Synchronization monitoring atmospheric corrector (SMAC) sensor is equipped with polarization and intensity data, providing the possibility of retrieving more accurate aerosol parameters for main sensor's atmospheric correction. In this study, a novel aerosol retrieval algorithm based on intensity and polarization data was proposed. First, we analyze and construct the ratio relationship of different intensity and polarization channels of SMAC on different surface types and analyze the correlation between these ratios and normalized difference vegetation index (NDVI) and scattering angle (SCA). Then, for the first time, high-precision surface prior knowledge for SMAC aerosol retrieval is constructed, and then, intensity and polarization data were used to retrieve high-precision aerosol products simultaneously. These results are compared and validated with Moderate Resolution Imaging Spectroradiometer (MODIS) and ground-based observations aerosol products, and aerosol optical depth (AOD) product comparison between the SMAC and MODIS showed that they had similar spatial distribution, scattered dots of them with a Pearson correlation coefficient (R) of 0.84 and a root-mean-square error (RMSE) of 0.11. Meanwhile, their differences were also analyzed. The validation between the ground-based sites and the SAMC retrieval results also showed a good performance with R of 0.88 and RMSE of 0.10. These results revealed that the new algorithm is an effective method for retrieving reliable AOD products for the main sensor's atmosphere correction.

Multi-source hyperspectral data are increasingly applied in environmental monitoring, precision agriculture, and geological exploration, yet differences in sensor characteristics hinder interoperability. This study presents a systematic cross-validation of surface reflectance between the German EnMAP mission and the Chinese GF5-02 Advanced Hyperspectral Imager (AHSI) across four representative land cover types: minerals in the East Tianshan Mountains, tropical grasslands in Hainan Danzhou, desert in Dunhuang, and inland salt lakes in Qinghai. Using EnMAP Level-2A products as reference, we evaluated GF5-02 reflectance with spectral angle (SA), root mean squared error (RMSE), relative RMSE (RRMSE), and correlation coefficient (R). Results show strong consistency for high- and medium-reflectance surfaces (R > 0.96, SA < 0.08 rad), while water bodies exhibit larger discrepancies (R = 0.82, SA = 0.34 rad), likely due to atmospheric correction and sensor response differences. Additional ground validation in the East Tianshan region confirmed the reliability and stability of GF5-02 data. Overall, GF5-02 demonstrates high consistency with EnMAP across most land cover types, supporting quantitative applications, though further improvements are needed for low-reflectance environments.

The imaging process of Earth observation satellites is inevitably influenced by interference from atmospheric molecules and aerosols, which can impact both the qualitative and quantitative applications of satellite remote sensing imagery, such as land cover classification and ecological monitoring. Therefore, atmospheric correction (AC) is necessary to better utilize these satellite images. China has launched a variety of Earth observation satellites, such as the GaoFen series and the ZiYuan series, which provide multi-spectral, panchromatic, and hyperspectral imagery. However, achieving high-precision atmospheric correction for these images remains a significant challenge. This study develops an atmospheric correction method based on radiative transfer model, suitable for the visible to shortwave infrared spectrum of Chinese high-resolution remote sensing imagery. Using GF-2 multi-spectral and panchromatic data as examples, the study analyzes and evaluates the AC results. A comparative analysis of the data before and after AC shows that the proposed method is highly effective and accurate.

The geographic information resources are the important basic and strategic information resources, which can play an indispensable role in the process of information construction. At present, under the background of national major project of global mapping, the control points of new supplementary image are selected by using the original block adjustment results to carry out the large-scale block adjustment. However, because the large-time span, uneven geometric accuracy, archiving results are not easy to find and other problems. Therefore, in the absence of overseas GCPs, a combined block adjustment scheme of multi-source satellite image based on the existing DOM and DSM is proposed in this paper, in order to not change the previous results and adapt to the urgent needs of good edge matching with the historical loopholes. The results show that the scheme is feasible and can improve the positioning accuracy of edge matching, which provides a significant reference for the production of subsequent global surveying tasks.

Real 3D in China construction is oriented to the new positioning and new demand of surveying, mapping and geographic information service for economic and social development and ecological civilization construction in the new era. The GF-7 satellite is China's first sub-meter high-resolution optical transmission stereo surveying and mapping satellite, designed to meet the requirements of 1:10 000 scale surveying and mapping. However, there did not exist a comprehensive method to verify the accuracy of block adjustment results for GF-7 satellite stereo images. In this paper, 46 pairs of GF-7 stereo images distributed in Jiangsu, China, were used to carry out block adjustment with high-precise GCP, and a comprehensive accuracy evaluation method was used to verify the adjustment results. The experimental results show that: the comprehensive accuracy verification method can accurately and efficiently check the accuracy of GF-7 stereo images, provide good data support for subsequent data processing and analysis.

资源三号03星是自然资源部主持建造的用于1 ∶ 50000立体测图的陆地遥感业务卫星,该星装备了业务化的激光测高仪,主要用于获取高精度高程控制点.论文针对资源三号03星激光测高数据,研究了标准化测绘处理流程和高程控制点提取方法,在内蒙古苏尼特右旗和江苏苏州开展了精度验证,并选择黑龙江和河北两个实验区开展了复合测绘应用验证.精度验证结果表明,资源三号03星激光点在内蒙古苏尼特右旗平坦区域高程精度为(0.051±0.232)m,在江苏苏州城市建成区的激光点总体精度为(0.414±6.213)m,经高程控制点提取和质量标记后的激光点高程误差为(-0.526±0.624)m,能满足1 ∶ 50 000测图高程控制需求.复合测绘应用表明,利用资源三号03星激光高程控制点,立体影像高程精度在黑龙江平坦地区能从5.27 m提高到2.58 m,河北太行山区能从11.25 m提高到4.45 m;无论是平地还是山区,资源三号03星激光高程控制点均能有效提高立体影像的高程精度并满足1 ∶ 50 000测图需求.

ZY-1 02D satellite is an important satellite in China space infrastructure planning. The Land Satellite Remote Sensing Application Center of the Ministry of Natural Resources of the People’s Republic of China (LASAC) undertook the construction of the satellite hyperspectral data processing system and produced surface reflectance products. Reflectance is the basis of hyperspectral remote sensing data application, which is directly related to the efficiency and quality of hyperspectral application. At present, there is no comprehensive and in-depth study on the accuracy evaluation of the atmospheric correction reflectance of ZY1 - 02D satellite hyperspectral data. In view of this problem, Accuracy Verification of LASAC products using accuracy, precision, uncertainty, spectral curve correlation and spectral angle chord four indicators based on surface reflectance produced by AERONET ground measured data. The results show that the average values of accuracy, precision, uncertainty of LASAC products are 3.2 %, 2.02 % and 4.13 %, respectively. The spectral curve correlation and spectral chord angle are 0.998 and 0.979, respectively. The research result can provide technical reference for the processing and application of ZY1 - 02D hyperspectral image surface reflectance products.

Improving the accuracy of block adjustment with few or no ground control points (GCPs) is one of the core issues for satellite imagery high-precision mapping. The GaoFen-7 (GF-7) satellite laser altimeter system is the first Chinese formal spaceborne laser altimeter system, which is equipped with laser footprint cameras for the first time. Given the very high height accuracy and high planimetric accuracy of the instrument, this letter proposed an adjustment method of ZiYuan-3 (ZY-3) satellite imagery by integrating GF-7 laser altimetry data. The laser control points (LCPs) were automatically extracted according to the registration of the footprint images and stereo images. Furthermore, the combined adjustment was performed with the LCPs as the vertical control and horizontal constraint. The performance of the proposed method was evaluated by using 417 stereo scenes of ZY-3 images and 954 LCPs, covering an area of 158 000 km 2 in Shandong, China. The results demonstrated that, only by using all LCPs as the vertical control, the root mean square error (RMSE) of elevation can be significantly improved from the original 8.82 to 1.40 m. Moreover, the planimetric RMSE decreased from the original 15.31 to 3.58 m with residual randomness when 45 LCPs were used as the horizontal constraint. Our method provides an alternative solution for satellite imagery geopositioning improvement without GCPs.

Globalized surface coverage, environmental monitoring and other earth system science and high-quality global surface coverage monitoring applications urgently need basic hyperspectral remote sensing reflectance data to support. Spectral reflectance is the core data product of hyperspectral satellite remote sensing data, which is directly related to the application efficiency and quality of hyperspectral satellite. Due to the differences in spectral range, resolution width, central wavelength and other factors between multispectral and hyperspectral remote sensing images, the fusion processing of hyperspectral and multispectral remote sensing images is extremely difficult. In this study, the idea of normalization of physical parameters is adopted. Based on the remote sensing data of multi-source satellites such as GF5, GF1WFV and ZY3, the physical parameters of GF series satellites are fused to improve the spatial resolution of hyperspectral remote sensing images while the physical parameters of surface parameters are maintained. According to the fusion quality evaluation results of noise, information entropy, clarity, spectral angle cosine, correlation coefficient and root mean square error, the fusion results are consistent with the original numerical performance. The noise level, information entropy and clarity index of GF5 and ZY3 fusion are better. The spectral angle cosine, correlation coefficient and root mean square error index of GF5 and GF1 fusion are better. This study provides a new way and method for high-precision and quantitative processing of hyperspectral remote sensing data.

GaoFen 7 (GF-7) is China’s first submeter high-resolution stereo mapping satellite with dual-linear-array cameras and a laser altimeter system onboard for high-precision mapping. To further take advantage of the very high elevation accuracy of laser altimetry data and the high relative accuracy with stereo images, an innovative combined adjustment method for GF-7 stereo images with laser altimetry data is presented in this paper. In this method, two flexible and effective schemes were proposed to extract the elevation control point according to the registration of footprint images and stereo images and then utilized as vertical control in the block adjustment to improve the elevation accuracy without ground control points (GCPs). The validation experiments were conducted in Shandong, China, with different terrains. The results demonstrated that, after using the laser altimetry data, the root mean square error (RMSE) of elevation was dramatically improved from the original 2.15 m to 0.75 m, while the maximum elevation error was less than 1.6 m. Moreover, by integrating a few horizontal control points, the planar and elevation accuracy can be simultaneously improved. The results show that the method will be useful for reducing the need for field survey work and improving mapping efficiency.

The Ziyuan3-03 (ZY3-03) satellite is an optical stereo mapping satellite that is able to synchronously provide triple linear-array stereo images and discrete laser altimetry points (LAPs) for plotting 1:50 000-scale maps. Considering that the relative horizontal error between the ZY3-03 nadir image and synchronously acquired LAPs is very small, this study designed a technical method to obtain accurate image coordinates of LAPs on stereo images, and this method successfully overcomes the shortcomings of previous methods. Subsequently, a combined block adjustment model of stereo images and LAPs was constructed. On this basis, this study proposed a combined block adjustment method using ZY3-03 stereo images and LAPs to improve the vertical accuracy of images. For our research, 19 ZY3-03 triple linear-array stereo images and 87 synchronously acquired LAPs of plain, hilly, and mountainous terrains located in China were selected to conduct the block adjustment experiment. Results indicated that the vertical root-mean-square error of the experimental images decreased from 5.27 to 2.58 m for plain and hilly terrains and decreased from 11.25 to 4.45 m for mountainous terrain. Moreover, the vertical accuracy of the experimental images met the requirement of 1:50 000-scale mapping and also exceeded the accuracy of combined adjustment with Ice, Cloud, and land Elevation Satellite (ICESat)-1 satellite LAPs and the same experimental images.

- The China's high-resolution remote sensing satellite was used as the significant data source for global 1:50000 scale surveying and mapping 4D product generation, However, due to the serious lack of high-precise control data for overseas region, there exist problem that the geometric accuracy of satellite image cannot be guaranteed, and an improved approach using the integrating of public geographic information data was proposed in this paper to enhance the geometric accuracy of satellite image without the GCPs. 870 pairs of ZY3, 36 pairs of GF and 371 pairs of TH satellite image were acquired in the experimental region of eastern part of Europe, 25 high-precise outdoor surveying GCPs were used for the accuracy verification of block adjustment result for ZY3, GF and TH series image generated by the proposed approach in this paper. The experimental results showed that the block adjustment conducted by the proposed approach in this paper can meet the horizontal and vertical accuracy requirement of global 1:50000 surveying and mapping in China. Moreover, a standard overseas basic surveying and mapping product generation approach of stereo image was proposed in this article, 2141 sheets of DOM, DSM, DEM and DLG data based on the proposed approach in this paper were generated, respectively, and the final examination conclusion of quality was “batch qualified”. The experimental areas and images selected in this paper were large and representative, the improved global 1:50000 surveying and mapping 4D product generation approach using the public geographic information data recommended in this paper can be used as a significant approach when generating global 1:50000 scale surveying and mapping 4D products.

DSM is one of the important component of basic geographic information digital product which mainly acquired by the optical stereo image photogrammetry and SAR data interferometry, however, the interferometric strips of high-resolution SAR data was dense and very difficult to unwrap. In order to solve this problem, an improved phase unwrapping approach using the high-precise 1:10000 scale surveying and mapping optical DSM data was proposed in this paper. 13 pairs of SLC data for TanDEM-X image covering the eastern part of Xi'an region were selected as the experimental image, and SRTM30 and 1:10000 high-precise optical DSM data distributed in this experimental region were collected as reference data. Moreover, a total of 393 outdoor surveying GCPs were used as check points to examine the accuracy of DSM generated by the traditional and improved SAR-DSM generation approach. In general, the RMSE of improved and traditional SAR-DSM generation approach was 7.19m and 9.31m, respectively. By the vertical accuracy examination of check points, for the improved and traditional SAR-DSM generation approach, the ratio of vertical error of 0-3m was 50.89% and 48.85%, the ratio of 3-5m was 13.23% and 15.01%, the ratio of 5-8m was 16.79% and 16.54%, the ratio of 8-14m was 11.71% and 13.49%, and the ratio of more than 14m was 7.89 % and 5.6%, respectively. It can be seen from the comparison that the result of improved SAR-DSM generation approach was better than the traditional approach. Because the experimental areas and experimental images selected in this paper were large and representative, the improved SAR-DSM generation approach using the high-precise 1:10000 scale surveying and mapping optical DSM recommended in this paper can be used as a new method when generating DSM using the SAR interferometry technology.

An important and difficult point in the application of satellite imagery is refining the positioning model and improving the geometric accuracy. In this study, we focus on improvement in geometric accuracy and develop a new rational function model (RFM) refinement method. First, we derive the conversion relationship between the rigorous sensor model and the RFM, based on which we illustrate the approximate meaning of the zero-order and first-order terms of the rational polynomial coefficients (RPCs). Second, the correlation problem between RPCs and the influence of individual RPCs on geometric positioning accuracy are analyzed and verified. The dominant coefficients that determine geolocation are then identified. Finally, a new RFM refinement method based on direct correction of the dominant coefficients is proposed and validated. The experiments, conducted with ZY3-02 satellite imagery, indicate that the proposed method can effectively improve the geometric accuracy of satellite images.

The integrating of ZY3 and GF3 satellite image can achieved long-term acquisition of DOM product, however, the selection of point in SAR image was a difficult task, and the edge error cannot be guaranteed if the optical and SAR images were produced individually, an improved DOM product generation approach was proposed in order to ensure the accuracy and efficiency of DOM generation. 29 scenes of ZY3 image and 20 scenes of GF3 image in Hainan island were selected as experimental image, and the results showed that the horizontal accuracy of 73.47% of orthorectification result were better than 1 pixel (10 m), and 26.53% of orthorectification result were better than 2 pixels (20 m), which can meet the horizontal accuracy requirement of 1:50000 scale surveying and mapping in China. At the same time, an improved approach using the dodging and mosaic line editing was proposed to integrate the orthrectification image, it can be seen from this article that the color transition of ZY3 data region and the hue transition of GF3 data region was more natural, and the manual editing was not big. Therefore, the efficiency and accuracy of the improved approach of DOM generation proposed in this paper can be guaranteed in large areas, which can be used as a reference for users when generating the DOM using the integrating image of ZY3 and GF3.

The successful launch of GF3 satellite has achieved long-term, sustained and stable acquisition of DOM product all over the China, however, it is a difficult project to deploy angle transmitter or select the same image points between SAR image and optical image manually, which only suitable for SAR image in some small areas, and cannot meet the needs of production and engineering application in large areas. In order to reduce the cost and improve the efficiency of surveying and mapping, a new approach of DOM product generation in large areas was proposed in this paper, which can automatically achieve the process of heterogeneous data matching of SAR data based on the optical DOM reference map and the process of dodging and mosaic line editing. 100 scenes of SLC image of GF3 satellite with the FSII imaging mode covering a large area and Beijing-Tianjin-Hebei region were selected as experimental image, by the heterogeneous data matching, high-precise control points and link points were automatically acquired, and the block adjustment of GF3 data in the experimental area was completed. The RMSE of all control points and link points in azimuth direction was better than 0.41 pixels, the RMSE in range direction was better than 0.85 pixels, and the maximum error was better than 3 pixels. According to the requirement of quality examination, based on the ZY3-DOM data, 5 checkpoints were well-distributed selected for each scene of image. The experimental results showed that the horizontal accuracy of 66% of image orthorectification result were better than 1 pixel (10 m), and 34% of image orthorectification result were better than 2 pixels (20 m), in which the accuracy between 10 and 20 meters were mountain or high-mountain terrain. And the GF3 orthorectification result can meet the horizontal accuracy requirement of 1:50000 scale surveying and mapping in China. At the same time, for the orthorectification result of 100 scenes of GF3 data, dodging and mosaic line were automatically generated and processed, and appropriate dodging points were added to adjust the grey value of one or both sides of image. It can be seen from this article that the hue transition of whole experimental area was more natural, there was no obvious hue difference, and the amount of manual editing was not big. Therefore, the degree of automation of this approach proposed in this paper was very high, which can meet the needs of dodging process in large areas of GF3 data.

Due to the influence of the external environment, the satellite's surface is often irregularly folded, and these folds have some influences on the optical properties. So folds need to be taken into account in the modeling of the optical characteristics of space objects. However, a large number of surface cells in fold surface will lead to a dramatic increase in computational complexity. This paper considers pleats as a kind of 'material'. A method based on macroscopic optical scattering cross section measurement is proposed to obtain the bidirectional reflectance distribution function (BRDF) data of the fold material. Furthermore, the error back propagation neural network is used to establish BRDF model of fold material, which replaces the complex modeling process of folds and greatly simplifies the calculation. The problem of poor real-time performance is solved under the acceptable accuracy. By combining the experiment with the simulation to compare the BRDF model designed in this paper with the traditional BRDF model, it is verified that the error of the model designed in this paper is much smaller than that of the traditional model.

This paper proposes a stereo-image block-adjustment algorithm without ground control points (GCPs) by adopting a Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) as a height assistant. Using dense, evenly distributed tie points on images used in the block adjustment, the initial height values of tie points are derived directly from the SRTM DEM. In the subsequent block-adjustment iterative computation, the height correction value for tie points is rigorously restricted by the SRTM DEM elevation. A total of 509 ZY-3 satellite stereo-images across 190000km(2) of China's Hubei Province were used for this block-adjustment experiment. The results show that the vertical root mean square errors (RMSEs) are improved from 72 to 23m without GCPs, while the RMSEs in flat and mountainous terrain are improved to 15 and 28m, respectively, fulfilling the vertical accuracy requirement of China's 1:25000 scale mapping. Resume Cet article propose un algorithme d'ajustement par blocs sans points d'appui pour des images stereoscopiques, utilisant le MNT SRTM (Shuttle Radar Topography Mission) comme donnee altimetrique auxiliaire. A partir d'un semis dense et irregulier de points d'appui dans les images utilisees pour le calage, les valeurs altimetriques des points d'appui sont obtenues directement a partir de SRTM. Lors du calcul des iterations suivantes, la correction altimetrique des points d'appui est rigoureusement contrainte par les altitudes de SRTM. Des images stereoscopiques du satellite 509 ZY-3 couvrant une zone de 190000km(2) dans la province chinoise de Hubei ont ete utilisees pour cette experience d'ajustement par blocs. Les resultats montrent que les ecarts moyens quadratiques (EMQ) verticaux sont ameliores de 7,2 a 2,3m sans points d'appui, tandis que les EMQ sur terrain plat et montagneux sont ameliores pour atteindre respectivement 1,5 et 2,8m, ce qui permet de satisfaire les exigences de precision de la cartographie au 1:25000 de la Chine. Zusammenfassung In diesem Beitrag wird eine Blockausgleichung fur Stereobildpaare ohne den Einsatz von Passpunkten aber unter Zuhilfenahme eines Hohenmodells (DEM) der Shuttle Radar Topography Mission (SRTM) vorgestellt. Es werden gleichma ss ig verteilte Verknupfungspunkte fur die Blockausgleichung ausgewahlt und die initialen Hohenwerte dieser Verknupfungspunkte direkt aus dem SRTM DEM entnommen. In den iterativen Berechnungen der nachfolgenden Blockausgleichung wird die Hohenkorrektur der Verknupfungspunkte durch die SRTM DEM Hohe streng eingeschrankt. Es wurden 509 Stereobilder des ZY-3 Satelliten uber 190000km(2) der Provinz Hubei in China fur diese Untersuchung eingesetzt. Die Ergebnisse zeigen, dass die mittleren quadratischen Fehler (RMSEs) in der Hohe von 72 auf 23m ohne GCPs verbessert werden, wahrend die RMSEs in flachen bzw. bergigem Gelande auf 15 bzw. 28m verbessert werden, und somit die Anforderungen fur chinesische Kartenwerke im Ma ss stab 1:25000 erfullen. Resumen En este articulo se propone un algoritmo de ajuste de bloques de imagenes estereoscopicas sin puntos de apoyo (PA) usando el modelo de elevacion digital (MED) del Shuttle Radar Topography Mission (SRTM) como control/restriccion en altura. En el ajuste de bloques se usan puntos de enlace uniformemente distribuidos en las imagenes, los valores de altura inicial de los puntos de enlace se derivan directamente del MED SRTM. En las siguientes iteraciones del ajuste de bloque, el valor de correccion de altura para los puntos esta rigurosamente restringido por la altura del MED SRTM. En este experimento de ajuste de bloques se han utilizado 509 imagenes estereoscopicas de satelite ZY-3 cubriendo 190000km(2) de la provincia china de Hubei. Los resultados muestran que el RMS del error se mejora de 7,2 a 2,3m sin PA, mientras que el RMS del error en terreno plano y montanoso se mejora en 1,5 y 2,8m respectivamente, satisfaciendo los requisitos en China para la cartografia a escala 1:25000.

资源三号02星(ZY-3 02)作为资源三号系列的第2颗卫星,于2016年5月30号成功发射,其主要服务于中国空间基础建设等重大工程,星上搭载了中国首个对地观测试验性激光测高载荷.高程精度作为立体测图的重要指标,达到其精度要求的困难程度远大于平面.在借鉴目前较成熟的卫星影像区域网平差理论的基础上,结合近年来激光测高数据精度的大幅提升以及ZY-3 02星激光测高数据的特点,首次提出了激光测高数据辅助卫星立体影像进行成像几何模型精化处理的通用理论.首先,利用传统的区域网平差算法对所处理影像进行高精度连接点匹配处理,并对其进行无约束的自由网平差处理,获得高精度相对精度及不亚于原始成像几何模型的绝对精度;其次,根据激光测高数据3维坐标和精化后参考影像成像几何模型获取激光数据参考影像坐标;然后,将参考影像坐标通过几何模型映射获取目标影像上待匹配影像坐标,通过连接点匹配算法,对待匹配目标影像坐标进行精化获取高精度像方同名点;最后,以同名点作为高程控制进行区域网平差计算,对影像成像几何模型进一步处理,获取高精度补偿参数.通过湖北、青海两测区的试验,以激光测高数据辅助卫星影像几何模型精化精度可分别达到1.97 m、3.23 m,结果表明本文提出的方法可有效提高卫星立体数据测图精度.