Remote-sensing Camera Research Articles

Analysis and Control of Precision Machining Error for Spatial Angle Parts of Remote-Sensing Camera

Aiming at the problem of low machining accuracy of remote-sensing camera parts with spatial angle, this study analyzed the causes from human, machine, material, method, environment, and measurement, and proposed an experimental analysis method based on the spatial rotation of machine tool spindle according to the linkage machining function of the five-axis machining center. The cutting experiment was carried out through the self-built benchmark of the machine tool, and the machining errors of the machine tool spindle with different spatial angles were studied. The precision machining of the parts with spatial angles was realized by taking measures such as machine tool correction and numerical control program compensation. The experiment proved that this method is feasible and effective.

On-Orbit High-Accuracy Geometric Calibration for Remote Sensing Camera Based on Star Sources Observation

The on-orbit calibration technology for internal and external parameters of remote sensing camera is the key to guaranteeing the imaging quality and positioning accuracy. Conventional landmark-based methods are not suitable for satellite missions where landmarks do not work nor for the on-orbit autonomous calibration of large remote sensing constellation. Hence, we introduced an on-orbit geometric calibration method based on star sources observation. By adjusting the satellite attitude, the camera and star sensor can simultaneously detect the star sources. Taking the star sources as control points, a high-accuracy “camera-star sensor” joint geometric calibration model integrating the space–time effects and optical imaging is established, which precisely decouples the deviations caused by the relativistic effects, the distortion of internal parameters, and the bias of external parameters. Furthermore, the procedures of the method are designed for on-orbit autonomous calibration. On-orbit experiments were carried out in several satellites, such as Jilin-1 ShiPin07 (JL-1 SP07). The results showed that the accuracy of internal calibration could reach 0.052” and the error of external installation matrix was within ±1.4”. Therefore, the method is attractive for actualizing on-orbit autonomous geometric calibration accurately and complements the conventional methods where the availability of landmarks is hard.

A Large-Aperture Remote Sensing Camera Calibration Method Based on Stellar and Inner Blackbody

Radiometric calibration of satellites is one of the core technologies for analyzing satellite data quantitatively. For large-aperture remote sensing cameras, the blackbody is placed in the rear optical path due to its weight and size. As a result, the front optics’ self-emission cannot be evaluated when the inner blackbody is observed. To achieve full optical path calibrations, stars are used as radiation calibration sources for large-aperture cameras. In high energy concentration detection systems, the point spread function (PSF), intrapixel sensitivity (IPS), capacitive coupling and sampling phase may cause some energy of the point source to be lost, resulting in an energy difference between the extended and point sources. It is important to note that conventional aperture photometry is not always the ideal method for obtaining high-precision photometry. This paper proposes a method for compensation of point-source signals based on capacitive coupling correction, PSF reconstruction and IPS model, and establishes a response conversion model for stellar and inner blackbodies. According to calibration coefficients based on stars and inner blackbody, the error between the star calibration coefficient and the inner blackbody calibration coefficient is 0.18%, which is better than 59.4% before the proposed method was applied. The error between the two methods can be stabilized within 0.3% within 140 days of the launch of the satellite.

Image Motion of Remote Sensing Camera With Wide Field of View Over the Antarctic and Arctic

Imaging by the remote sensing camera with a wide field of view (WFV) is of great significance in the issue of polar environment. However, the instability of the image motion velocity poses a huge challenge to the observation task since the direction of the earth's rotation velocity keeps changing in the polar regions. The edge blur of polar image by the camera with the WFV is usually ignored. Therefore, a specific theoretical model that the camera images over the polar region is supposed to describe the instability distinctly. Mathematical expressions of the image motion velocity field are obtained with a novel method of velocity projection and coordinate transformation. The quantitative analysis of simulation reveals that the increasing anisotropy of the instantaneous image motion velocity field gets most significant near the poles. The value of modulation transfer function at the edge of the field of view decreased by 0.33%, which results in a discrepancy of sharpness in an image. The model is capable of explaining the edge blur, of the image from BNU-1, which provides a theoretical basis for the image motion compensation strategy of cameras with the WFV.

On-Orbit Calibration of Installation Matrix between Remote Sensing Camera and Star Camera Based on Vector Angle Invariance.

To achieve photogrammetry without ground control points (GCPs), the precise measurement of the exterior orientation elements for the remote sensing camera is particularly important. Currently, the satellites are equipped with a GPS receiver, so that the accuracy of the line elements of the exterior orientation elements could reach centimeter-level. Furthermore, the high-precision angle elements of the exterior orientation elements could be obtained through a star camera which provides the direction reference in the inertial coordinate system and star images. Due to the stress release during the launch and the changes of the thermal environment, the installation matrix is variable and needs to be recalibrated. Hence, we estimate the cosine angle vector invariance of a remote sensing camera and star camera which are independent of attitude, and then we deal with long-term on-orbit data by using batch processing to realize the accurate calibration of the installation matrix. This method not only removes the coupling of attitude and installation matrix, but also reduces the conversion error of multiple coordinate systems. Finally, the geo-positioning accuracy in planimetry is remarkably higher than the conventional method in the simulation results.

Speed Control for the Pitching Axis of a Remote Sensing Camera Using an Improved Active Disturbance Rejection Controller

This paper proposes the theoretical framework and the experimental application of an improved active disturbance rejection controller (ADRC) to speed control for the pitching axis of a remote sensing camera. Mechanical model of the pitching axis, mechatronics model of the speed control system for the pitching axis, and speed algorithm model of a permanent magnet synchronous motor are established. Control rates of the extended state observer (ESO) and the nonlinear state error feedback (NSEF) of the traditional ADRC are improved using a new nonlinear function. The nonlinear dynamics, model uncertainty, and external disturbances of the speed control system are extended to a new state, and the improved ESO is implemented to observe this state. The overtime variation of the speed control system is predicted and compensated for in real time using the improved ESO. The nonlinear integration method is adopted to nonlinearly combine the differential and the error differential by the improved NSEF. Subsequently, high-quality control is provided to the system. Simulation and experimental verification for the speed control system for the pitching axis of a remote sensing camera are conducted. Results show the effectiveness of the proposed controller.

大畸变航天遥感相机焦平面弧形拼接

大畸变航天遥感相机焦平面弧形拼接

Thermal Stability Optimization of the Luojia 1-01 Nighttime Light Remote-Sensing Camera's Principal Distance.

The instability of the principal distance of the nighttime light remote-sensing camera of the Luojia 1-01 satellite directly affects the geometric accuracy of images, consequently affecting the results of analysis of nighttime light remote-sensing data. Based on the theory of optical passive athermal design, a mathematical model of optical-passive athermal design for principal distance stabilization is established. Positive and negative lenses of different materials and the mechanical structures of different materials are matched to optimize the optical system. According to the index requirements of the Luojia 1-01 camera, an image-telecentric optical system was designed under the guidance of the established mathematical model. In the temperature range of −20 °C to +60 °C, the principal distance of the system changes from −0.01 μm to +0.28 μm. After on-orbit testing, the geometric accuracy of the designed nighttime light remote-sensing camera is better than 0.20 pixels and less than index requirement of 0.3 pixels, which indicating that the principal distance maintains good stability on-orbit and meets the application requirements of nighttime light remote sensing.

空间相机碳纤维复合材料主次镜连接筒设计

空间相机碳纤维复合材料主次镜连接筒设计

微纳遥感相机一体式超轻主支撑结构优化设计

微纳遥感相机一体式超轻主支撑结构优化设计

Seasonal and predator-prey effects on circadian activity of free-ranging mammals revealed by camera traps.

Endogenous circadian and seasonal activity patterns are adapted to facilitate effective utilisation of environmental resources. Activity patterns are shaped by physiological constraints, evolutionary history, circadian and seasonal changes and may be influenced by other factors, including ecological competition and interspecific interactions. Remote-sensing camera traps allow the collection of species presence data throughout the 24 h period and for almost indefinite lengths of time. Here, we collate data from 10 separate camera trap surveys in order to describe circadian and seasonal activity patterns of 10 mammal species, and, in particular, to evaluate interspecific (dis)associations of five predator-prey pairs. We recorded 8,761 independent detections throughout Northern Ireland. Badgers, foxes, pine martens and wood mice were nocturnal; European and Irish hares and European rabbits were crepuscular; fallow deer and grey and red squirrels were diurnal. All species exhibited significant seasonal variation in activity relative to the timing of sunrise/sunset. Foxes in particular were more crepuscular from spring to autumn and hares more diurnal. Lagged regression analyses of predator-prey activity patterns between foxes and prey (hares, rabbits and wood mice), and pine marten and prey (squirrel and wood mice) revealed significant annual and seasonal cross-correlations. We found synchronised activity patterns between foxes and hares, rabbits and wood mice and pine marten and wood mice, and asynchrony between squirrels and pine martens. Here, we provide fundamental ecological data on endemic, invasive, pest and commercially valuable species in Ireland, as well as those of conservation importance and those that could harbour diseases of economic and/or zoonotic relevance. Our data will be valuable in informing the development of appropriate species-specific methodologies and processes and associated policies.

Micro Coded-Aperture Lead-In of Light for Calibrating Remote Sensing Cameras

We investigate the geometric calibration of a remote sensing camera using a micro coded-aperture lead-in (CAL) of light. A CAL can transform a light beam into multiple sub-beams with a precisely known diffraction angle. The multiple sub-beams can be considered as light sources of multiple point-targets at infinity. We experimentally confirm that this method can achieve an accuracy of approximately $101~\mu \text{m}$ and is simple to calibrate. This method has the potential to be used in the calibration of the interior parameters of optical remote sensors on the ground and in orbit.

Suppressing the image smear of the vibration modulation transfer function for remote-sensing optical cameras.

In on-board photographing processes of satellite cameras, the platform vibration can generate image motion, distortion, and smear, which seriously affect the image quality and image positioning. In this paper, we create a mathematical model of a vibrating modulate transfer function (VMTF) for a remote-sensing camera. The total MTF of a camera is reduced by the VMTF, which means the image quality is degraded. In order to avoid the degeneration of the total MTF caused by vibrations, we use an Mn-20Cu-5Ni-2Fe (M2052) manganese copper alloy material to fabricate a vibration-isolation mechanism (VIM). The VIM can transform platform vibration energy into irreversible thermal energy with its internal twin crystals structure. Our experiment shows the M2052 manganese copper alloy material is good enough to suppress image motion below 125 Hz, which is the vibration frequency of satellite platforms. The camera optical system has a higher MTF after suppressing the vibration of the M2052 material than before.

Application of High Speed Serial Data Transmission System in Remote Sensing Camera

In order to meet the system needs of miniaturization, real-time, high-speed data and high reliability transmission in remote sensing camera, a high-speed serial protocol based on high-speed serial/parallel converter SerDes is proposed. For the SerDes high-speed serial data transmission chip for the physical layer, FPGA for the link layer of the communication system, design high-speed serial transmission communication protocol. Through the development of a simplified protocol for the upper user to provide a simple data interface. The system completed the data rate of 12.5Gbps point to point high-speed transmission. Verification is done by sending a pseudo-random code between boards. System work 3 hours, the measured bit error rate is less than 10 -12 .

航天遥感相机及参数优化方法

航天遥感相机及参数优化方法

Comparing the Use of Camera Traps and Farmer Reports to Study Crop Feeding Behavior of Moor Macaques (Macaca maura)

Investigating crop feeding patterns by primates is an increasingly important objective for primatologists and conservation practitioners alike. Although camera trap technology is used to study primates and other wildlife in numerous ways, i.e., activity patterns, social structure, species richness, abundance, density, diet, and demography, it is comparatively underused in the study of human–primate interactions. We compare photographic (N = 210) and video (N = 141) data of crop feeding moor macaques (Macaca maura) from remote sensor cameras, functioning for 231 trap days, with ethnographic data generated from semistructured interviews with local farmers. Our results indicate that camera traps can provide data on the following aspects of crop feeding behavior: species, crop type and phase targeted, harvesting technique used, and daily and seasonal patterns of crop feeding activity. We found camera traps less useful, however, in providing information on the individual identification and age/sex class of crop feeders, exact group size, and amount of crops consumed by the moor macaques. While farmer reports match camera trap data regarding crop feeding species and how wildlife access the gardens, they differ when addressing crop feeding event frequency and timing. Understanding the mismatches between camera trap data and farmer reports is valuable to conservation efforts that aim to mitigate the conflict between crop feeding wildlife and human livelihoods. For example, such information can influence changes in the way certain methods are used to deter crop feeding animals from damaging crops. Ultimately, we recommend using remote-sensing camera technology in conjunction with other methods to study crop feeding behavior.

大视场空间遥感相机的像速场及图像传感器曝光积分控制

大视场空间遥感相机的像速场及图像传感器曝光积分控制

Measuring Driving Behaviors from Live Video

Because of the technical and cost constraints on traditional measurement methods, there is a lack of long-term driving behavior data from natural traffic scenes, and this situation has been hindering research progress into driving behavior modeling and other related topics. Thanks to high-definition cameras and advanced visual measurement methods, traffic visual detection is entering a new stage of traffic visual measurement, and thus we can expect to achieve accurate segmentation, positioning, and measurement for road vehicles from live video to meet the requirement for field test data in behavior modeling. To measure driving behaviors in a cost-effective manner, the authors propose a comprehensive visual measurement approach that could perform well in complex traffic scenes. Specifically, they describe a procedure for traffic visual measurement, some preliminary algorithms, and some representative experimental results. Comparisons between the proposed method and three traditional ones (driving simulator, in-vehicle data recorder, and remote-sensing camera) indicate that the biggest advantage of the proposed method is it can measure driving behaviors from live video. Hence, the ongoing research will greatly benefit cognition in driving behavior models.

基于面阵CCD的时间延时积分模式的空间相机自动对焦

基于面阵CCD的时间延时积分模式的空间相机自动对焦

Comparison of SNR image quality metrics for remote sensing systems

Different definitions of the signal-to-noise ratio (SNR) are be- ing used as metrics to describe the image quality of remote sensing systems. It is usually not clear which SNR definition is being used and what the image quality of the system is when an SNR value is quoted. This paper looks at several SNR metrics used in the remote sensing community. Image simulations of the Kodak Space Remote Sensing Camera, Model 1000, were produced at different signal levels to give insight into the image quality that corresponds with the different SNR metric values. The change in image quality of each simulation at different signal levels is also quantified using the National Imagery Interpretability Rating Scale (NIIRS) and related to the SNR metrics to better under- stand the relationship between the metric and image interpretability. An analysis shows that the loss in image interpretability, measured as DNI- IRS, can be modeled as a linear relationship with the noise-equivalent change in reflection (NE Dr). This relationship is used to predict the val- ues that the various SNR metrics must exceed to prevent a loss in the interpretability of the image from the noise. © 2001 Society of Photo-Optical