Endmember graphics

Thek points inp-space corresponding to a specified set ofk (k<p) linearly independent endmember estimates associated with ap-variate (n×p) compositional datasetX, define the vertices of a (k–1) dimensional simplexH. Then estimated mixtures which together account for the systematic variation in the datasetX, are each convex combinations of thek fixed endmember estimates. Accordingly, then-points inp-space which represent these mixtures must be interior points of the simplexH. The purpose of this paper is to describe a simple graphical procedure for examining the positions of the estimated mixtures relative tok=3 or 4 putative endmembers, and for assessing their compliance or otherwise with the convexity constraints. Since the mixture coefficients must be estimated first in order to obtain the mixture estimates, the paper begins with a review of the least-squares partitioning procedure.     

Statistical graphics in geochemical journals

A quantitative investigation of types of statistical graphics and maps being used for presentation of geochemical data has been made for the 1984 volumes ofGeochemica et Cosmochimica Acta, Chemical Geology, Contributions to Mineralogy and Petrology, Geochemistry International, Journal of Geochemical Exploration, Journal of Petrology, and the 1983 volume ofOrganic Geochemistry. Although a number of significant differences exist between relative proportions of text, tables, statistical graphs and maps, and other illustrations in the various journals, overall figures are comparable broadly to those found by Cleveland (1984) in a recent survey of usage in 57 journals in natural, mathematical, and social sciences. Between 18% and 35% of 1463 graphs and maps in these journals contain at least one item of error or poor presentation, indicating the need for substantial improvement in both standards of preparation and refereeing of diagrams, and we suggest guidelines for both authors and referees.Presented at the Computer Graphics in Geology meeting of the Geological Information Group of the Geological Society of London, held at the University of Bristol, England, 23 May 1985.     

Endmember orthonormal mapping in hyperspectral mixture analysis to address endmember variability

Spectral unmixing estimates the abundance of each endmember at every pixel of a hyperspectral image. Each material in traditional unmixing algorithms is represented through a constant spectral signature. However, endmember variability always exists due to environmental, atmospheric, and temporal conditions, which leads to poor accuracy of the estimated abundances. This paper proposes a new unmixing algorithm based on a new linear transformation called endmember orthonormal mapping (EOM) to overcome the aforementioned problem. The EOM transformation maps original spectral space to a new EOM space to reduce endmember variability. In the original spectral space, each material is represented by a set of spectra (endmember set) which is extracted using the automated endmember bundles (AEB) method. The EOM transforms each endmember set to a vector in the EOM space so that these vectors are orthonormal. On account of orthonormalized endmembers, the condition number of the mixing matrix in the EOM space reduces. Furthermore, we consider the noise term as an additional virtual endmember set mapped to a vector that is orthogonal to other endmembers. As a result, a promising unmixing accuracy is obtained through applying the least squares abundance estimation in the subspace orthogonal to noise. Experimental results of both synthetic and real hyperspectral images demonstrate that the proposed algorithms provide much enhanced performance compared with the state-of-the-art algorithms.     

地质戴帽中的图形裁剪算法

地质戴帽根据地表地质构造特征绘制与地震剖面连为一体的岩性剖面,可极大提高解释精度。但目前该项技术一直沿用传统的手工绘制,效率低、图形质量不高。这里提出将多边形线裁剪算法应用在地质戴帽的绘图中：首先对地质戴帽的采集数据分类,构成任意多边形和线段并实现线裁剪,在此基础上,将裁剪之后的线段和原多边形成块,构成新的封闭块区,然后针对不同地质属性块填充相应岩性符号,准确高效的实现了地质戴帽绘图。     

基于MapGIS—Surfer联合的地球化学制图

首先对比Surfer和MapGIS软件的优缺点,主要在于：Surfer具有强大的数据处理功能,图形处理较差;MapGIS具有完美图形处理功能而数据处理功能较差。其次指出部份学者在应用这二款软件中的不足之处,并提出以MapInfo文件格式为数据交换基础的,基于MapGIS—Surfer联合图方法。最后给出了基于MapGIS和Surfer联合制作地球化学图及规范化操作,旨在提供一种将这二款软件优势充分发挥出来,且具有快速、高效、高质量、低成本的地球化学图件制作之途径。     

Displaying geological 3-D surfaces using computer graphics

Now that increasing quantities of geological information are being handled by computer, computer graphic techniques are being used more and more to display the information in graphical form. In this article I show that computer graphic techniques for displaying surfaces have applications in many branches of geology.     

Endmember analysis of heavy-metal pollution in surficial sediments from the Gulf of Gdansk and the southern Baltic Sea off Poland

Thirty one bulk (<2 mm) samples of surficial sediments from the Gulf of Gdansk and the Southern Baltic Sea off Poland were analyzed for 20 elements and the resulting compositional dataset was subjected to endmember analysis. The compositions of 4 endmember estimates were constructed and the abundances of these endmembers were calculated for each sample. Copper, Zn and Ag appear on one endmember and Cd and Pb on another. This suggests that Cu, Zn and Ag are introduced into the Gulf of Gdansk principally from the Vistula River whereas Cd and Pb are introduced as a result of atmospheric and riverine transport of these elements. The dual source of Cd and Pb into the Gulf of Gdansk may explain the complex interelement relationships displayoed by these elements in the sediments from this region.     

中国地学断面CorelDRAW图形数据库资源整合综合研究

整合了历时数年(2001—2006)数字化研究取得的中国全部11条地学断面图各种专业图件的CorelDRAW图形数据资源及其说明书。参照国际全球地学断面(GGT)数字化编图指南,独立研制了全球地学断面图的GGTCorelDRAW制图色盘和模板,为应用和普及制作地学断面图提供了软件工具。建立了网页类型的中国地学断面元数据库,编撰了地学断面电子字典帮助文件。上述综合研究工作为中国地学断面图资源共享提供了底层数据和技术支撑。     

Dynamic programming with colour graphics smoothing for open-pit design on a personal computer

Summary Dynamic programming is a technique which has been used to design the optimum final surface mining pit limit. In using dynamic programming there is a trade-off: if the geometric constraints are specified too strictly, the pit limit will not be the optimum, but if they are specified more loosely, then the computed pit contours must be smoothed. The smoothing process has usually been manual and is time consuming. In this paper a colour graphics computer routine is presented. This not only facilitates the smoothing but also has the following benefits: open-pit limits can be designed interactively on a personal computer; pit designs that are closer to the economic optimum can be obtained; and the engineer can bring his or her own experience and intuition to bear on the final open-pit design.     

有限元软件与通用图形软件间无缝连接的研究

采用面向对象技术,结合已开发的自适应有限元软件AFEAS,探索并实现了它和AutoCAD软件图形的无缝连接,并给出了一个简单的滑坡示例,验证了该方法的可行性和优点。     

地球物理数据处理技术中的图形与感兴趣区编辑技术的研究与实现

图形编辑与感兴趣区编辑在地球物理数据处理中应用越来越广泛。这里借鉴CAD中图形编辑的功能,研究与实现了地球物理数据处理中人机交互图形编辑的基本功能。在图形编辑的基础上,进行了图形所对应图像的属性编辑,进而实现了在遥感数据处理中感兴趣区编辑的基本功能。     

基于高分数据的广东省矿山复绿现状遥感调查

提出了矿山复绿的技术方法和技术路线。通过开展广东省矿山复绿遥感调查,获取较为真实的广东省矿山复绿最新状况。指出广东省矿山复绿存在的主要问题,并提出有益的建议和对策,希望遥感能够作为技术支撑更好地为矿政管理服务。     

Reduction of computing time for least-squares migration based on the Helmholtz equation by graphics processing units

In geophysical applications, the interest in least-squares migration (LSM) as an imaging algorithm is increasing due to the demand for more accurate solutions and the development of high-performance computing. The computational engine of LSM in this work is the numerical solution of the 3D Helmholtz equation in the frequency domain. The Helmholtz solver is Bi-CGSTAB preconditioned with the shifted Laplace matrix-dependent multigrid method. In this paper, an efficient LSM algorithm is presented using several enhancements. First of all, a frequency decimation approach is introduced that makes use of redundant information present in the data. It leads to a speedup of LSM, whereas the impact on accuracy is kept minimal. Secondly, a new matrix storage format Very Compressed Row Storage (VCRS) is presented. It not only reduces the size of the stored matrix by a certain factor but also increases the efficiency of the matrix-vector computations. The effects of lossless and lossy compression with a proper choice of the compression parameters are positive. Thirdly, we accelerate the LSM engine by graphics cards (GPUs). A GPU is used as an accelerator, where the data is partially transferred to a GPU to execute a set of operations or as a replacement, where the complete data is stored in the GPU memory. We demonstrate that using the GPU as a replacement leads to higher speedups and allows us to solve larger problem sizes. Summarizing the effects of each improvement, the resulting speedup can be at least an order of magnitude compared to the original LSM method.     

A distributed parallel multiple-relaxation-time lattice Boltzmann method on general-purpose graphics processing units for the rapid and scalable computation of absolute permeability from high-resolution 3D micro-CT images

Digital rock physics (DRP) is a rapidly evolving technology targeting fast turnaround times for repeatable core analysis and multi-physics simulation of rock properties. We develop and validate a rapid and scalable distributed-parallel single-phase pore-scale flow simulator for permeability estimation on real 3D pore-scale micro-CT images using a novel variant of the lattice Boltzmann method (LBM). The LBM code implementation is designed to take maximum advantage of distributed computing on multiple general-purpose graphics processing units (GPGPUs). We describe and extensively test the distributed parallel implementation of an innovative LBM algorithm for simulating flow in pore-scale media based on the multiple-relaxation-time (MRT) model that utilizes a precise treatment of body force. While the individual components of the resulting simulator can be separately found in various references, our novel contributions are (1) the integration of all of the mathematical and high-performance computing components together with a highly optimized code implementation and (2) the delivery of quantitative results with the simulator in terms of robustness, accuracy, and computational efficiency for a variety of flow geometries including various types of real rock images. We report on extensive validations of the simulator in terms of accuracy and provide near-ideal distributed parallel scalability results on large pore-scale image volumes that were largely computationally inaccessible prior to our implementation. We validate the accuracy of the MRT-LBM simulator on model geometries with analytical solutions. Permeability estimation results are then provided on large 3D binary microstructures including a sphere pack and rocks from various sandstone and carbonate formations. We quantify the scalability behavior of the distributed parallel implementation of MRT-LBM as a function of model type/size and the number of utilized GPGPUs for a panoply of permeability estimation problems.