Measurement of Coordinate Parameter by Multi-baseline Digital Close-range Photogrammetry System and Data Analysis for Jujube

[Objective] The aim was to explore the measurement of coordinate parameter by multi-baseline digital close-range photogrammetry system.[Method] The 3-dimensional coordinate of 8-year-old Jujube was measured by using Lensphoto multi-baseline digital close-range photogrammetry system,and through comparing with measured data of Total Station,the error and accuracy of photogrammetry data were analyzed.[Result] The absolute error of X,Y and Z coordinate was 0-0.014,0-0.018 and 0-0.004 m respectively,and the relative error of X,Y and Z coordinate was less than 0.145%.The significance test of pairs for the photogrammetry data and measured data of Total Station indicated that the space coordinate data of stumpage were accurately measured by using the multi-baseline digital close-range photogrammetry method,and the photogrammetry data meet the need of space coordinate measurement for virtual plant growth simulation.[Conclusion] This study had provided theoretical basis for the growth measurement of virtual plant growth simulation.

Determination Method for Shear Strength Parameters of Rock-Soil Mixtures Using Close-Range Photogrammetry and 3-D Limit Equilibrium Theory

Using a combination of close-range photogrammetry and three-dimensional(3-D) limit equilibrium theory, a determination method for the shear strength parameters of rock-soil mixture is presented. A close-range photogrammetry method is used for measurement of the 3-D terrain of the experimental target. Auto CAD Lisp and EXCEL VBA are used to perform 3-D limit equilibrium analysis of the stability of sliding mass and perform backanalysis of shear strength parameters. The presented method was used to determine the shear strength parameters of rock-soil mixtures at the Liyuan Hydropower Station. The 3-D terrain of sliding surface could be measured notably well using of closerange photogrammetry. The computed results reveal that the cohesion and friction angle of rock-soil mixtures were 3.15 k Pa and 29.88o for test A, respectively, and 4.43 k Pa and 28.30o for test B, respectively, within the range of shear strength parameters, as determined by field and laboratory tests. The computation of shear strength parameters is influenced by the mesh grid number, especially the cohesion of the rock-soil mixture. The application of close-range photogrammetry can reduce the siteworks and improve the computational efficiency and accuracy.

Direct Creation of Construction Drawings for Kwan-yin Statue by Close-Range Photogrammetry

In order to provide the model point accuracy of ±2 mm,an extra high accuracy industrial control net with four surveying piers with accuracy ±0.1 mm was set up around the model.Tens of orientation marks have been placed on the different parts and measured with accuracy ±0.2 mm from the above_mentioned piers.The main four stereopairs taken with the P31 camera around the model are simultaneously processed on the BC2 analytical plotter.The accuracy of absolute orientation is better than ±0.9 mm.Finally,about 300 sections construction drawings have been directly offered,and the close_range photogrammetric data has been used for the design and construction of the statue.

Characteristics and close-range exploration methods of near- Earth asteroid 2016HO_(3)

The characteristics of asteroids are vital parameters for planning asteroid exploration missions.These characteristics have been explored in close range for some typical asteroids,and are summarized in the article.This allows estimates of the characteristics of asteroid 2016HO_(3),the target of the first Chinese asteroid exploration mission,Tianwen 2.We obtain 80 characteristic parameters in 9 categories and analyze their impacts on the mission.By comparing three close-range exploration modes,we provide advantages and disadvantages of each,and propose suitable methods for the exploration of 2016HO_(3).Owing to the weak gravity and small size of 2016HO_(3),a combination of multiple hovering positions and active orbiting is recommended for scientific exploration.

Urban Geospatial Information Acquisition Mobile Mapping System based on close-range photogrammetry and IGS site calibration

The measurement accuracy of the Mobile Mapping System (MMS) is the main problem, which restricts its development and application, so how to calibrate the MMS to improve its measure-ment accuracy has always been a research hotspot in the industry. This paper proposes a position and attitude calibration method with error correction based on the combination of the feature point and feature surface. First, the initial value of the spatial position relation-ship between each sensor of MMS is obtained by close-range photogrammetry. Second, the optimal solution for error correction is calculated by feature points in global coordinates jointly measured with International GNSS Service (IGS) stations. Then, the final transformation para-meters are solved by combining the initial values obtained originally, thereby realizing the rapid calibration of the MMS. Finally, it analyzed the RMSE of MMS point cloud after calibration, and the results demonstrate the feasibility of the calibration approach proposed by this method. Under the condition of a single measurement sensor accuracy is low, the plane and elevation absolute accuracy of the point cloud after calibration can reach 0.043 m and 0.072 m, respectively, and the relative accuracy is smaller than 0.02 m. It meets the precision require-ments of data acquisition for MMS. It is of great significance for promoting the development of MMS technology and the application of some novel techniques in the future, such as auton-omous driving, digital twin city, urban brain et al.

A method to interpret fracture aperture of rock slope using adaptive shape and unmanned aerial vehicle multi-angle nap-of-the-object photogrammetry

The aperture of natural rock fractures significantly affects the deformation and strength properties of rock masses,as well as the hydrodynamic properties of fractured rock masses.The conventional measurement methods are inadequate for collecting data on high-steep rock slopes in complex mountainous regions.This study establishes a high-resolution three-dimensional model of a rock slope using unmanned aerial vehicle(UAV)multi-angle nap-of-the-object photogrammetry to obtain edge feature points of fractures.Fracture opening morphology is characterized using coordinate projection and transformation.Fracture central axis is determined using vertical measuring lines,allowing for the interpretation of aperture of adaptive fracture shape.The feasibility and reliability of the new method are verified at a construction site of a railway in southeast Tibet,China.The study shows that the fracture aperture has a significant interval effect and size effect.The optimal sampling length for fractures is approximately 0.5e1 m,and the optimal aperture interpretation results can be achieved when the measuring line spacing is 1%of the sampling length.Tensile fractures in the study area generally have larger apertures than shear fractures,and their tendency to increase with slope height is also greater than that of shear fractures.The aperture of tensile fractures is generally positively correlated with their trace length,while the correlation between the aperture of shear fractures and their trace length appears to be weak.Fractures of different orientations exhibit certain differences in their distribution of aperture,but generally follow the forms of normal,log-normal,and gamma distributions.This study provides essential data support for rock and slope stability evaluation,which is of significant practical importance.

High-resolution photogrammetry to measure physical aperture of two separated rock fracture surfaces

Photogrammetry,reconstructing three-dimensional(3D)models from overlapping two-dimensional(2D)photos,finds application in rock mechanics and rock engineering to extract geometrical details of reconstructed objects,for example rock fractures.Fracture properties are important for determining the mechanical stability,permeability,strength,and shear behavior of the rock mass.Photogrammetry can be used to reconstruct detailed 3D models of two separated rock fracture surfaces to characterize fracture roughness and physical aperture,which controls the fluid flow,hydromechanical and shear behavior of the rock mass.This research aimed to determine the optimal number of scale bars required to produce high-precision 3D models of a fracture surface.A workflow has been developed to define the physical aperture of a fracture using photogrammetry.Three blocks of Kuru granite(25 cm×25 cm×10 cm)with an artificially induced fracture,were investigated.For scaling 3D models,321 markers were used as ground control points(GCPs)with predefined distances on each block.When the samples were wellmatched in their original positions,the entire block was photographed.Coordinate data of the GCPs were extracted from the 3D model of the blocks.Each half was surveyed separately and georeferenced by GCPs and merged into the same coordinate system.Two fracture surfaces were extracted from the 3D models and the vertical distance between the two surfaces was digitally calculated as physical aperture.Accuracy assessment of the photogrammetric reconstruction showed a 20-30 mm digital control distance accuracy when compared to known distances defined between markers.To attain this accuracy,the study found that at least 200 scale bars were required.Furthermore,photogrammetry was employed to measure changes in aperture under normal stresses.The results obtained from this approach were found to be in good agreement with those obtained using linear variable displacement transducers(LVDTs),with differences ranging from 1 mm to 8μm.

A photogrammetric approach for quantifying the evolution of rock joint void geometry under varying contact states

Accurate measurement of the evolution of rock joint void geometry is essential for comprehending the distribution characteristics of asperities responsible for shear and seepage behaviors.However,existing techniques often require specialized equipment and skilled operators,posing practical challenges.In this study,a cost-effective photogrammetric approach is proposed.Particularly,local coordinate systems are established to facilitate the alignment and precise quantification of the relative position between two halves of a rock joint.Push/pull tests are conducted on rock joints with varying roughness levels to induce different contact states.A high-precision laser scanner serves as a benchmark for evaluating the photogrammetry method.Despite certain deviations exist,the measured evolution of void geometry is generally consistent with the qualitative findings of previous studies.The photogrammetric measurements yield comparable accuracy to laser scanning,with maximum errors of 13.2%for aperture and 14.4%for void volume.Most joint matching coefficient(JMC)measurement errors are below 20%.Larger measurement errors occur primarily in highly mismatched rock joints with JMC values below 0.2,but even in cases where measurement errors exceed 80%,the maximum JMC error is only 0.0434.Thus,the proposed photogrammetric approach holds promise for widespread application in void geometry measurements in rock joints.

Three-dimensional finite element simulation and reconstruction of jointed rock models using CT scanning and photogrammetry

The geometry of joints has a significant influence on the mechanical properties of rocks.To simplify the curved joint shapes in rocks,the joint shape is usually treated as straight lines or planes in most laboratory experiments and numerical simulations.In this study,the computerized tomography (CT) scanning and photogrammetry were employed to obtain the internal and surface joint structures of a limestone sample,respectively.To describe the joint geometry,the edge detection algorithms and a three-dimensional (3D) matrix mapping method were applied to reconstruct CT-based and photogrammetry-based jointed rock models.For comparison tests,the numerical uniaxial compression tests were conducted on an intact rock sample and a sample with a joint simplified to a plane using the parallel computing method.The results indicate that the mechanical characteristics and failure process of jointed rocks are significantly affected by the geometry of joints.The presence of joints reduces the uniaxial compressive strength (UCS),elastic modulus,and released acoustic emission (AE) energy of rocks by 37%–67%,21%–24%,and 52%–90%,respectively.Compared to the simplified joint sample,the proposed photogrammetry-based numerical model makes the most of the limited geometry information of joints.The UCS,accumulative released AE energy,and elastic modulus of the photogrammetry-based sample were found to be very close to those of the CT-based sample.The UCS value of the simplified joint sample (i.e.38.5 MPa) is much lower than that of the CT-based sample (i.e.72.3 MPa).Additionally,the accumulative released AE energy observed in the simplified joint sample is 3.899 times lower than that observed in the CT-based sample.CT scanning provides a reliable means to visualize the joints in rocks,which can be used to verify the reliability of photogrammetry techniques.The application of the photogrammetry-based sample enables detailed analysis for estimating the mechanical properties of jointed rocks.

Digital close-range photogrammetric application to small-scale physical simulation experiment

In order to research the possibility of digital close-range photogrammetric surveying in small scale physical simulation experiment, physical model coinciding with engineering practice was constructed based on similar theory. The datum processing method and surveying precision of digital close-range photogrammetric were analyzed. And the function relationship between overburden subsidence factor qr and the ratio z/H of stratum horizon z and mining depth H was researched. The results show that surveying points position mean error along horizontal direction is ±0.131 mm and vertical direction is ±0.192 mm. Therefore, multi-taking station cross direction digital close-range photogrammetric can completely satisfy the precision need of physical simulation experiment. And the empirical formula can be utilized to represent evolution law of stratum subsidence factor.

摄影测量与遥感领域主题演化研究——以《ISPRS Journal of Photogrammetry and Remote Sensing》期刊为例

为了便于相关领域的研究人员了解遥感学领域的整体发展状态并进行量化分析,本文以国际摄影测量与遥感学会(ISPRS)官方刊物作为研究数据,从主题挖掘和主题关联的角度出发,在计量分析的基础上,基于隐含狄利克雷分布(LDA)和word2vec的主题演化模型进行分析与研究,重点解决了摄影测量与遥感学领域主题挖掘、学科领域主题关联、学科主题演化建模和主题演化知识图谱等问题,展示了遥感学领域的主题动态演化过程。主题演化研究结果表明:1)主题强度总排名前三的主题分别是激光扫描技术、摄影测量、遥感信息提取与分类;2)随着深度学习的深入发展,遥感学领域的深度学习相关应用研究热度逐渐攀升;3)环境遥感相关方向的研究热度相对稳定,演化关系多局限于相关研究内部。

A Comparative Experimental Study on the Blast-Resistant Performances of Single and Multi-Layered Thin Plates Under Close-Range Airblast Loading

The performance of multilayered thin steel plates subjected to close-range air blasts has been experimentally studied and compared with that of monolithic plates made of the same material and having equal mass. In present experiments, multilayered plates are in-contact four-layered thin steel plates and two types of deformation/failure modes were observed for them. Comparisons concerning deformation/failure modes, strain distributions and energy absorptions between the multilayered plate and its monolithic counterpart were conducted. It is found that the multilayered plate is much superior to its monolithic counterpart in the ability to deform against blast loading. Furthermore, under intense airblast loading, the multilayered plate can not only absorb much more energy but also effectively reduce the secondary destruction ability of structural fragments in comparison with its monolithic counterpart.

Architectural Model of a Dryland Gravel Braided River,based on 3D UAV Oblique Photogrammetric Data:A Case Study of West Dalongkou River in Eastern Xinjiang,China

Three-dimensional unmanned aerial vehicle(UAV)oblique photogrammetric data were used to infer mountainous gravel braided river lithofacies,lithofacies associations and architectural elements.Hierarchical architecture and lithofacies associations with detailed lithofacies characterizations were comprehensively described to document the architectural model,architectural element scale and gravel particle scale.(1)Nine lithofacies(i.e.,Gmm,Gcm,Gcc,Gci,Gcl,Ss,Sm,Fsm and Fl)were identified and classified as gravel,sand and fine matrix deposits.These are typical depositional features of a mountainous dryland gravel-braided river.(2)Three architectural elements were identified,including channel(CH),gravel bar(GB)and overbank(OB).CH can be further divided into flow channel and abandoned channel,while GB consists of Central Gravel bar(CGB)and Margin Gravel bar(MGB).(3)The gravel bar is the key architectural element of the gravel braided river,with its geological attributes.The dimensions of GBs and their particles are various,but exhibit good relationships with each other.The grain size of GB decreases downstream,but the dimensions of GB do not.The bank erosion affects the GB dimensions,whereas channel incision and water flow velocity influence the grain size of GB.The conclusions can be applied to the dryland gravel braided river studies in tectonically active areas.

基于无人机摄影测量的建筑表皮光伏设计与效益评估

在建筑表皮部署光伏(PV)是有前途的策略,可以使建筑生产可再生能源并实现社会的碳中和目标。当前缺乏用于光伏建筑集成设计和效益评估的建筑精细化实景建模方法,难以对光伏的产能和视觉效果进行详细分析,形成合理方案。以无人机倾斜摄影测量技术为基础,结合参数化分析和美学设计方法,探索出用于建筑表皮光伏设计和效益评估的整体性方法。对天津市一教育性建筑进行了案例研究,得到了优化的光伏组件部署方案和产能潜力评估结果。为今后更多建筑的屋顶、立面光伏设计提供理论依据和方法借鉴。

无人机倾斜摄影测量在采空塌陷区生态综合治理中的应用

针对郭家湾煤矿51101工作面采空塌陷区生态综合治理问题,利用无人机搭载五镜头倾斜相机获取航摄影像,经过内业处理、三维建模获得实景三维模型。通过对像控点和三维模型精度分析,证明无人机倾斜摄影测量完全满足煤矿治理大比例尺地形图测图要求。依托实景三维模型和生成的高精度DLG数据成果,可帮助设计人员准确高效地提出相应采空塌陷区生态治理方式,大大提高了塌陷治理以及土地复垦工作的针对性和工作效率,为后期项目验收提供了准确可信的技术支撑和成果验证,最终有效解决了治理区地表变形和生态破坏问题。

基于无人机倾斜摄影测量三维建模的区域黄土滑坡识别及特征分析

【研究目的】黄土滑坡是黄土地区人居与城镇建设安全的重大隐患。滑坡识别是滑坡灾害及其他研究工作的基础,因此基于无人机倾斜摄影测量三维建模从不同维度、不同视角直观快速地识别黄土滑坡并进行特征参数提取,能够为黄土滑坡风险识别及风险管理精细化研究提供技术支撑。【研究方法】以宁夏回族自治区固原市彭阳县红河镇西南部的黑牛沟村为研究区,采用无人机倾斜摄影测量数据获取、三维建模、现场验证结合地统计学分析,开展了区域黄土滑坡识别及其特征参数提取和分析。【研究结果】基于三维实景模型确定并分析研究区沟谷沿线地貌凹陷区是否存在陡壁及其周界形态,结合色调、纹理和微地貌等标志实现了黄土滑坡识别,共圈定了23个滑坡,结合现场验证移除2个非滑坡点,最终确定了21个滑坡;滑坡密集分布在主沟和支沟沟口,多呈对滑的形式出现在沟谷两侧且具有群发性;大型及特大型滑坡占比达到57.14%,滑坡的滑动方向主要以西南(阳坡)、东南(半阳坡)为主,相对高差集中在80~120 m,滑坡体坡形多呈凹形坡,滑坡体坡度主要集中在20°~30°;滑坡体土地利用类型主要为植被,其次为裸地,也有一部分为农田,道路和河流占比极少。【结论】基于无人机倾斜摄影测量构建的三维实景模型可从多维度、多视角精确快速地识别区域黄土滑坡,并分析其相关特征参数,能够弥补当前二维平面遥感影像存在的不足;还能够为滑坡易发性、危险性、易损性及风险评估等相关研究提供数据支撑。

贴近摄影与倾斜摄影测量技术在宗教活动场所三维建模的应用

探索了贴近摄影与倾斜摄影测量技术在宗教活动场所三维建模中的应用,通过无人机平台挂载设备对场所进行采集和处理,进行多源数据融合三维建模,实现宗教活动场所的三维模型重建。本文的研究不仅为宗教活动场所的数字化保护利用和文化传承提供了新的思路和技术方法,也为其他文化遗产的数字化保护利用提供了非常有价值的参考。

腰椎融合术中恢复椎间隙自然高度对手术疗效的影响

目的 探讨腰椎融合术中恢复椎间隙自然高度对手术疗效的影响。方法 测量100名健康志愿者腰椎各椎间隙高度和椎体高度,计算各椎间隙高度与椎体高度的比值及其95%置信区间(CI),并以此为正常值参考标准,将2019年6月-2021年6月接受腰椎后路融合术治疗的133例患者根据手术节段术后椎间隙高度与椎体高度比值是否在正常值95%CI内分为自然高度组(n=78)和非自然高度组(n=55)。记录并统计2组患者术中及术后并发症发生率,采用疼痛视觉模拟量表评分(VAS)和日本骨科学会(JOA)评分评估手术前后疼痛程度及神经功能。结果 末次随访时,自然高度组发生邻椎病3例,并发症发生率为3.8%;非自然高度组发生邻椎病5例,足下垂1例,并发症发生率为10.9%;2组并发症发生率差异有统计学意义(P <0.05)。2组术后各随访时间点腰腿痛VAS评分、JOA评分较术前明显改善,末次随访时自然高度组腰腿痛VAS评分、JOA评分改善率优于非自然高度组,差异均有统计学意义(P <0.05)。结论 腰椎融合术中椎间隙的撑开高度应参照椎体自身高度,控制手术节段的椎间隙高度与椎体高度比值在正常值95%CI内可有效改善神经功能并降低并发症发生率。

倾斜摄影与激光点云融合建模在城中村精细化测绘的探索应用

城中村通常建筑密集且视野狭小,导致测量环境复杂,限制了传统工程测量尤其是建筑物精细测绘的作业精度与效率,本文以广州市城中村为例,探索了联合倾斜摄影与激光点云建模在精细化测绘的应用。无人机倾斜摄影测量通过多角度空基观测捕捉密集建筑群落立体信息;激光扫描通过连续设置地基站获取点云数据,进行去噪、配准、分割等处理。利用Iterative Closest Point算法将点云与倾斜摄影数据配准,通过激光点云弥补倾斜摄影模型近底部遮挡区域并细化其几何细节,得到高精度城中村实景三维模型。试验结果表明,融合倾斜摄影与激光点云的三维模型可满足城中村精细化测绘要求,具有一定的应用价值。

基于数字摄影测量的馆藏文物三维重建方法研究

为了降低人为操作对文物的损害风险,需开展馆藏文物三维重建方法的研究,以通过数字化技术的应用实现对文物的非接触性记录和数字化保存。目前,现有的三维重建方法存在重建图像的清晰度较低,还原度较差等缺点,因此本文提出了一种基于数字摄影测量的馆藏文物三维重建方法。首先对馆藏文物进行图像采集;然后提取文物的特征点,并通过匹配馆藏文物影像来获取对应关系;再采用不规则离散点构建三角不规则网格(TIN)来建模文物的三维形状;最后,为进一步提高重建效果,进行纹理映射,将高质量的图像纹理信息应用到三维模型上。经过测试和分析,验证了所提出的方法在馆藏文物的三维重建中具有良好的整体效果,分辨率可达到预期的2800像素×2800像素。该方法可为文物修复工作提供可靠的参考依据。