Design, fabrication, and evaluation of a large-area hybrid solar simulator for remote sensing applications.

Solar irradiance variations have a direct effect on the accuracy and repeatability of identifying spectral signatures in the remote sensing field experiments. Solar simulators have been deployed to allow for testing under controlled and reproducible laboratory conditions. However, it is difficult and expensive to make a large-area solar simulation with the appropriate spectral content and spatial uniformity of irradiance.

Aerial target spatial-spectral discrimination for imaging spectrometer based on the acousto-optic tunable filter.

To solve the problem caused by jamming, an acousto-optic tunable filter (AOTF)-based imaging spectrometer and a corresponding spatial-spectral discrimination method are proposed for aerial targets. The system has the capability of staring imaging and is electronically tunable, which provides the spatial location and a distinguishable spectral feature in a few images. Since AOTF operates in a frame mode, the spectral brightness of the targets can be predicted by Kalman filtering, like with the motion model.

Acquirement of anisotropy reflectance with the multi-directional hyperspectral remote sensing simulation facility (MHSRSF).

The reflectance factor acquired in laboratory makes a good contribution to spectral library for remote sensing. However, this reflectance factor is a different quantity from that acquired in the field. To bridge the gap between them, the spectral and the spatial characteristics of sunlight and skylight are analyzed.

A Flight Direction Design Method for Airborne Spectral Imaging Considering the Anisotropy Reflectance of the Target in Rugged Terrain.

An excellent mission plan is the prerequisite for the acquisition of high quality airborne hyperspectral images which are useful for environmental research, mining etc. In order to minimize the radiance non-uniformity caused by the anisotropic reflectance of targets, the flight direction is mostly designed on the solar azimuth or 180° from it for whiskbroom and pushbroom imagers. However, the radiance to the observer is determined not only by the reflectance of the target, but also by the terrain, the illumination direction and the observation direction.

SWIR AOTF Imaging Spectrometer Based on Single-pixel Imaging.

An acousto-optic tunable filter (AOTF) is a new type of mono-wavelength generator, and an AOTF imaging spectrometer can obtain spectral images of interest. However, due to the limitation of AOTF aperture and acceptance angle, the light passing through the AOTF imaging spectrometer is weak, especially in the short-wave infrared (SWIR) region. In weak light conditions, the noise of a non-deep cooling mercury cadmium telluride (MCT) detector is high compared to the camera response.

A Combined Quantitative Evaluation Model for the Capability of Hyperspectral Imagery for Mineral Mapping.

To analyze the influence factors of hyperspectral remote sensing data processing, and quantitatively evaluate the application capability of hyperspectral data, a combined evaluation model based on the physical process of imaging and statistical analysis was proposed. The normalized average distance between different classes of ground cover is selected as the evaluation index. The proposed model considers the influence factors of the full radiation transmission process and processing algorithms.

Comparing analysis of multispectral and polarimetric imaging for mid-infrared detection blindness condition.

When detection blindness occurs due to thermal crossover for conventional broadband mid-infrared (IR) imaging, multispectral and polarimetric imaging present their advantages in solving the problem to some extent. However, neither of them is satisfactory for all application environments. In this paper, we demonstrate two types of detection blindness situations, analyze their corresponding mechanism, and identify the respective optimum application condition for multispectral and polarimetric imaging.

Field imaging system for hyperspectral data, 3D structural data and panchromatic image data measurement based on acousto-optic tunable filter.

The hyperspectral data and 3D structural data are highly useful in botanical research. But, the two types of information are often acquired separately and hard to be combined. In this work, a novel dual-path configuration based on acousto-optical tunable filter (AOTF) is proposed to acquire an image, structural and hyperspectral information within one acquisition process by a combination of laser triangulation.

A "Skylight" Simulator for HWIL Simulation of Hyperspectral Remote Sensing.

Even though digital simulation technology has been widely used in the last two decades, hardware-in-the-loop (HWIL) simulation is still an indispensable method for spectral uncertainty research of ground targets. However, previous facilities mainly focus on the simulation of panchromatic imaging. Therefore, neither the spectral nor the spatial performance is enough for hyperspectral simulation.

MWIR thermal imaging spectrometer based on the acousto-optic tunable filter.

Mid-wavelength IR (MWIR) thermal imaging spectrometers are widely used in remote sensing, industrial detection, and military applications. The acousto-optic tunable filter (AOTF)-based spectrometer has the advantages of fast tuning, light weight, and no moving parts, which make it ideally suited for MWIR applications. However, when designing an AOTF imaging spectrometer, the traditional method uses a refractive grating or parallel glass model in optical design software to simulate the AOTF, lowering the imaging performance of the optical system.

Chromatic aberrations correction for imaging spectrometer based on acousto-optic tunable filter with two transducers.

The acousto-optic tunable filter (AOTF) with wide wavelength range and high spectral resolution has long crystal and two transducers. A longer crystal length leads to a bigger chromatic focal shift and the double-transducer arrangement induces angular mutation in diffracted beam, which increase difficulty in longitudinal and lateral chromatic aberration correction respectively. In this study, the two chromatic aberrations are analyzed quantitatively based on an AOTF optical model and a novel catadioptric dual-path configuration is proposed to correct both the chromatic aberrations.

Spectral super-resolution reflectance retrieval from remotely sensed imaging spectrometer data.

Existing atmospheric correction methods retrieve surface reflectance keeping the same nominal spectral response functions (SRFs) as that of the airborne/spaceborne imaging spectrometer radiance data. Since the SRFs vary dependent on sensor type and configuration, the retrieved reflectance of the same ground object varies from sensor to sensor as well. This imposes evident limitations on data validation efforts between sensors at surface reflectance level.

[Analysis of optic crosstalk correction for pushbroom hyperspectral data].

Based on the imaging process of pushbroom hyperspectral imager, a correction method for optic crosstalk was developed. An area that has white calibration target was selected as reference data. The target pixels crosstalk quantity was gained using the subtraction between the two lines of reference data, and it was fitted to restrain noise.

A digital sensor simulator of the pushbroom Offner hyperspectral imaging spectrometer.

Sensor simulators can be used in forecasting the imaging quality of a new hyperspectral imaging spectrometer, and generating simulated data for the development and validation of the data processing algorithms. This paper presents a novel digital sensor simulator for the pushbroom Offner hyperspectral imaging spectrometer, which is widely used in the hyperspectral remote sensing. Based on the imaging process, the sensor simulator consists of a spatial response module, a spectral response module, and a radiometric response module.

Analyzing the effect of synthetic scene resolution, sampling interval, and signal-to-noise ratio on hyperspectral imaging sensor simulations.

Sensor simulation modeling is an important tool for the design of new earth imaging systems. As the input of the model, the characteristics of the synthetic spectral scene image data cube (SSSIDC) play an important role in the accuracy of the simulation. Based on a general sensor simulation model, the effects of SSSIDC resolution, sampling interval (SI), and signal-to-noise ratio (SNR) on simulated data are analyzed.

Uncertainty propagation algorithm from the radiometric calibration to the restored earth observation radiance.

The uncertainty of the radiometric calibration affects the accuracy of the earth observation (EO) radiance restored from the remote sensing digital number (DN) data. However, it has not been intensively analyzed whether they are equivalent to each other. The algorithm to deduce the uncertainty of the restored EO radiance in the solar-reflective spectral range (400-2500 nm) along the uncertainty propagation chain in the radiometric calibration process is proposed.

[Study on the modeling of earth-atmosphere coupling over rugged scenes for hyperspectral remote sensing].

Adjacency effects may introduce errors in the quantitative applications of hyperspectral remote sensing, of which the significant item is the earth-atmosphere coupling radiance. However, the surrounding relief and shadow induce strong changes in hyperspectral images acquired from rugged terrain, which is not accurate to describe the spectral characteristics. Furthermore, the radiative coupling process between the earth and the atmosphere is more complex over the rugged scenes.