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.

THE 3-D TURBULENT PTV BY USING TWO-MEDIA PHOTOGRAMMETRY

In this paper a more extensive application of 3-D PTV on visualization and reconstruction of turbulent flows has been developed: (1) the nonlinear Perspective transformation equations on two-media photogrammetry is used to determine the camera parameters and the Position of tracks in water, (2) an optimization algorithm made the resolution of the calibration much higher, (3) the adhesion and intersection between track images have been recognized and separated by using an automated digital image processing program, so the velocity vectors have been increased in a measuring volume, (4) automatically identify the corresponding track image between stereo Pair images that instantaneously taken and calculate the positions of tracks on 3-D space, (5) a succession of velocity profiles in a turbulent flow are measured and reconstructed.

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。

基于无人机倾斜摄影测量技术与SVR算法的开采沉陷监测与预计

为实现矿区开采沉陷高精度监测与预计,将无人机倾斜摄影测量技术与支持向量回归算法(Support Vector Regression Algorithm,SVR)相结合,对赤峰市六家煤矿采区沉降量进行了监测与预计,并将预计结果与GPS实测结果进行了对比。结果表明:GPS实测矿区10 d测量沉降量为0.2~15.8 mm,东西南北区平均沉降量分别为51.2、31.5、46.6、130.8 mm,北侧沉降量分别为东、西、南侧的2.55、4.15、2.81倍,矿区北侧为沉降严重区,需要进行重点监测并制定合理有效的防治措施。基于无人机倾斜摄影测量技术与SVR算法预测的矿区东西南北区累计平均沉降量分别为49.4、31.5、45.8、134.6 mm,所有测点2种测量方式所得相对误差均在5%以内,反映出所提方法预计精度较高,为实现矿区开采沉陷高精度监测与预计提供了参考。

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。

大模型赋能智能摄影测量:现状、挑战与前景

大模型从深度学习和迁移学习技术发展而来,依靠大量的训练数据和庞大的参数容量产生规模效应,从而激发了模型的涌现能力,在众多下游任务中展现了强大的泛化性和适应性。以ChatGPT、SAM为代表的大模型标志着通用人工智能时代的到来,为地球空间信息处理的自动化与智能化提供了新的理论与技术。为了进一步探索大模型赋能泛摄影测量领域的方法与途径,本文回顾了摄影测量领域的基本问题和任务内涵,总结了深度学习方法在摄影测量智能处理中的研究成果,分析了面向特定任务的监督预训练方法的优势与局限;阐述了通用人工智能大模型的特点及研究进展,关注大模型在基础视觉任务中的场景泛化性以及三维表征方面的潜力;从训练数据、模型微调策略和异构多模态数据融合处理3个方面,探讨了大模型技术在摄影测量领域当前面临的挑战与发展趋势。

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。

基于摄影测量的三轴土体剪切带演化规律

为实现土样局部变形的定向研究,同时优化土样的变形测量精度,将数字图像测量与三轴试验结合,在不对仪器做大型改造的条件下,运用摄影测量技术改良试验.以桂林地区红黏土为研究对象,试验全程对土样全表面进行受力变形监测,并还原土样的三维重构模型,以此研究其应力应变关系、局部应变特性、剪切带演化规律.研究结果表明:(1)土样表面的剪切带内外区域具有截然不同的变形特征,带外区域变形较为均匀且变形量趋于稳定,而带内区域变形不均匀且变形量不断加剧;(2)根据土样表面不同区域间的局部应变差异,确定了剪切带开始形成、停止扩张及完全贯穿的临界状态,提出了一种判别剪切带发展阶段的方法;(3)根据判别方法,将剪切带的演化过程拆分为压缩变形、表面扩张、延伸贯穿、相对滑移四个阶段,并分析了各个阶段不同的变形规律与破坏机理.经摄影测量技术改良的三轴试验,能够得到更准确的土体局部本构关系和变形特性,为探索土的应变局部化现象提供了一种精确且经济的研究方案.

基于无人机摄影测量的矿区地形三维重建及精度分析

矿区地形三维重建对于矿区地形分析及安全生产具有重要意义。针对传统重建方式存在效率低、数据更新速度慢、成本高等问题,提出了一种基于无人机摄影测量技术的矿区地形三维重建方法。该方法使用无人机进行低空拍摄,利用SIFT特征点匹配算法得到一系列匹配点,利用特征提取、空三测量、多视影像密集匹配技术,生成不规则三角网格和纹理映射,实现对矿区地形三维模型的自动重建。试验结果表明:在足够数量和合理选取地面控制点的情况下,所提方法可以获得较高精度的矿区地形三维重建结果;三维模型重建可以全面呈现矿区地形整体形态和局部细节特征,同时具有高效和低成本等优点。所提方法可为矿区环境保护及相关分析提供更准确、高效、可靠的地形信息数据源和技术支持。

双相机工业摄影测量系统测量场误差分析与现场评定方法

针对双相机工业摄影测量系统不同应用场景下实测精度与标称精度不匹配的问题,对系统网形结构进行了深入研究。通过研究发现:当物方测量点交会角大于45°,测量点与基线水平夹角介于28°~68°,竖直视角不超过23°,且测量点位于双相机工业摄影测量系统纵深方向[0.4B,1.3B]范围内时,测量点的精度较高,超过该范围,测量点的误差将变大。本文基于以上结论提出一种采用双相机工业摄影测量系统对测量场内规定位置标准尺长度测量,通过比较标准尺测量值与标称值差异,快速评定系统测量场精度的方法。试验表明,该方法能够快速准确地评定双相机工业摄影测量系统测量场精度,对于保证系统现场作业质量,提高现场作业效率具有重要指导作用。

岩土工程表面变形监测应用技术现状分析与发展思考

本文从表面变形监测技术现状出发,阐述其技术发展历程,针对建(构)筑物、边(滑)坡、地基基础、地下工程等不同工程类型的特点,结合国家现行技术标准要求,分析当前表面变形监测方法的适用性、存在问题及可能的解决办法。分析认为:自动化监测代表当前表面变形监测发展的主流;面监测为下一阶段表面变形监测发展的重要方向;基于近景摄影测量的表面变形监测技术具有较好的发展前景。

无人机倾斜摄影在土地调查中的应用

【目的】在我国土地调查发展过程中,常因技术手段存在缺陷,导致调查工作受到一定的影响。利用无人机倾斜摄影技术来建立实景三维模型,通过三维模型来完成相关调查工作,使土地调查工作更加高效、便捷。【方法】为探讨无人机倾斜摄影技术在土地调查工作中的应用优势,使用无人机搭载单目相机来采集影像,利用ContextCapture Center软件进行三维建模,并与实际调查结果进行对比,分析三维模型的优缺点。【结果】结果证明了该方法的可行性,建立的三维建模的土地边界清晰、建筑分明,可应用到土地调查工作中。【结论】无人机倾斜摄影技术可提高土地调查工作的完成效率,同时为我国未来的国土调查等工作提供支持。