For vertical-looking radars (VLRs), it is typically assumed that insects maintain a steady and approximately horizontal flight attitude as they pass through the radar beam, allowing for the estimation of insect morpho...
详细信息
For vertical-looking radars (VLRs), it is typically assumed that insects maintain a steady and approximately horizontal flight attitude as they pass through the radar beam, allowing for the estimation of insect morphologicalparameters by measuring the radar cross section (RCS) for a ventral aspect. However, for tracking radars, which dynamically track and monitor insects, the attitude of the insect relative to the radar beam constantly changes. This dynamic change in attitude renders traditional insect morphological parameter estimation methods based on the ventral-aspect RCS ineffective. This article proposes a novel method for estimating the morphologicalparameters of insects in nonhorizontal flight attitudes. By determining the azimuth and pitch angles of the insect's body axis relative to the radar antenna reference coordinate system and reconstructing the scattering matrix (SM) of the insect from nonhorizontal attitudes to a horizontal attitude, we achieve the estimation of morphologicalparameters for insects in nonhorizontal attitudes. The effectiveness of the proposed method is validated using a fully polarimetric multiangle observation dataset of 33 insects from six species measured in a microwave anechoic chamber. The mean relative errors (MREs) in estimating the mass and length of the insects across 20 different observation angles are 20.06% and 12.85%, respectively. Compared to estimates obtained without making the correction, the accuracy of mass and body length estimation is improved by 19.80% and 13.79%, respectively.
This paper proposes a reverse procedure detection method for space target streaks based on motion parameterestimation. According to the phase shift characteristics of the spectrum, the interframe phase difference is ...
详细信息
This paper proposes a reverse procedure detection method for space target streaks based on motion parameterestimation. According to the phase shift characteristics of the spectrum, the interframe phase difference is used to obtain the displacement vectors of the target streak and image background, and then the morphologicalparameters of the target streak are estimated. In addition, a streak window is designed on the basis of the parameters, utilizing the local grayscale correlation in two image frames to carry out target searching and positioning with the interval of the target displacement vector. Images from different scenes are used to evaluate the adaptability of our method, and the experimental results suggest that the expected targets can be detected successfully with subpixel precision in all telescope operating modes. The proposed frequency-domain reverse procedure detection method avoids the problem of fake target confirmation caused by blind detection in traditional methods and overcomes the interference produced when the target streak passes through a bright star. Moreover, first target tracking and then positioning, which cannot be performed with time-domain methods, can be achieved. Our proposed method is attractive for multiple applications, such as space target cataloging, early warning and orbit prediction.
Insect morphologicalparameters, including mass and length, are crucial for species identification. Entomological radar can estimate morphologicalparameters by establishing mappings from insect radar cross section (R...
详细信息
Insect morphologicalparameters, including mass and length, are crucial for species identification. Entomological radar can estimate morphologicalparameters by establishing mappings from insect radar cross section (RCS) estimators to them. Current high-accuracy methods relying on absolute RCS estimators are sensitive to echo intensity. When applied to radars without angle measurement capability, these methods may underestimate morphologicalparameters. This underestimation arises from the inability of such radars to compensate for reduced echo intensity caused by insects deviating from the beam center. A method using single-frequency echo intensity-independent estimators (EIIEs) was attempted;however, it could only estimate the mass of insects below 200 mg with limited accuracy. This article explores the use of multifrequency EIIEs (MFEIIEs) to enhance the estimation of insect mass and length. Based on the multifrequency scattering dataset for 159 insects measured in an anechoic chamber, the insect multifrequency scattering matrix (SM) was studied. The study revealed that four EIIEs, including the amplitude ratio and phase difference of SM eigenvalues, and two relative RCS features related to the shape of the insect polarization pattern, were correlated with insect mass and length with varied correlations with frequency. Subsequently, morphological parameter estimation was achieved by establishing the mappings from MFEIIEs to mass and length using a random forest algorithm. The presented dataset demonstrated that this method was suitable for insects below 1000 mg. Finally, the method's effectiveness and robustness were demonstrated through field measurements on 160 insects, which yielded mean relative estimation errors of 21.82% for mass and 13.18% for length.
暂无评论