Application of Hyperspectral Imager in Disguised Target Recognition(part 2)
author: Yilia
2023-01-13
1.4 Typical camouflaged targets in the background of vegetation (grassland)
| Instrument | Recommended instrument model |
| Hyperspectral imager |
|
| Fieldspec Spectroradiometer |
|
Comparing the camouflage effect of camouflaged targets in the visible light and near-infrared hyperspectral bands, it is found that in the visible light band, even if the objects have similar colors, but the materials are different, the change rate of the spectral curve will be different; in the near-infrared band, the spectral reflectance of different objects exists. There is a large difference, but the rate of change of the spectral curve is relatively small.
We use a full-band surface feature spectrometer (such as ATP9110-25H Fieldspec spectrometer from Optosky), and the measured spectral curve of the high imitation camouflage net is very similar to the spectral curve of the shrub leaf surface between 400 and 1300 nm. , and has the characteristics of vegetation "red edge" and green strong reflection peak in visible light band, it is not easy to distinguish vegetation and camouflage net spectrum in this band area. This is a very good high imitation green camouflage net.
1.5. Investigating whether there are Tibetans in the cave
Cave warfare and tunnel warfare are also common methods of warfare, and have been widely used since World War II. Even if it is modern warfare, it is also a good method.The caves are mainly distributed in the eastern and southern parts of Afghanistan, which are controlled by the Taliban.Typical caves include natural limestone caverns, tunnels and man-made passages.There are also tunnel-type bunkers right on the surface of the mountain, about 10-30 feet deep.
Around 2010, the United States used the airborne SE-BASS long-wave infrared hyperspectral payload to carry out research work on detecting hidden targets such as underground caves (as shown in Figure 20) and abandoned mine mouths.
In the same way, if there are people in the cave, they can be detected and confirmed by long-wave infrared hyperspectral imaging (such as Optosky GA320 gas scanner), based on the temperature characteristics and the carbon dioxide absorption peak spectrum (3.4μm) characteristics of human breath. . The United States adopted a 24-hour day and night hyperspectral detection method in Afghanistan, based on the fact that the surrounding environment of the cave changes greatly day and night, while the cave itself changes relatively little, as a basis for detecting whether there are combat soldiers hiding in the cave.
1.6. Landmine and explosive detection research
In the late 1980s, the United States, the United Kingdom, France, Canada, Belgium, Sweden and other countries successively carried out hyperspectral mine detection technology research. In 1994, DARPA developed HMD (Hyperspectral Mine Detection)
The project aims to study the technology of hyperspectral imaging to detect landmines, and the research has confirmed that it has detection capabilities from visible light to long-wave infrared. Among them, in the long-wave range, the airborne AHI long-wave infrared hyperspectral imaging spectrometer was used to carry out the test, the spatial resolution is 0.5 mrad, and the number of spectral segments is 256. The infrared radiation spectrum changes near the mines buried in the soil were studied, and the real-time processing algorithm was carried out. Research. The histogram of the experimental data processing is shown in Figure 22, and the histogram of the mine and the surrounding environment can be clearly distinguished.
In 2006, DRDC successfully completed the airborne real-time landmine detection test. Subsequently, further research showed that it has the ability to detect landmines in the visible, near-infrared and thermal infrared bands. The best detection band in the thermal radiation area is 4.2-5 μ m, 8~9.5 μm, and 3~4.2 μm during the day.
From 2002 to 2003, the United States launched an airborne hyperspectral imaging landmine detection test, using visible near-infrared/short-wave infrared COMPASS hyperspectral payloads, with 250 spectral segments and a flight altitude of 4,000 feet. The United Kingdom launched the DSTL anti-landmine countermeasure program at the same time. Airborne and ground hyperspectral imaging tests have been carried out in the visible and near-infrared bands, and it has been confirmed that hyperspectral can be used to detect the spectral characteristics of vegetation or soil near landmines. The test scene is shown in Figure 24.
Conclusion：
With the advancement of science and technology, remote sensing technology has also developed rapidly and is becoming more and more mature. Its advantages of all-round, multi-scale, all-weather, all-weather and refined imaging make remote sensing reconnaissance more direct and accurate, and it is more sharp in discovering suspected targets and revealing hidden targets. Remote sensing technology greatly restricts traditional camouflage technology methods and equipment, and poses more severe challenges to the development of camouflage technology, forcing camouflage technology to find new ways to seek more effective countermeasures and technical methods.
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