Aerial Mapping Airborne Multi-spectral
Airborne imaging systems obtain high-resolution images in a wide range of spectral modes including:
1. Visible/Near Infrared (VNIR) multi-spectral scanners, which produce images similar to infrared aerial photography and VNIR satellites such as IKONOS and SPOT. The infrared bands include much information about vegetation, and for this reason, multi-spectral scanners are used primarily in agriculture and forestry.
Airborne multi-spectral images present special challenges for image processing mapping because each object (e.g. trees) has a range of values. One solution is to “segment” the image into objects and analyse the spectral characteristics of the entire object. The image above shows how the range of colours across each tree crown, from fully sunlit to shaded, has been averaged for the crown polygons. The different spectra then can be used to distinguish different types of tree.
2. Thermal Images can be used to measure surface temperature to an accuracy of less than one tenth of a degree. Terranean has extensive experience using radio-linked airborne thermal sensors to map fires in near real time. The images are also useful in monitoring irrigation systems, where leaf temperature increases immediately with water stress. VNIR sensors only detect water stress once the growth of the plant, and therefore productivity, has suffered.
This thermal image of cotton crops demonstrates the leaf temperature of the plants. High leaf temperature is the first sign of water stress.
3. Hyperspectral sensors provide images with more than 200 spectral bands, basically a continuous measurement of the spectrum of the Earth’s surface. Hyperspectral mapping of geology and minerals is based on well-defined and tested methodologies, the most effective method for mapping the chemical composition of soil and rock in arid areas, where vegetation does not obscure the substrate. Terranean’s software uses mineral spectra measured in the laboratory or from the USGS library of mineral spectrum to analyse hyperspectral images, in order to determine the chemical composition of rocks and soil or map the concentration of specific minerals.
Terranean software matches mineral spectra to hyperspectral images.