Wide Swath and High Resolution Airborne Pushbroom Hyperspectral Imager (WiSHiRaPHI) is the new-generation airborne hyperspectral imager instrument of China, aimed at acquiring accurate spectral curve of target on the ground with both high spatial resolution and high spectral resolution. The spectral sampling interval of WiSHiRaPHI is 2.4 nm and the spectral resolution is 3.5 nm (FWHM), integrating 256 channels coving from 400 nm to 1000 nm. The instrument has a 40-degree field of view (FOV), 0.125 mrad instantaneous field of view (IFOV) and can work in high spectral resolution mode, high spatial resolution mode and high sensitivity mode for different applications, which can adapt to the Velocity to Height Ratio (VHR) lower than 0.04. The integration has been finished, and several airborne flight validation experiments have been conducted. The results showed the system’s excellent performance and high efficiency.

Aiming at the problem wherein temperature inversion accuracy is unstable due to the major differences in atmospheric transmittance under various observation paths, a method for measuring radiation characteristics of an aircraft engine’s hot parts and skin using a cooled middle-wave infrared camera is proposed. Based on the analysis of the aircraft’s infrared radiation characteristics, the atmospheric transmission model of any observation path was revised, the absolute radiation correction model was established, and the temperature inversion equation was calculated. Then, we used the quasi-Newton method to calculate the skin temperature and discussed uncertainty sources. After the theoretical study, an outfield test was carried out. A middle-wave infrared camera with a wavelength of 3.7–4.8 μm was applied to the actual experimental observation of the turbofan civil aviation aircraft. The ground observation distance was 15 km, and the flying height was 3 km. When implementing temperature inversion with the method presented in this paper, the surface temperature of the aircraft engine hot parts was 381 K, the correction uncertainty was ±10 K, the surface temperature of the skin was 296 K, and the correction uncertainty was ±6 K. As the experiment showed, the method in this paper can effectively implement infrared target temperature inversion and provide a reference for the quantification of infrared data.

Automatic image stitching and high-precision photogrammetry have been active research fields. This paper proposes a novel stitching method for high-precision, low-overlap thermal infrared array scanning (TIRAS) images. The approach corrects the TIRAS camera’s internal parameters, external orientation (EO) elements, and planar projection errors by calculating three homography matrices. Firstly, we establish collinearity equations using the calibrated internal parameters and EO elements with errors and further compute the direct projection transformation model of the original image. Then, we propose a global error optimization model based on a fixed framework according to the midpoints of the alignment point pairs of the correcting image and neighboring images. The homography matrix calculated by this model can relatively correct the EO element errors in the directly projected image. Finally, we calculate the homography matrix for the planar projection error correction using the UTM coordinates of geometric targets and their corresponding image coordinates and use the matrix to perform absolute error correction on the stitched wide-field image of the reprojected image. Comparing the proposed method with AutoStitch, Liu’s, and PTGui for MWIR image stitching results, it exhibits superior image stitching quality, without noticeable distortion or stretching, and with intact object structures. Besides, our method demonstrates outstanding positioning accuracy. Without ground control points, the optimal positioning accuracy is 0.7538m (RMSE), less than 1 pixel. In conclusion, the proposed stitching method showcases stable, automated, and highly accurate global error optimization capabilities, and it is also suitable to splice array remote sensing images equipped with a high-accuracy POS system.

Three-dimensional (3D) imaging technology enables simultaneously capturing two-dimensional surface features, depth information, and the spatial structure of the target area, offering broad applications in airborne imaging. Airborne area-array whisk-broom cameras are widely used at low-to-medium altitudes, providing high-speed height ratio airborne imaging due to their ability to achieve wide-field imaging through scanning. Currently, most airborne area-array whisk-broom imaging systems employ a vertical downward view, which limits their ability to fully capture the 3D characteristics of the target area. To overcome this limitation, this study proposes a backward-squint area-array wide-field whisk-broom imaging scheme. However, under such whisk-broom scanning conditions, a misalignment exists between the equivalent rotation axis of the image motion compensation mirror after optical path deflection and the roll scanning axis of the camera. To resolve this problem, we propose an accurate calculation model for non-coaxial image motion compensation. We conducted theoretical analysis and simulation experiments to validate the proposed method, achieving a stabilization accuracy better than 0.65 μrad per compensation cycle during a 45° backward squint and a 90° scanning width. Our research advances airborne area-array whisk-broom imaging technology by proposing a novel backward-squint imaging scheme and an innovative non-coaxial image motion compensation model, which significantly enhance in wide-field squint imaging and 3D modeling.