle to prevent reoccurrences.
One of the main applications of GIS use in the housing sector has been in the area of dealing with environmental hazards such as floods, landslides, soil erosion, and drought. It is not possible to stop these events but GIS can be used to mitigate or decrease their impact
- GIS aids effective land administration, providing the platform for structured housing and land management.
- GIS can help individuals and businesses protect property rights, encourage open and competitive real estate markets, bring efficiencies in land administration (SDI, government, taxation, land consolidation etc)
- GIS aids in Land Use Classification and planning.
- GIS aids in the creation and management of Creation of address registers in partnership with local government areas, for easy analysis and upgrade of community database and mapping.
- Besides mapping areas in real estate, GIS can also play an important role in spatial analysis and determination of the absolute location where houses need to be situated.
- GIS Makes Performing Market Analysis Better: Market analysis is one of the most essential steps in housing. Research needed for each may differ in depth, but both require analyzing comparative sales in a given location. Prior to analysis, additional research is conducted on comparable properties recently developed in the subject property’s area.
- GIS enables tasks including site selection, land suitability analysis, land use and transport modelling, the identification of planning action areas, and impact assessments.
by Chioma Innocent | Mon Jul, 2022 | Geoinfotech Blog, Geospatial technology, Service, Tips and Tricks |
7 WAYS GEOSPATIAL DATA HELPED DURING THE OUTBREAK OF COVID-19
Geospatial Data Helped During Covid-19
Geographic information science (GIS) has been established as a distinct domain and is incredibly useful whenever the research is related to geography, space, and other spatial dimensions.
However, the scientific landscape on the integration of GIS in COVID-related studies is largely unknown. Let us assess the implementation of GIS and other geospatial tools during the outbreak of the Covid-19 pandemic.
COVID-19 is part of the coronavirus family that causes a range of familiar diseases from the common cold to SARS. Covid-19 is referred to as a novel coronavirus because it is new to humans. It is transmitted through the air with high risk in proximity.
The main advantage of GIS is mapping the many different locations of treatment and isolation facilities which helps in better monitoring and surveillance of the disease.
GIS was also employed to:
- Forecast the disease
- Predict areas where outbreaks were likely to occur
- Identify disease cluster or hotspot
- Evaluate different strategies to prevent the spread of infectious diseases.
- Map/track the spread of the virus throughout different locations
- Constantly update the number of people affected and provide real-time information
- Identify the catchment areas, vulnerable groups, health centers, and movement of carriers of the disease.
With these data, it was easier for governments, health bodies, and associations to use the power of GIS to visualize all of the health data during the outbreak and spread of Covid-19 and therefore employ the best tactics and practices to combat the virus.
The widespread use of GIS for COVID-19 response has demonstrated the power of geospatial thinking and the scalability, speed, and insight it provides.
More than simply mapping phenomena, GIS uses geography to furnish context for events in a common reference system.
by Chioma Innocent | Mon Jun, 2022 | Geoinfotech Blog, Geospatial technology, Service, Tips and Tricks |
How Can Gis Be Used To Estimate Flood Damage?
We are currently in the rainy season here in Nigeria. In many areas, as people are happy to have the rains, including farmers and ranchers, others are unhappy due to the damages the heavy rains could cause to roads and properties.
Many parts of the country are known to be unable to withhold the impact of heavy rains which can lead to flooding, erosion, damage to buildings and infrastructure, loss of crops and livestock, and landslides that can threaten human life and disrupt transport and communication.
Geographic Information Systems (GIS) provides a broad range of tools for determining areas affected by floods and for forecasting areas that are likely to be flooded due to high water levels in a river. GIS will be extensively used to assemble information from different maps, aerial photographs, satellite images, and digital elevation models (DEM).
Input parameters such as flood data, land use, socioeconomic data, and rainfall values are used to estimate flood damage. For any particular geographic area, it is important to have certain tools and software. These programs and data sets are top-notch for the GIS researcher.
Computer programs:
- ArcGIS 10 (ArcView)
- HEC-GeoHMS for ArcGIS 10
- HEC-GeoRAS for ArcGIS 10
- ArcHydro tools (the version that works with ArcGIS 10)
Required Datasets:
- Digital Elevation Model (DEM) for the study area;
- SSURGO soil data;
- Land cover grid from USGS;
- Hydrography data
Several models and tools can be developed using these parameters. It all depends on the discretion of the researcher, their knowledge, expertise, and the purpose of the research.
If used properly, these tools can be used to determine information, including hazard, vulnerability, financial losses, the risk to life, and prevention, and control of dangerous floods.
