scholarly journals An Image Stitching Method for Airborne Wide-Swath HyperSpectral Imaging System Equipped with Multiple Imagers

2021 ◽  
Vol 13 (5) ◽  
pp. 1001
Author(s):  
Jingmei Li ◽  
Lingling Ma ◽  
Yongxiang Fan ◽  
Ning Wang ◽  
Keke Duan ◽  
...  
Keyword(s):  
Imaging System ◽  
Control Points ◽  
Image Simulation ◽  
Simulation Data ◽  
Error Sources ◽  
Ground Control Points ◽  
Orientation Model ◽  
Imaging Model ◽  
Better Than ◽  
Wide Swath

The field of view (FOV) of pushbroom hyperspectral imager is limited by the compromise of the detector scale and requirements of spatial resolution. Combining imagers along the sampling direction effectively expands its FOV and improves the imaging efficiency. Due to the small overlapping area between the adjacent imagers, stitching the images using traditional methods need a large amount of ground control points (GCPs) or additional strips, which reduce the efficiency of both image acquisition and processing. This paper proposed a new method to precisely stitch images acquired from multiple pushbroom imagers. First, the relative orientation model was built based on the homonymy points to calculate the relative relationship between the adjacent imagers. Then rigorous geometric imaging model was adopted to generate a seamless stitching image. Simulation data was used to verify the accuracy of the method and to quantitatively analyze the effect of different error sources. Results show that the stitching accuracy is better than two pixels. Overall, this method provides a novel solution for stitching airborne multiple pushbroom images, to generate the seamless stitching image with wide FOV.

scholarly journals Block Adjustment without GCPs for Chinese Spaceborne SAR GF-3 Imagery

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 4023 ◽  
Author(s):  
Guo Zhang ◽  
Qingwei Wu ◽  
Taoyang Wang ◽  
Ruishan Zhao ◽  
Mingjun Deng ◽  
...  
Keyword(s):  
High Accuracy ◽  
Control Points ◽  
Wuhan City ◽  
Error Sources ◽  
Geometric Calibration ◽  
Ground Control Points ◽  
Rational Polynomial ◽  
Sar Imagery ◽  
Orientation Parameters ◽  
Better Than

The Gaofen-3 (GF-3) satellite is the first C-band multi-polarization synthetic aperture radar (SAR) with the ability of high-accuracy mapping in China. However, the Ground Control Points (GCPs) are essential to ensure the accuracy of mapping for GF-3 SAR imagery at present. In this paper, we analyze the error sources that affect the geometric processing and propose a new block adjustment method without GCPs for GF-3 SAR imagery. Firstly, the geometric calibration of GF-3 image is carried out. Secondly, the rational polynomial coefficient (RPC) model is directly generated after the geometric calibration parameters compensation of each image. Finally, we solve the orientation parameters of the GF-3 images through DEM assisted planar block adjustment and conduct ortho-rectification. With two different imaging modes of GF-3 satellite, which include the QPSI and FS2, we carry out the block adjustment without GCPs. Experimental results of testing areas including Wuhan city and Hubei province in China show that the geometric mosaic accuracy and the absolute positioning accuracy of the orthophoto are better than one pixel, which has laid a good foundation for the application of GF-3 image in global high-accuracy mapping.

scholarly journals GEOMETRIC CALIBRATION OF ZIYUAN-3 THREE-LINE CAMERAS COMBINING GROUND CONTROL POINTS AND LINES

2016 ◽  
Vol XLI-B1 ◽  
pp. 163-168
Author(s):  
Jinshan Cao ◽  
Xiuxiao Yuan ◽  
Jianya Gong
Keyword(s):  
Ground Control ◽  
Calibration Model ◽  
Control Points ◽  
Charge Coupled Device ◽  
Geometric Calibration ◽  
Ground Control Points ◽  
The Look ◽  
Ccd Detectors ◽  
True Values ◽  
Better Than

Due to the large biases between the laboratory-calibrated values of the orientation parameters and their in-orbit true values, the initial direct georeferencing accuracy of the Ziyuan-3 (ZY-3) three-line camera (TLC) images can only reach the kilometre level. In this paper, a point-based geometric calibration model of the ZY-3 TLCs is firstly established by using the collinearity constraint, and then a line-based geometric calibration model is established by using the coplanarity constraint. With the help of both the point-based and the line-based models, a feasible in-orbit geometric calibration approach for the ZY-3 TLCs combining ground control points (GCPs) and ground control lines (GCLs) is presented. Experimental results show that like GCPs, GCLs can also provide effective ground control information for the geometric calibration of the ZY-3 TLCs. The calibration accuracy of the look angles of charge-coupled device (CCD) detectors achieved by using the presented approach reached up to about 1.0''. After the geometric calibration, the direct georeferencing accuracy of the ZY-3 TLC images without ground controls was significantly improved from the kilometre level to better than 11 m in planimetry and 9 m in height. A more satisfactory georeferencing accuracy of better than 3.5 m in planimetry and 3.0 m in height was achieved after the block adjustment with four GCPs.

scholarly journals PRELIMINARY GAOFEN-3 INSAR DEM ACCURACY ANALYSIS

2018 ◽  
Vol XLII-3 ◽  
pp. 173-177
Author(s):  
Q. Chen ◽  
T. Li ◽  
X. Tang ◽  
X. Gao ◽  
X. Zhang
Keyword(s):  
Three Dimensional ◽  
Ground Control ◽  
Calibration Model ◽  
Control Points ◽  
Error Sources ◽  
Alpine Regions ◽  
Ground Control Points ◽  
Range Function ◽  
Interferometric Phase ◽  
Dem Accuracy

GF-3 satellite, the first C band and full-polarization SAR satellite of China with spatial resolution of 1 m, was successfully launched in August 2016. We analyze the error sources of GF-3 satellite in this paper, and provide the interferometric calibration model based on range function, Doppler shift equation and interferometric phase function, and interferometric parameters calibrated using the three-dimensional coordinates of ground control points. Then, we conduct the experimental two pairs of images in fine stripmap I mode covering Songshan of Henan Province and Tangshan of Hebei Province, respectively. The DEM data are assessed using SRTM DEM, ICESat-GLAS points, and ground control points database obtained using ZY-3 satellite to validate the accuracy of DEM elevation. The experimental results show that the accuracy of DEM extracted from GF-3 satellite SAR data can meet the requirements of topographic mapping in mountain and alpine regions at the scale of 1 : 50000 in China. Besides, it proves that GF-3 satellite has the potential of interferometry.

scholarly journals GEOMETRIC CALIBRATION OF ZIYUAN-3 THREE-LINE CAMERAS COMBINING GROUND CONTROL POINTS AND LINES

2016 ◽  
Vol XLI-B1 ◽  
pp. 163-168
Author(s):  
Jinshan Cao ◽  
Xiuxiao Yuan ◽  
Jianya Gong
Keyword(s):  
Ground Control ◽  
Calibration Model ◽  
Control Points ◽  
Charge Coupled Device ◽  
Geometric Calibration ◽  
Ground Control Points ◽  
The Look ◽  
Ccd Detectors ◽  
True Values ◽  
Better Than

Due to the large biases between the laboratory-calibrated values of the orientation parameters and their in-orbit true values, the initial direct georeferencing accuracy of the Ziyuan-3 (ZY-3) three-line camera (TLC) images can only reach the kilometre level. In this paper, a point-based geometric calibration model of the ZY-3 TLCs is firstly established by using the collinearity constraint, and then a line-based geometric calibration model is established by using the coplanarity constraint. With the help of both the point-based and the line-based models, a feasible in-orbit geometric calibration approach for the ZY-3 TLCs combining ground control points (GCPs) and ground control lines (GCLs) is presented. Experimental results show that like GCPs, GCLs can also provide effective ground control information for the geometric calibration of the ZY-3 TLCs. The calibration accuracy of the look angles of charge-coupled device (CCD) detectors achieved by using the presented approach reached up to about 1.0''. After the geometric calibration, the direct georeferencing accuracy of the ZY-3 TLC images without ground controls was significantly improved from the kilometre level to better than 11 m in planimetry and 9 m in height. A more satisfactory georeferencing accuracy of better than 3.5 m in planimetry and 3.0 m in height was achieved after the block adjustment with four GCPs.

scholarly journals The Geometric Calibration and Validation for The ZY3-02 Satellite Optical Image

2017 ◽  
Vol XLII-1/W1 ◽  
pp. 587-593 ◽  
Author(s):  
X. Tang ◽  
X. Zhu
Keyword(s):  
Earth Observation ◽  
Ground Control ◽  
Control Points ◽  
Registration Accuracy ◽  
Positioning Accuracy ◽  
Geometric Calibration ◽  
Ground Control Points ◽  
System Errors ◽  
Better Than ◽  
Multispectral Camera

Chinese ZY3-02 satellite, which is the second of ZY3 series satellites, was launched in May 30th 2016 for complementing the mapping and earth observation. In order to eliminate various system errors of the platform and payload, the on-orbit geometric validation and calibration was carried out. Firstly, we introduced the parameters of the three-line stereo camera and multispectral camera bound on ZY3-02 in this paper. There are four optical cameras on ZY3-02: a 4-band nadir-looking multi-spectral camera with 5.8 m resolution, a 2.1m resolution nadir-looking panchromatic band camera, as well as 2.5m resolution forward- and backward-looking panchromatic band cameras. Compared with ZY3-01, the resolution of the forward- and backward-looking cameras on ZY3-02 were upgraded from 3.5 m to 2.5 m. Then we presented the methods and datasets used for calibration in details. After our calibration, the total positioning accuracy of the three-line camera images is better than 10m without ground control points (GCPs). The plane and height accuracy are improved to 3 and 2 m respectively, with few control points. The band-to-band registration accuracy of the multispectral camera is better than 0.15 pixels.

scholarly journals INVESTIGATING THE EFFECT OF PSO ALGORITHM ON REDUCING CONTROL POINTS IN CAMERA CALIBRATION

2019 ◽  
Vol XLII-4/W18 ◽  
pp. 363-369
Author(s):  
S. A. Fakhri ◽  
S. A. Fakhri
Keyword(s):  
Pso Algorithm ◽  
Control Points ◽  
Mathematical Methods ◽  
Accuracy Requirement ◽  
Ground Control Points ◽  
Lack Of Control ◽  
Complex Models ◽  
Correction Terms ◽  
Calibration Equations ◽  
Better Than

Abstract. Over the past decades, non-metric cameras have been utilized in functions with less accuracy requirement or even in precise works with the progress of photogrammetric cameras developed technology. One of the reasons to use these kinds of cameras is due very much to their lower costs in comparison with the metric ones. Since we have always error in measurements, there is no exception in Photogrammetry, which is more in the non-metric cameras than the metric ones. Some of these errors are systematic and the only way to cope with them is to model. So far, many models have been proposed to investigate and modify the behavior of errors. Some of these models are linear and some others are non-linear. The number of parameters in each model is different based on the complexity of error in each image. Since the picture need to be connected to earth to calculate the calibration parameters of the camera, therefore this connection is generally made through points known as the ground control points, and more of these control points are needed in the complex models with more sophisticated calculations. Using a method to reduce the need for less control points and achieving a suitable accuracy is beneficial due to the high cost and time-consuming process of preparing the control points. One of the methods that could be used in solving the calibration equations is the Particle Swarm Optimization (PSO) algorithm. Images of a few targets are captured in this research by a non-metric camera and the collinearity equations are used by adding further correction terms in order to calibrate the camera. The results of PSO method are compared with the classical mathematical methods in each step by reducing the number of control points, which indicated that the performance of using the PSO algorithm is better than the conventional proration methods in reducing the number of points and could be utilized in projects suffering from the lack of control points.

scholarly journals SNR of the coded aperture imaging system

2021 ◽  
Vol 28 (1) ◽  
pp. 106-112
Author(s):  
Jianwei Wang ◽  
Yan Zhao
Keyword(s):  
Image Quality ◽  
Imaging System ◽  
Reconstructed Image ◽  
Coded Aperture ◽  
Inverse Filtering ◽  
Light Emitting ◽  
Coded Aperture Imaging ◽  
Imaging Model ◽  
Better Than

AbstractIn this paper, the expression for the SNR has been developed through the imaging model. It is concluded that the image SNR decreases with the increase of the number of light-emitting points of the target under the same hardware conditions and experimental parameters. Using uniform bright squares of different sizes as the target, the SNR of the reconstructed image is calculated. Simulation and prototype experiments have proved the correctness of the conclusion. Based on this conclusion, a method of segmented area imaging is proposed to improve the reconstructed image quality. The quality of all the images using this method with Wiener inverse filtering, R-Lucy deconvolution, and ADMM is better than the image quality obtained by full-area imaging.

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