Coordinates Of Control Points Research Articles

Analysis of deriving control points from LiDAR intensity image for orthophoto production

In aerial photogrammetry need control points and has a reference to the land coordinates where the measurement location is carried out. This control point would be used in aerial photo georeferenced. But in practice it often finds severe field conditions that can affect the process of measuring control points, such a forest, mountains area and even conflict areas, which could make the process of measurement at that location impossible. LiDAR Intensity Image is one product of processing LiDAR data that can be used to produce coordinates of ground control points. So that it can reduce or eliminate the use of coordinates from GCP point measurements in the field of georeferenced in aerial photographs. This research is calculating the accuracy orthophoto produced of control points from LiDAR Intensity Image. The data used are LiDAR data and aerial photography using the Bundle Block Adjustment method. The result is orthophoto which tested for accuracy based on PERKA BIG No. 15 of 2014. The results from the CE90 and LE90 tests for orthophoto that use control points from the Premark Intensity Image are 0.433 m and 0.479 m which means fulfilling the scale 1:2500 class 1 for horizontal and vertical accuracy. For the CE90 and LE90 tests that use control points from a combination of intensity image and GCP points from GPS measurements, produce better accuracy of 0.314 m and 0.301 m so that fulfilling the scale 1:2500 class 1 for horizontal and vertical accuracy.

Simultaneous Shape and Stacking Sequence Optimization of Laminated Composite Free-Form Shells Using Multi-Island Genetic Algorithm

A simultaneous shape and stacking sequence optimization algorithm is presented for laminated composite free-form shells, by which the coupled effect of shape and stacking sequence can be considered. The optimization objective is determined as maximizing fundamental natural frequency to obtain largest stiffness of shells. Nonuniform rational B-spline (NURBS) is employed to represent free-form geometrical shapes. The coordinates of NURBS control points and fiber orientations are set up as continuous and discrete optimization variables, respectively, and optimized simultaneously. To improve the efficiency of the mixed continuous-discrete optimization, multi-island genetic algorithm (MIGA) is employed to search for the global result. Through several numerical examples, the performance of the proposed approach is demonstrated in comparison with the two-phase optimization method; the effect of boundary conditions and the setup of control points on optimal results are investigated, respectively.

INTERPOLATION AND APPROXIMATION BY RATIONAL CURVES OF BEZIER AND NURBS-CURVES

Relevance. Rational Bezier curves and NURBS curves are widely used in modeling curvilinear objects due to the great flexibility and efficiency of the method. Therefore, it is relevant to develop an interpolation method and approximation by these curves of a discrete series of points both in the plane and in three-dimensional space. Method. The work is devoted to the development of a new approach to interpolation and approximations curve fitting, represented by a set of discrete points. The analytical description of the desired curve is implemented using a rational Bezier curve and a NURBS-curve. To solve this problem, two approaches are proposed. The first approach is that the weights of the points are set in advance and then the coordinates of the points of the interpolating or approximating rational Bezier curve as well as the NURBS-curve are calculated. The second approach is that the coordinates of the points are set in advance and then the weights of the control points of the Bezier curve as well as the NURBS-curve are calculated. At the beginning of the process, are set not only coordinates, but also parameters are set to a discrete row of points, that is, each point has the following definition: T (x, y, u) on the plane or T (x, y, z, u) in the three-dimensional space, where u - parameter. To solve the interpolation problem, a system of linear equations is created in which each equation reflects the equality between the analytical formula for a curve and a given point. Moreover, the number of interpolated points cannot be more than the order of the interpolating curve. Thus, we have a system of N linear equations, where N is the number of points equal to the number of points of the curve. Unknown are N control points of the desired curve. Moreover, in the first approach, the unknowns are coordinates of control points, and in the second weights of points.To solve the approximation problem, the Least Squares method is used. In the beginning, a sum of squared functional of the terms of the differences between the analytic formula of the curve and the coordinate of the given point is created. The optimization problem of minimizing this functional is solved. For this, a system of linear equations is created., each equation of which is a derivative of the functional with respect to a given parameter and equated to zero. In the first approach, the desired parameters are the coordinates of points, and in the second weights of points. Results.Two methods of interpolation and approximation of a point series by rational Bezier curves and NURBS-curves were developed. Conclusions. The test cases carried out using computer programs and visualization of results confirm the validity of the proposed methods.

ANALYSIS OF COMMON QUALITY PROBLEMS IN COORDINATE TRANSFORMATION BETWEEN REFERENCE COORDINATE SYSTEM AND GEOCENTRIC COORDINATE SYSTEM

Abstract. In the working of the existing reference coordinate system transformed into the coordinate system of the geocentric coordinate system, many experts and scholars have in-depth research on the transformation methods such as geodetic control point results (including GNSS base station coordinates, GNSS control point coordinates, triangle point coordinates), basic geographic information data results (including DLG, DOM, DEM, DRG, DSM, etc.) and other spatial information data. On the basis of these studies, many provinces and cities have completed the coordinate system transformation of surveying and mapping results in China. This paper expounds the method of transforming the existing reference coordinate system into the geocentric coordinate system, summarizes and sorts out the common quality problems in the process of different data and different methods, and analyses the causes of the problems and the impact on the transforming results. Based on the above work, The paper provides reference and suggestions for the transforming work, which is aimed to improve the transformation quality in the future.

ASSESSMENT OF INFLUENCE OF IMAGE PROCESSING ON FULLY AUTOMATIC UAV PHOTOGRAMMETRY

Abstract. Nowadays UAVs have been widely used for large scale surveying and mapping. Compared with traditional surveying techniques, UAV photogrammetry is more convenient, cost-effective, and responsive. Aerial images, Position and Orientation System (POS) observations and coordinates of ground control points are usually acquired during a surveying campaign. Aerial images are the data source of feature point extraction, dense matching and ortho-rectification procedures. The quality of the images is one of the most important factors that influence the accuracy and efficiency of UAV photogrammetry. Image processing techniques including image enhancement, image downsampling and image compression are usually used to improve the image quality as well as the efficiency and effectiveness of the photogrammetric data processing. However, all of these image processing techniques bring in uncertainties to the UAV photogrammetry. In this work, the influences of the aforementioned image processing techniques on the accuracy of the automatic UAV photogrammetry are investigated. The automatic photogrammetric data processing mainly consists of image matching, relative orientation, absolute orientation, dense matching, DSM interpolation and orthomosaicing. The results of the experiments show that the influences of the image processing techniques on the accuracy of automatic UAV photogrammetry are insignificant. The image orientation and surface reconstruction accuracies of the original and the enhanced images are comparable. The feature points extraction and image matching procedures are greatly influenced by image downsampling. The accuracies of the image orientations are not influenced by image downsampling and image compression at all.

PRECISION POTENTIAL OF UNDERWATER NETWORKS FOR ARCHAEOLOGICAL EXCAVATION THROUGH TRILATERATION AND PHOTOGRAMMETRY

Abstract. Given the rise and wide adoption of Structure from Motion (SfM) and Multi View Stereo (MVS) in underwater archaeology, this paper investigates the optimal option for surveying ground control point networks. Such networks are the essential framework for coregistration of photogrammetric 3D models acquired in different epochs, and consecutive archaeological related study and analysis. Above the water, on land, coordinates of ground control points are determined with geodetic methods and are considered often definitive. Other survey works are then derived from by using those coordinates as fixed (being ground control points coordinates considered of much higher precision). For this reason, equipment of proven precision is used with methods that not only compute the most correct values (according to the least squares principle) but also provide numerical measures of their precisions and reliability. Under the water, there are two options for surveying such control networks: trilateration and photogrammetry, with the former being the choice of the majority of archaeological expeditions so far. It has been adopted because of ease of implementation and under the assumption that it is more reliable and precise than photogrammetry.This work aims at investigating the precision of network establishment by both methodologies by comparing them in a typical underwater archaeological site. Photogrammetric data were acquired and analysed, while the trilateration data were simulated under certain assumptions. Direct comparison of standard deviation values of both methodologies reveals a clear advantage of photogrammetry in the vertical (Z) axis and three times better results in horizontal precision.

An automatically connected graph representation based on B-splines for structural topology optimization

This paper introduces an automatically connected graph representation for structural topology optimization. Structural members of optimal topologies are constructed based on a graph whose each edge is represented by a B-spline curve with varying thickness. A square matrix including connective coefficients with either 0 or 1 is first proposed to automatically determine the way of linking two vertices of an edge. This significantly improves the flexibility of searching optimal topologies. Additionally, resulting designs are completely free from the checkerboard effect and grayscale without any filtering techniques. Control point coordinates of B-spline curves are considered as continuous design variables, while connective coefficients and thickness parameters are taken as discrete ones. Accordingly, this approach helps to reduce the total number of design variables considerably. Modified differential evolution (mDE), which is modified from original differential evolution (DE) to reduce computational cost but still guarantee the quality of solution, is proposed. mDE with the possibility of easily handling such variables and the capability of finding a global solution is utilized as an optimizer. The proposed method is essentially an intuitive method without a strong mathematical or theoretical background. Gained results are compared with other studies to verify the effectiveness of the present method.

Test Object for SEM Calibration: 2. Correlation Analysis of SEM Signals

A method for correlation analysis of the coordinates of control points in scanning electron microscope signals obtained by recording slow secondary electrons is described. The method allows one to independently and quantitatively estimate the fabrication quality of the relief components of test objects with a trapezoidal profile and large inclination angles of the lateral walls, which are intended for the calibration of a scanning electron microscope, and to choose only the components or separate areas of components with a high quality of their fabrication for the purpose of calibration. Correlation analysis of the quality of fabrication of the MShPS-2.0Si test object is performed. Analysis shows that the used microscopes (with real and usually unknown drawbacks) allow one to investigate the advantages and disadvantages both of real test objects with a trapezoidal profile and large inclination angles of the lateral walls, and of real scanning electron microscopes.

Accurate georeferencing of TLS point clouds with short GNSS observation durations even under challenging measurement conditions

Abstract The accuracy of georeferenced TLS point clouds is directly influenced by site-dependent GNSS effects, deteriorating the accuracy of the ground control point coordinate estimation. Especially under challenging GNSS conditions, this is a crucial problem. One common approach is to minimize these effects by longer observation durations, which in turn increases the effort in time and cost. In this paper, an algorithm is proposed that provides accurate georeferencing results, even under challenging measurement conditions and short observation durations. It iteratively improves the georeferencing accuracy by determining and applying obstruction adaptive elevation masks to the GNSS observations. The algorithm is tested and assessed using the data of a field test. It is demonstrated that after only 5 minutes observation duration, the ground control point coordinates can be estimated with an accuracy of 1 to 2 cm, independent from the GNSS measurement conditions. Initial states of the elevation masks are determined from a point cloud that is georeferenced using coordinates from a single point positioning solution, enhanced by a RAIM-FDE approach. Afterwards, the coordinates are estimated in a weighted least-squares baseline solution and both, the elevation masks and the coordinate estimation, are iteratively improved. Besides the significant reduction of measurement time, the proposed algorithm allows for increasing the amount of ground control points and can be applied to other direct or indirect GNSS-based georeferencing approaches.

STUDI ANALISIS KETELITIAN GEOMETRIK CITRA SATELIT RESOLUSI TINGGI SEBAGAI PETA DASAR RENCANA DETAIL TATA RUANG PERINDUSTRIAN (STUDI KASUS : KAWASAN PT SIER SURABAYA)

PT SIER region has an area of 245 ha. In addition, PT SIER region is divided into three sub-districts, namely Rungkut District, Tenggilis Mejoyo District, and Gunung Anyar Disrict. In the industrial area in the mapping of the region that have used a detailed map of a large scale is a scale of 1: 5000 or more. The remote sensing technology is needed for making the maps. Remote sensing technology is now used and applied in geoscience Indonesia for geospatial information on a local, regional, and globalThis research conducted data used for geometric correction is WorldView 2 satellite imagery with a spatial resolution of 2012 which is 0.46 meters and the Pleiades 1B in 2015 with a spatial resolution of 0.5 meters. In addition, the necessary data in this study are the coordinates of ground control points or so-called the Ground Control Point (GCP). The GCP coordinate data obtained from measurements in the field using geodetic GPS device. Measurements were performed using the static method for approximately 40 minutes. In doing geometric correction in this study using two methods, namely the transformation affine transformation and polynomial order 2 The results of this study indicate that the design of nets made to the GPS measurements have strength webs of 0.116274. The net strength has entered tolerance is ≤ 1. For the geometric correction to both images using two methods. In the method of affine value Root Mean Square Error (RMSE) for WorldView 2 is 0.306359 while the RMSE for the Pleiades 1B amounted to 0.319769. In order polynomial method 2, RMSE for WorldView 2 is 0.163263 while the RMSE for the Pleiades 1B amounted to 0.218205. The RMSE obtained both images can be used as a basis for making a map with a scale of 1: 5000

PRELIMINARY GAOFEN-3 INSAR DEM ACCURACY ANALYSIS

Abstract. GF-3 satellite, the first C band and full-polarization SAR satellite of China with spatial resolution of 1 m, was successfully launched in August 2016. We analyze the error sources of GF-3 satellite in this paper, and provide the interferometric calibration model based on range function, Doppler shift equation and interferometric phase function, and interferometric parameters calibrated using the three-dimensional coordinates of ground control points. Then, we conduct the experimental two pairs of images in fine stripmap I mode covering Songshan of Henan Province and Tangshan of Hebei Province, respectively. The DEM data are assessed using SRTM DEM, ICESat-GLAS points, and ground control points database obtained using ZY-3 satellite to validate the accuracy of DEM elevation. The experimental results show that the accuracy of DEM extracted from GF-3 satellite SAR data can meet the requirements of topographic mapping in mountain and alpine regions at the scale of 1 : 50000 in China. Besides, it proves that GF-3 satellite has the potential of interferometry.

The Use of GIS and Google Earth Images for Mapping of Taraba State University Campus


 
 
 
 A Campus guide map for Taraba State University Jalingo was produced. The data source for the study includes satellite images of the study area and field survey using a GPS device to collect coordinates of major ground control points. This research incorporated the use of geospatial techniques and functionalities such as georeferencing, digitizing and geo-database creation to generate a campus guide map. The findings of this study reviewed that most of the structures and roads are not adequately labeled or named for easy navigation. The study also showed that development is confined mostly to the North Western and southwestern part of the campus. We recommend structural planning and spatial development within the campus land cover in the future.
 
 
 
 

Life Cycle of Control Point Positions: A Case Study Using a Multi-State Control Point Database (MCPD)

The life-cycle (usability) of a control point's position is tied closely to the control point's stability, its datum, and velocity changes across a region due to crustal movement. Analyses of the coordinates of numerous control points stored in the Idaho and Montana Multi-State Control Point Database (<small>MCPD</small>) showed no statistical differences due to a point's stability and its physical setting. However, analyses comparing various realizations of horizontal datum revealed some significant differences. Specifically, there is >1 m difference observed between coordinates using <small>NAD</small> 83(1986) relative to <small>NAD</small>83(2011) and approximately 2 cm difference between <small>NAD</small> 83(CORS96) and <small>NAD</small> 83(2011) coordinates. A comparison of vertical coordinates derived from geoid models revealed a 30 cm mean difference between <small>GEOID</small>03 and <small>GEOID</small>12A, and >60 cm difference between <small>GEOID</small>99 and <small>GEOID</small>12A. The impact of velocity on these coordinates was apparent and varies strongly with local tectonics across the eastern Idaho study area. This study supports the <small>NGS</small> recommendation to use the most current realization of horizontal and vertical datum available.

Point Reg Net: Invariant Features for Point Cloud Registration Using in Image-Guided Radiation Therapy

In image-guided radiation therapy, extracting features from medical point cloud is the key technique for multimodality registration. This novel framework, denoted Control Point Net (CPN), provides an alternative to the common applications of manually designed keypoint descriptors for coarse point cloud registration. The CPN directly consumes a point cloud, divides it into equally spaced 3D voxels and transforms the points within each voxel into a unified feature representation through voxel feature encoding (VFE) layer. Then all volumetric representations are aggregated by Weighted Extraction Layer which selectively extracts features and synthesize into global descriptors and coordinates of control points. Utilizing global descriptors instead of local features allows the available geometrical data to be better exploited to improve the robustness and precision. Specifically, CPN unifies feature extraction and clustering into a single network, omitting time-consuming feature matching procedure. The algorithm is tested on point cloud datasets generated from CT images. Experiments and comparisons with the state-of-the-art descriptors demonstrate that CPN is highly discriminative, efficient, and robust to noise and density changes.

Accuracy analysis of 3D model obtained by photogrammetric method on the example of historic room from Wisłoujście Fortress

The article presents a comparison of obtained models of a test object. Close range photogrammetry was used to obtain 3D models. As test object was used one of the rooms located in Wisłoujście Fortress in Gdańsk, Poland. Different models were obtained by using different distribution and number of reference points. Article contains analysis of differences between coordinates of control points obtained from total station measurements and estimated from different 3D models.

Determination of Shift/Bias in Digital Aerial Triangulation of UAV Imagery Sequences

Currently UAV Photogrammetry is characterized a largely automated and efficient data processing. Depicting from the low altitude more often gains on the meaning in the uses of applications as: cities mapping, corridor mapping, road and pipeline inspections or mapping of large areas e.g. forests. Additionally, high-resolution video image (HD and bigger) is more often use for depicting from the low altitude from one side it lets deliver a lot of details and characteristics of ground surfaces features, and from the other side is presenting new challenges in the data processing. Therefore, determination of elements of external orientation plays a substantial role the detail of Digital Terrain Models and artefact-free ortophoto generation. Parallel a research on the quality of acquired images from UAV and above the quality of products e.g. orthophotos are conducted. Despite so fast development UAV photogrammetry still exists the necessity of accomplishment Automatic Aerial Triangulation (AAT) on the basis of the observations GPS/INS and via ground control points. During low altitude photogrammetric flight, the approximate elements of external orientation registered by UAV are burdened with the influence of some shift/bias errors. In this article, methods of determination shift/bias error are presented. In the process of the digital aerial triangulation two solutions are applied. In the first method shift/bias error was determined together with the drift/bias error, elements of external orientation and coordinates of ground control points. In the second method shift/bias error was determined together with the elements of external orientation, coordinates of ground control points and drift/bias error equals 0. When two methods were compared the difference for shift/bias error is more than ±0.01 m for all terrain coordinates XYZ.

Design of large-scale streamlined head cars of high-speed trains and aerodynamic drag calculation

Aerodynamic drag plays an important role in high-speed trains, and how to reduce the aerodynamic drag is one of the most important research subjects related to modern railway systems. This paper investigates a design method for large-scale streamlined head cars of high-speed trains by adopting NURBS theory according to the outer surface characteristics of trains. This method first created the main control lines of the driver cab by inputting control point coordinates; then, auxiliary control lines were added to the main ones. Finally, the reticular region formed by the main control lines and auxiliary ones were filled. The head car was assembled with the driver cab and sightseeing car in a virtual environment. The numerical simulation of train flow field was completed through definition of geometric models, boundary conditions, and space discretization. The calculation results show that the aerodynamic drag of the high-speed train with large-scale streamlined head car decreases by approximately 49.3% within the 50-300 km/h speed range compared with that of the quasi-streamlined high-speed train. This study reveals that the high-speed train with large-scale streamlined head car could achieve the purpose of reducing running aerodynamic drag and saving energy, and aims to provide technical support for the subsequent process design and production control of high-speed train head cars.

A WTLS-based rational function model for orthorectification of remote-sensing imagery

ABSTRACTThe rational function model (RFM) is widely applied to orthorectification of aerial and satellite imagery. This article proposes a new method named Ortho-WTLS to solve the RFM in remote-sensing imagery orthorectification. Based on a weighted total least squares (WTLS) estimator, the proposed method allows one to handle coordinates of ground control points (GCPs) that contain errors and are of unequal accuracies. This situation occurs, e.g. if GCPs are automatically selected. In the proposed model, first, the relationship of two linearization methods for an RFM with errors contained in GCPs is investigated and results in a hybrid linearization. Next, based on WTLS, RFM coefficients are estimated with an iterative computation function. Finally, the performance of the Ortho-WTLS method thus obtained is investigated using simulated images and remotely sensed images by collecting GCPs with varying errors. Experimental results show that the Ortho-WTLS method achieves a more robust estimation of model parameters and a higher orthorectification accuracy when compared with standard LS-based RFM estimation. We conclude that the quality of GCPs has a large impact on the accuracy and that an increasing number of low-precision GCPs may lead to a decrease in orthorectification quality.

Determining the Coordinates of Control Points in Hydrographic Surveying by the Precise Point Positioning Method

After Global Navigation Satellite Systems (GNSS) were first used in the field of hydrography in 1980, developments in hydrographic surveying accelerated. Survey precision in hydrography has been improved for both horizontal and vertical positioning and seafloor acoustic measurement by means of these new developments. Differential Global Positioning System (DGPS), Real Time Kinematic (RTK) and Network RTK (NRTK) techniques are the satellite-based positioning techniques that are commonly used in shallow water surveys and shoreline measurements. In line with these developments, the newer Precise Point Positioning (PPP) has been introduced. Combining precise satellite positions and clocks with dual-frequency GNSS data, PPP can provide position solutions from the centimetre to decimetre level. In this study, the coordinates of control points were determined by using the Post-Process PPP (PP-PPP) technique. Seven test points, which are the points of the Continuously Operating Reference Station - Turkey (CORS-TR) network, are selected near the shorelines within Turkey. The 24-hour data was split from one to six hours by one hour periods. Automatic Point Positioning Service (APPS) was selected to process the data. The poisoning error of the test points were given and compared with International Hydrographic Organization (IHO) S44 hydrographic survey standards.

DEM generation based on RPC model using relative conforming estimate criterion

A critical step in the Digital Elevation Model (DEM) generation is image georeferencing establishing sensor orientation, which is performed using ground control points. Geometric sensor models are used in image processing to model the relationship between object space and image space and to transform image data to conform to a map projection. There are two popular sensor models: the rigorous model and Rational Polynomial Coefficients (RPC) model. Using the RPC model has an advantage because users are not required to know specific information on the satellite sensors. A small number of inaccurate or unreliable source values of the Ground Control Point (GCP) coordinates can cause errors in computing the RPC model by traditional methods. Georeferencing requires accurate 3D ground coordinates, and our method can satisfy this requirement. We propose a new method of computing the RPC model using relative conforming estimate criterion.