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.

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。

基于Photogrammetry的地表变形监测技术研究

主要讨论了采用Photogrammetry技术监测地下施工过程中地表变形的主要方法和应用情况。地表变形过大往往会导致地表既有建筑物的破碎,所以量化监测其变形程度在地下施工中尤为重要。Photogrammetry技术是一种非接触式的变形监测技术,主要通过影像手段获取目标点的三维变形大小。该方法需要从空间多角度对目标点进行摄影测量,获取连续的三维影像信息,通过Photogrammetry软件进行现场目标点重现,进而获取三维可视目标点坐标值。本文通过现场的监测,获取了地表变形的数据,提出了监测的方法。

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.

基于Photogrammetry的矿区地表沉降检测技术研究与应用

对Photogrammetry技术的主要原理进行了解析,并利用该技术从空间多角度对预先设置的20个目标点进行图像采集,获取连续的三维影像信息,通过PM软件进行采矿区目标点重现,获得了各个检测点的三维坐标大小,并对两种焦距下的图像处理结果进行了对比分析,对实际工程应用具有借鉴意义。

基于Photogrammetry的非开挖施工地表变形检测技术研究

非开挖施工过程中由于往往受到埋深的限制，导致上部土体有效应力降低，进而产生地表变形，变形过大还会引起地表既有建筑受到破坏，所以量化检测其变形程度在地下施工中尤为重要。本文主要讨论了采用Photogrammetry技术检测非开挖施工过程中地表变形的主要方法和应用情况。Photogrammetry技术是一种非接触式的变形检测技术，主要通过影像手段获取目标点的三维变形大小。该方法需要从空间多角度对目标点进行摄影测量，获取连续的三维影像信息，通过Photogrammetry软件进行现场目标点重现，进而获取三维可视目标点坐标值。本文通过现场的检测，获取了地表变形的数据，提出了检测的方法，并对数据处理过程中检测精度提出了探讨。

高分辨率倾斜摄影测量技术在农村房地一体测量中的应用研究

传统的农村房地一体测量方法效率低、周期长、工作量大,很难满足当前时间紧、任务重的工作要求。无人机倾斜摄影测量技术被越来越多的应用到测绘领域,文章采用高分辨率无人机倾斜摄影测量技术开展农村房地一体测量工作,阐述了采用无人机倾斜摄影测量技术进行三维建模的流程,并对成果的平面位置和边长精度进行了检测,结果表明无人机倾斜摄影测量技术能够很好的满足农村房地一体测量工作的要求,并且在后续村庄规划、三维不动产等方面具有很大的应用空间。

无人机倾斜摄影测量在不动产测绘中的应用

为了提升不动产测绘的效率和精度,本文详细介绍了无人机倾斜摄影测量的应用流程。首先,通过合理的航线规划确保数据采集的全面性;其次,布置像控点以提高影像的几何精度;随后,进行多视影像预处理和空中三角测量,以优化影像质量;接着,采用多视影像密集匹配技术获取高精度点云数据;进而,构建点云构网与三维测绘模型;最后,对三维测绘精度进行评价。研究结果表明,无人机倾斜摄影测量在不动产测绘中能够显著提高测绘效率和精度,为不动产管理提供了有力支持。

无人机倾斜摄影测量智能技术在铁路工程项目中的应用分析

高精度、低成本等特点的无人机倾斜摄影测量智能技术在铁路工程项目中表现出良好应用价值。文章研究了无人机倾斜摄影测量智能技术在铁路工程项目中应用方法。在掌握技术概念的基础上,分析了无人机倾斜摄影测量智能技术的实践意义,同时,强调了航线规划、执行飞行任务、数据处理、构建三维模型、模型修饰与优化等的应用路径,有助于转变传统工程测量模式,充分发挥新兴无人机倾斜摄影测量智能技术的应用价值,提高铁路工程建设成效,推动行业健康发展。

Effects of far-off and close-up transition cow feeding on uterine health,postpartum anestrous interval,and reproductive outcomes in pasture-based dairy cows

Background:In seasonal,pasture-based,dairy production systems,cows must recover from calving and become pregnant within two to 3 months.To achieve this,the uterus must involute and ovulation must occur and continue at regular intervals.As these processes are affected by the cows’nutritional or metabolic status post-calving,the objective of this study was to evaluate the effect of cow feeding strategies on uterine health,the length of postpartum anestrous interval,and reproductive outcomes.The treatments consisted of two feeding strategies during late-lactation and early dry period(far-off period;starting 4-month pre-calving)and three close-up dry period feeding regimes(1-month pre-calving)in a 2×3 factorial arrangement.We randomly assigned 150 cows to one of two far-off treatments.During late lactation,the herds(n=75 cows per herd)were either control-fed(Controlfed)or over-fed(Overfed)to achieve a low or high body condition score(4-month pre-calving;BCS;~4.25 and^4.75;10-point scale)at cessation of lactation.Within each of these treatments,three feeding levels were applied during the close-up period(1-month pre-calving):~65%(Feed65),~90%(Feed90),or^120%(Feed120)of metabolizable energy(ME)intakes relative to pre-calving requirements.Results:Uterine health improved(i.e.polymorphonucleated(PMN)cells declined)with increased feeding during the close-up period for cows in the Overfed group.The reverse was evident for the Controlfed group with the greatest PMN at the highest intakes during the close-up period.The postpartum anoestrous interval(PPAI)was shorter in cows from the Overfed group when moderately fed(Feed90)during the close-up period;in comparison,the PPAI was shorter in the Controlfed group,when those cows were overfed in the close-up period(Feed120).The cows in the Overfed treatment had greater conception and pregnancy rates if cows had moderate dry matter intakes(Feed90)during the close-up period;these reproductive variables were less under excessive feed intakes(Feed120);yet,close-up dry matter intake had little effect on conception and pregnancy rates for the Controlfed group.Conclusions:The far-off feeding strategies increased early reproductive outcomes at 3 weeks of mating.Additionally,the interaction between far-off and close-up feeding strategies resulted in high six-week pregnancy rate with a slight restriction during the close-up period but only in the far-off Overfed group.Thus,our hypothesis is supported under these conditions.

Photogrammetry as a tool for the postural evaluation of the spine:A systematic review

AIM:To evaluate the use of photogrammetry and identify the mathematical procedures applied when evaluating spinal posture.METHODS:A systematic search using keywords was conducted in the Pub Med,EMBASE,Scopus,Science and Medicine®databases.The following inclusion criteria adopted were:(1)the use of photogrammetry as a method to evaluate spinal posture;(2)evaluations of spinal curvature in the sagittal and/or frontal plane;(3)studies published within the last three decades;and(4)written entirely in English.The exclusion criteria were:(1)studies which objective involved the verification of some aspect of validation of instruments;(2)studies published as abstracts and those published in scientific events;and(3)studies using evaluation of the anteriorization of the head to determine the angular positioning of the cervical spine.The articles in this review were included and evaluated for their methodological quality,based on the Downs and Black scale,by two independent reviewers.RESULTS:Initially,1758 articles were found,76 of which were included upon reading the full texts and 29 were included in accordance with the predetermined criteria.In addition,after analyzing the references in those articles,a further six articles were selected,so that 35 articles were included in this review.This systematic review revealed that the photogrammetry has been using in observational studies.Furthermore,it was also found that,although the data collection methodologies are similar across the studies,in relation to aspects of data analysis,the methodologies are very different,especially regarding the mathematical routines employed to support different postural evaluation software.CONCLUSION:With photogrammetry,the aim of the assessment,whether it is for clinical,research or collective health purposes,must be considered when choosing which protocol to use to evaluate spinal posture.

Rapid and robust slope failure appraisal using aerial photogrammetry and 3D slope stability models

Slope failures are an inevitable aspect of economic pit slope designs in the mining industry.Large open pit guidelines and industry standards accept up to 30%of benches in open pits to collapse provided that they are controlled and that no personnel are at risk.Rigorous ground control measures including real time monitoring systems at TARP(trigger-action-response-plan)protocols are widely utilized to prevent personnel from being exposed to slope failure risks.Technology and computing capability are rapidly evolving.Aerial photogrammetry techniques using UAV(unmanned aerial vehicle)enable geotechnical engineers and engineering geologists to work faster and more safely by removing themselves from potential line-of-fire near unstable slopes.Slope stability modelling software using limit equilibrium(LE)and finite element(FE)methods in three dimensions(3D)is also becoming more accessible,user-friendly and faster to operate.These key components enable geotechnical engineers to undertake site investigations,develop geotechnical models and assess slope stability faster and in more detail with less exposure to fall of ground hazards in the field.This paper describes the rapid and robust process utilized at BHP Limited for appraising a slope failure at an iron ore mine site in the Pilbara region of Western Australia using a combination of UAV photogrammetry and 3D slope stability models in less than a shift(i.e.less than 12 h).

Application of Digital Photogrammetry to Measure Distribution of Tree Postions

The application of digital photogrammetry to measure distribution of tree positions with stereo image couple is introduced in detail, and the procedure of stereo vision applied in forestry environment is explored. Nonlinear error in measure model is adopted in the camera calibration; the interactive correlation matching is used under constraint of epipolar line and edge of tree detected by Canny operator. Results prove that application of digital photogrammetry technology to measure distribution of tree positions can meet demand of precision in experimental conditions.

A Strategy for Loading Oblique Photogrammetry Models and Multilayer Basemap Data

With the development of drone technology and oblique photogrammetry technology, the acquisition of oblique photogrammetry models and basemap becomes more and more convenient and quickly. The increase in the number of basemap leads to excessively redundant basemap tiles requests in 3D GIS when loading oblique photogrammetry models, which slows down the system. Aiming at improving the speed of running system, this paper proposes a dynamic strategy for loading basemap tiles. Different from existing 3D GIS which loading oblique photogrammetry models and basemap tiles inde-pendently, this strategy dynamically loads basemap tiles depending on different height of view and the range of loaded oblique photogrammetry models. We achieve dynamic loading of basemap tiles by predetermining whether the basemap tiles will be covered by the oblique photogrammetry models. The experimental results show that this strategy can greatly reduce the num-ber of redundant requests from the client to the server while ensuring the user’s visual requirements for the oblique photogrammetric model.

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.

An Elevated Perspective: Dyke-Related Fracture Networks Analysed with Uav Photogrammetry

An abundance of data from seismic and geodetic monitoring has provided new insight into dyke propagation and emplacement mechanisms.These studies show that faulting and fracturing is part of the magma

CONTROL WORK IN CLOSE RANGE PHOTOGRAMMETRY

The purpose, classification, required accuracy and surveying methods of control work for close range photogrammetry have been briefly stated. The different methods for definition of space, object coordinate system are also reviewed. It is suggested that the habitu-ally-practised rotation angle system for aerophotogrammetry in China should be used for the future teaching and resaarching work in the close range photogrammetry, and that the rotation angle system for terrestrial deformation photogrammetry should be left out in order to avoid the confuse and reduce the amount of expanse for making softwares. It has been emphasized that there are three improtant aspects in the close range control work with high accurary using the conventional method of engineering surveying: the use of standard scale for measurement of distance between two general stations, the accurate determination of start direction line between two general stations and the handling method of influence of 2C change. A method for setting up industrial surveying control net with extra-high accuracy ±(0.05–0.20) mm is presented by the author. This kind of industrial control net is necessary for batch process of large industrial components with purposes of measurement, inspect and lofting. There are some special methods of control work in the close range photogrammetry, including two methods presented by the author.