A Self-calibration Bundle Adjustment Algorithm Based on Block Matrix Cholesky Decomposition Technology

In this study,the problem of bundle adjustment was revisited,and a novel algorithm based on block matrix Cholesky decomposition was proposed to solve the thorny problem of self-calibration bundle adjustment.The innovation points are reflected in the following aspects:①The proposed algorithm is not dependent on the Schur complement,and the calculation process is simple and clear;②The complexities of time and space tend to O(n)in the context of world point number is far greater than that of images and cameras,so the calculation magnitude and memory consumption can be reduced significantly;③The proposed algorithm can carry out self-calibration bundle adjustment in single-camera,multi-camera,and variable-camera modes;④Some measures are employed to improve the optimization effects.Experimental tests showed that the proposed algorithm has the ability to achieve state-of-the-art performance in accuracy and robustness,and it has a strong adaptability as well,because the optimized results are accurate and robust even if the initial values have large deviations from the truth.This study could provide theoretical guidance and technical support for the image-based positioning and 3D reconstruction in the fields of photogrammetry,computer vision and robotics.

Comparison between Plane and Stereo Block Adjustment for ZY-3 Satellite Images

Block adjustment for satellite images cannot be solved with weak convergence geometric conditions,therefore a plane block adjustment method to improve the targeting precision of images is proposed utilizing DEM as height constraint plane block adjustment method.First,a rational function model with affine transformation is selected as the mathematical model of the satellite image plane block adjustment.Second,to update the ground coordinates of tie points(TPs),the plane coordinates of TPs are only solved in the adjustment process.Elevation values are obtained by using DEM interpolation.Finally,the plane coordinates of all TPs and orientation parameters of all satellite images are solved through plane block adjustment with a few ground control points ZY-3 nadir images for two regions are tested for plane block adjustment while ZY-3 forward-nadir-back images of the same two regions are tested for stereo block adjustment.A comparison indicates that almost the same accuracy can be obtained with plane block adjustment support using a 1∶50 000 DEM and stereo block adjustment for ZY-3 images.For ZY-3 nadir images,almost no loss of plane block adjustment accuracy occurred when global DEM with 1 km grid and SRTM with 90 m grid replaced the 1∶50 000 DEM as elevation control,.Test results demonstrate the effectiveness and feasibility of the plane block adjustment method.

Study on Injection-Production System Adjustment of Fault Block Reservoir Based on Equilibrium Displacement

This paper proposed a method of injection-production system adjustment to solve the problem that the water flooding effect was restricted because of the horizontal and vertical contradictions during the development process of fault block reservoirs. Considering the heterogeneity of reservoir, the Buckley-Leverett water flooding theory was applied to establish the relationship between the recovery and cumulative water injection. In order to achieve the goal of vertically balanced recovery of each section, the calculation method of vertical sectional injection allocation was proposed. The planar triangular seepage unit was assumed and sweep coefficients of different oil-water distribution patterns were characterized using multi-flow tube method. In order to balance and maximize the plane sweep coefficient, the calculation method of plane production system optimization was obtained. Then the injection-production system stereoscopic adjustment method based on equilibrium displacement was proposed with vertical sectional injection allocation and plane production system optimization. This method was applied to injection and production adjustment of BZ oilfield in southern Bohai. The effect of water control and oil increase was obvious. This method can greatly improve the effect of water flooding of offshore fault block reservoirs with the adjustment of injection-production system.

Multi-toning Image Adjustment

Due to the different lighting environments or other reasons, the pixel colors may be quite different in one image which causes distinct visual discontinuities. It makes the analysis and processing of such an image more difficult and sometime impossible. In this paper, a unified multi-toning image adjustment method is proposed to solve this problem. First, a novel unsupervised clustering method was proposed to partition the source and the target image into a certain number of subsets with similar color statistics. By matching the texture characteristics and luminance distribution between the blocks, it can create optimized correspondence. Then, the color information was transferred from the matched pixels in the source blocks to the target ones. Graph cut method was used to optimize the seams between different subsets in the final step. This method can automatically perform color adjustment of a multi-toning image. It is simple and efficient. Various results show the validity of this method.

油藏不同开发阶段层面建模算法及实例

由于油藏不同开发阶段特征及其研究目的不同,三维地质建模中层面建模采取的模拟方法和模型精度均有所区别。从三维地质建模角度出发,将油藏开发划分为油藏评价、新区建产和老区调整3个阶段,通过港东二区五断块层面模拟过程中各种模拟算法分析及筛选,提出了层面模拟时,油藏评价阶段建模采用Kriging算法,网格精度为100 m×100 m×5.0 m;新区建产阶段建模采用Kriging算法或Global B-spline算法,网格精度为50 m×50 m×1.5 m;老区调整阶段建模采用Local B-spline算法或Converging average算法,网格精度为10 m×10 m×0.5 m,使层面模拟结果更符合地质情况及研究需要。

陆地碳监测卫星光学立体影像定位精度分析

陆地碳监测(terrestrial carbon monitor satellite,CM-1)卫星主要应用于陆地生态资源调查监测,因此,对其光学立体影像定位精度及DSM质量分析具有重要意义。首先,利用参考影像和AW3D30 DEM数据,在CM-1卫星立体影像上匹配一定量控制点,进行区域网平差,以验证CM-1卫星影像立体定位精度;随后,将CM-1立体影像提取的DSM数据分别与AW3D30 DEM和ICESat-2激光测高数据对比分析;最后,利用平均值、标准差和均方根误差3项指标评估CM-1立体影像提取的DSM精度。结果表明,有控条件下,相对于数字正射影像,CM-1卫星立体影像在平原地区平面定位精度达到1 m,相对于AW3D30 DEM,平原地区高程定位精度达到1.57 m。前视后视立体影像提取的DSM精度高于前视正视、后视正视立体影像提取的DSM精度。

轻小型无人机载激光雷达测量系统检校方法

轻小型无人机载激光雷达测量系统具有成本低廉、作业便利等优势,其应用领域越来越广泛。但现有系统由于控制成本等原因,使其直接采集的点云数据质量不高,必须通过地面检校来消除系统误差。设计了一套适用于轻小型无人机载激光雷达测量系统的检校方案,首先设计了一种可灵活组装与使用的圆型靶标器,其次建立了以航带点云为单元的区域网平差模型,最后通过精确测量靶标器中心点的真实地面坐标和采集点云坐标,平差求解出每条航带点云的几何校正参数并以大疆禅思L1激光雷达测量系统为例对该方法进行了实验。结果表明该方案可显著提升原始点云的定位精度。此外,通过设计不同的靶标器布设方案对检校实施方案进行了探讨,总结了靶标器最佳布设原则。

单家寺油田采出液沉积物调堵运用与效果

针对不同油藏特点,选择开展边部堵水调剖和蒸汽流场调整两项工作实验,并在单家寺油田稠油区块进行了10口井采出液沉积物边部堵水与蒸汽流场调整试验,现场应用效果好,为消化石油采出过程中伴生的废弃物提供了一条绿色之路。

柳沟区块层系调整及井网优化技术应用

为提高多层系油藏叠合发育区块开发效果,以柳沟区块为研究区,考虑投入产出比、井筒寿命及水淹规律,分析叠合区层系调整时机,利用数值模拟进行井网优化选择。结果表明,当油井成本大于收益、套损井平均生产年限为12年及快速水淹时宜进行研究区层系调整;选择反七点井网调整时研究区采收率最高;通过井网调整,注采对应率明显提高(21%),水驱动用程度明显提高(42.22%),自然递减率明显下降(11.77%下降为6.58%),最终采收率明显增加(6.02%),技术可采储量明显增加(85.75×10^(4)t)。该研究可对柳沟区块及同类区块的有效开发提供理论指导。

Novel block-matching algorithms by subsampling both search candidates and pixels

A new faster block-matching algorithm （BMA） by using both search candidate and pixd sulzsamplings is proposed. Firstly a pixd-subsampling approach used in adjustable partial distortion search （APDS） is adjusted to visit about half points of all search candidates by subsampling them, using a spiral-scanning path with one skip. Two sdected candidates that have minimal and second minimal block distortion measures are obtained. Then a fine-tune step is taken around them to find the best one. Some analyses are given to approve the rationality of the approach of this paper. Experimental results show that, as compared to APDS, the proposed algorithm can enhance the block-matching speed by about 30% while maintaining its MSE performance very close to that of it. And it performs much better than many other BMAs such as TSS, NTSS, UCDBS and NPDS.

涪陵气田焦石坝区块页岩气持续稳产技术政策优化

涪陵页岩气田是我国首个实现商业化规模开发的页岩气田,主力产区焦石坝区块自2017年底开始有70%的气井进入递减阶段,稳产面临极大挑战。为保障气田持续稳产,基于焦石坝区块已实施的一次井网257口井生产资料,分析了上奥陶统五峰组—下志留统龙马溪组储量动用情况,通过开展地质建模和数值模拟一体化为核心的储量动用状况评价技术攻关,明确了焦石坝区块一次井网开发下的剩余气分布情况,建立了地质、地面、工艺及经济“四位一体”的开发调整井水平段长度优化技术,形成了页岩气开发调整技术政策优化技术,指出了区块下一步提高采收率的方向。研究结果表明:①焦石坝区块一次井网中①—⑤小层600 m井距之间的储量动用不充分,⑥—⑨小层在裂缝不发育区储量基本未动用,在裂缝发育区储量部分动用;②基于剩余储量最富和压裂改造最易两大原则,优化了开发调整井最优穿行层位,下部气层加密井水平段穿行轨迹以①小层为主,上部气层井最优水平段轨迹为⑦小层顶之下的6 m;③以压裂干扰、投产干扰核心评价方法为基础,通过开展不同井距试验,优化建立了同层系300 m井距、上下部气层投影井距150 m的开发调整井网井距优化技术。结论认为,通过焦石坝区块一期井网的生产动态分析,明确了焦石坝区块剩余气分布情况,并建立了开发调整井提高采收率技术,为保障涪陵页岩气田的持续稳产提供了技术支撑,对于我国非常规油气资源高效、经济动用具有重要的参考借鉴和示范推广意义。

基于改进YOLOv3的交通标志识别

针对交通标志在图像中占比小,存在难以准确识别的问题,提出以YOLOv3网络模型为基础的改进算法对交通标志进行识别。调整网络中的CBL层,使用较浅层次网络的输出特征图,降低漏检率;采用焦点损失函数计算置信度,降低了误报率和对数平均未命中率;将图像分块预处理,解决较小的对象特征因图像大小调整而丢失的问题,提高主干网络检测速度。该算法在中国交通标志数据集上验证结果表明,提高YOLOv3网络的平均精度和整体性能,mAP达到97.84%,速度达35.6fps。

面向高分三号全球正射影像生成的无控定位精度提升方法

高分三号(GF-3)是我国首颗C频段多极化高分辨率合成孔径雷达(synthetic aperture radar,SAR)卫星,由于GF-3卫星影像初始几何定位精度不高,难以直接满足大区域高精度制图需求。本文提出了一套面向全球正射影像生成的无控定位精度提升方法,首先通过几何再定标提升单景SAR影像的初始定位精度,其次利用SAR-SGFM匹配算法,结合自适应区域网平差方法精化影像几何模型参数,显著提升大规模SAR正射影像生成中的几何精度和处理效率。通过大规模数据生产验证,GF-3正射影像绝对几何精度优于10 m(1个像素),相对几何精度优于1个像素。结果表明,本文方法在超大规模星载SAR正射影像生产中具有有效性和可行性。

基于最优路径的无人机影像辐射区域网平差

无人机遥感能够提供高时空分辨率的影像数据,拥有广泛的应用前景。辐射校正将传感器记录的数据转化为地表反射率,是无人机数据定量化应用的前提。然而无人机数据易受光照等因素的影响,导致影像间存在不同程度的辐射差异,为多张无人机影像的辐射校正带来困难。基于影像间重叠区域的信息,辐射区域网平差能够获得全局最优的辐射校正参数,降低影像间的辐射差异,因此在实现影像的辐射校正方面具有巨大潜力。但大量待求解未知参数降低了辐射校正模型的求解效率,特别是在数据量急剧增加时,该问题更为突出。基于影像重叠区辐射信息建立的最优路径很好地考虑了影像间的辐射转化关系,可有效控制误差累计,为减少辐射区域网平差中未知参数的数量提供了一种思路。因此,本文将最优路径与辐射区域网平差相结合,以降低待求解参数的数量,在保证辐射校正精度的同时提高辐射校正模型求解效率,进而提升辐射区域网平差在大数据集上的应用潜力。

治理重心下移中的反向调适:城市街区治理的实现及其逻辑——以上海市F街区为例

在城市治理重心下移的背景下,在街道与居民区之间设置街区这一反向调适何以出现?现有城市基层治理文献对其关注还不够。本文采用个案研究法,基于上海市X区F街区的田野资料,展示了城市街区治理的实现过程与逻辑。研究发现,辖区党委和政府对上级政策的识别、回应与对民意诉求的回应相互交织,推动了街区治理方案进入政策议程;而街区治理方案落地后,包括党建联盟机制、协商议事机制、资源共享机制、集体行动机制在内的治理规模做大机制促进了街区治理的实现。这一过程贯穿着两个逻辑:一是地方党委和政府在识别和回应上级政策信号的同时利用政策之窗将民意诉求整合进政策方案;二是地方党委和政府适度扩大治理规模,设计出街区这一层级,低成本地解决了一系列跨居民区的棘手问题,实现有效治理。本文的政策启示在于,城市治理重心下移背景下地方党委和政府需要根据事务设置合适的治理层级以形成恰当的治理规模。

高分七号与资源三号卫星联合服务机场净空监测

针对机场净空监测DSM生产需求,本文基于高精度控制资料对高分七号(GF-7)卫星影像进行立体匹配,得到DSM数据,但高层、超高层建筑匹配效果不佳,人工立体编辑工作量较大,因此对GF-7与资源三号(ZY-3)卫星影像进行联合区域网平差,采取多视准核线影像匹配、全局优化遮挡检测与视差空洞修补等技术,立体匹配得到高精度DSM数据,有效提取出高层、超高层建筑,为机场净空监测提供了基础空间数据。

基于三自由度液压小车的总段低应力调姿技术

针对液压小车在执行部分指令时球头可能会发生滑移,且现场制定的调姿指令存在局部受力不合理的问题,设计一套具备三自由度油缸协同运动能力的液压系统。对常见调姿工况进行了有限元分析,在此基础上提出保证总段低应力状态的调姿指令计算准则及具体计算方法,最终通过实验验证了该液压系统和相应调姿控制算法的可行性。

田东油田开发调整潜力评价方法研究

针对田东油田油藏构造复杂、油水井地质条件及注采状况差异大、开发中后期措施潜力评价难等问题,文章依据油田经营及经济条件,采用技术与经济相结合的方法,研究了开发调整界限确定方法,并结合油田地质和开发动态实际,评价了开发调整潜力,为油田综合调整方案编制及开发调整提供依据。

高分七号卫星立体影像无地面控制区域网平差与精度验证

开展基于高分七号卫星(GF-7)立体影像的无控区域网平差精度分析验证,对GF-7能否实现1∶1万比例尺立体测图具有重要意义。文章选取了覆盖中国河北太行山地区的GF-7立体影像和激光点作为实验数据,开展无地面实测控制点条件下的区域网平差实验。结果表明,在无激光点辅助的情况下,实验影像在各类地形及整区的平面精度均满足1∶1万比例尺测图要求,但高程精度超限。采用激光点作为控制与立体影像开展联合区域网平差后,实验影像平面和高程精度均满足1∶1万比例尺测图要求。因此,在无地面实测控制条件下,利用GF-7激光点作为高程控制,GF-7影像几何精度可满足1∶1万比例尺立体测图精度要求,这对未来开展全球范围1∶1万比例尺地理信息资源建设具有重要意义。

幼儿教师待遇政策执行阻滞与路径调适分析——基于史密斯政策执行过程模型

利用史密斯政策执行过程模型从政策本身、执行主体、目标群体和执行环境四个方面分析幼儿教师待遇政策执行阻滞的原因,发现政策内容模糊不清、执行主体执行不力、目标群体没有发言权、缺乏经济支撑和强力监督是使该政策执行受阻的主要因素。对此,需要通过“抓住立法契机,推动制度设计;增加投入,关注教师;严格监管,加强问责”等路径加以调适。