Aerial remote sensing is an essential technology meant for extracting information from the Earth’s surface using airborne onboard sensors. It is actually about receiving, measuring, and interpreting energy reflected or radiated by any object at the Earth’s surface that is exposed to any portion of the electromagnetic spectrum. Aerial remote sensing is of much significance in agriculture, forestry, urban planning, environmental monitoring, and disaster management.
Core Concepts of Aerial Remote Sensing
The fundamental core of aerial remote sensing is the acquisition of spatial data by using air-based platforms like airplanes, helicopters or even drone platforms referred to as Unmanned Aerial Vehicles or UAVs. Sensors generally operate over wavelengths on the visible, infrared, and microwave parts of the electromagnetic spectrum.
In the principle of aerial remote sensing, each material reflects and absorbs electromagnetic energy differently, providing every material with a unique spectral signature, which can be detected and analyzed by an instrument of remote sensing. The following is a summary of the most common forms of data obtained through aerial remote sensing:
Optical Imagery: It is gathered with sensors that are capable of sensing visible light; the images are produced almost as if they had been captured with a run-of-mill camera.
Multispectral Imagery: This is gathered in several specific wavelengths of the electromagnetic spectrum; further, both visible bands and infrared bands are mapped. This has a higher resolution level.
Hyperspectral Imagery: This goes beyond multispectral imaging to acquire information in hundreds of very narrow spectral bands; therefore, an even finer detail about material identification.
Thermal Imagery: Measures Infrared Radiation emitted by objects on Earth. Most generally, it is applied in detecting heat and temperature.
Types of Aerial Remote Sensing Platforms
Manned Aircraft: Conventional aircraft, such as planes and helicopters use advanced sensor arrays. Whenever it matters, it is preferable to use manned aircraft for filling large areas when sensitive applications such as forestry management, urban planning, or environmental monitoring are involved over large areas. Data generation of high resolution also suits well in manned aircraft.
UAS/Drones (UAVs): UAVs have found extensive applications in low-altitude aerial remote sensing within the last decade due to cost-effectiveness, flexibility, and ease of operation. Suitable applications requiring high spatial resolutions. Amenable to UAV studies where manned aircraft cannot reach the location. Excellent tools for short-term, site-specific studies.
Balloons or kites: Though not in great demand, these platforms do exist and find specific niche applications, especially in environmental and ecological monitoring where long-duration, low-altitude flights are involved.
Sensors Used in Aerial Remote Sensing
Passive Sensors: These sensors depend on the power available from other sources, primarily but not solely the sun, for measuring the reflected energy of the Earth’s surface. Most applications for optical, multispectral, and hyperspectral remote sensing take advantage of passive sensors that incorporate the only source of illumination necessary to acquire an image.
Active Sensors: Active sensors generate their power through beams of radar or laser and measure the returned backscattered energy. Typical examples include LiDAR, Light Detection and Ranging, and SAR, Synthetic Aperture Radar. LiDAR is applied in topographic mapping since it can also measure distances up to precision due to calibration of return pulses of laser pulses. SAR operates on the principle of microwave radiation to calculate the high-resolution images of the Earth’s surface and, hence, is particularly well-suited for applications such as mapping vegetation or surface deformation.
Data Processing in Airborne Remote Sensing
Radiometric Correction It removes sensor noise, atmospheric interference, and illumination non-uniformities. In simple words, it ensures that brightness values in the imagery reflect real surface properties.
Geometric correction represents the process through which remote sensing data are aligned in the framework of a coordinate system so that they can gain positional accuracy in geospatial positioning. Geometric correction corrects distortion caused by the movement of the sensor or curvature of the Earth so that remote sensing data may be made to map accurately onto a GIS platform.
Image Classification: The algorithms classify various surface features with known spectral signatures. Supervised classification entails known data trained by the algorithm, and in unsupervised classification, groupings of such pixels based on their spectral properties are relied on without an external guide.
Change Detection: The comparison of data gathered in two different periods can allow for measurements of change in land covers, vegetation, and other water bodies. In this case, such technology can very resourcefully be helpful to the environment in identifying change, urban expansion, and deforestation.
Applications of Aerial Remote Sensing in GIS
Agricultural: This type of data used in aerial scanning enables the practice of Precision Agriculture, which monitors crop health and nutrient deficiencies in crops using multispectral and hyperspectral data. It also scans to map soil properties and detects pest infestations much before they appear above the ground.
Forestry Management: Aerial remote sensing provides a means for monitoring forest health – tree canopy density and other illegal logging. It has been used in the mapping of biomass in forests, carbon storage, and other contributions toward climate change studies.
Urban Planning: The most valuable tool in applying aerial images toward urban planning and land use analysis is high-resolution aerial imagery. It will help identify growth patterns within the city, as well as point out areas that are experiencing infrastructural development, and trace changes occurring over time in the land.
Disaster Management: The most important activities during disaster response and recovery are aerial remote sensing. Areas devastated by flood disasters, wildfires, earthquakes, and the like can be rapidly assessed. This helps provide a basis for immediate determination of the scope of damage, relief planning, and prioritizing efforts for recovery.
Environmental Monitoring: Information coming from remote sensing data feeds environmental monitoring and includes information in terms of coastline erosion, desertification, and melting of glaciers. At the same time, it also accommodates water resource management with applications in mapping watersheds, water quality monitoring, and river and stream flow measurement.
Mineral and Geological Surveying: Aerial remote sensing, which includes hyperspectral and radar data, may be used for surface mineral detection and surface mineral mapping besides geological formations and the location of a potential mining area.
This puts it at the ranks of being one of the most powerful tools in the GIS sector; with it, one can derive valuable information on geospatial material for many applications. Improvement in sensor technology and processing algorithms along with their integration into UAVs is likely to take aerial remote sensing to the next level. Probably, all this happens in agricultural and urban planning by transforming the way one thinks and interplays with their environment by allowing the collection, analysis, and application of data.
