Coordinates Of Control Points Research Articles

Evaluation of Combined Phase Ambiguity Solution Method on GPS Assisted Aerial Triangulation.

Aerial triangulation, in which the transformation parameters of central projection are solved from observed photograph coordinates of orientation points and ground control points using the least square method, has become a popular technology in the field of topographical survey by the help of computers. On the other hand, the process of field survey to establish photo signals (control point survey) has been remained as a laborious work (Ackermann, 1990) . Recently, the technology to utilize the coordinates of the aerial camera at each shot given by kinematic GPS observation into aerial triangulation has been developed, and thus the number of required photo signals can be dramatically reduced. In this paper, the authors compared two methods of GPS-assisted aerial triangulation with conventional methods. Namely, early established Shift Drift method and a newly developed Combined Phase Ambiguity Solution (CPAS) method are compared with Bundle and Independent Model adjustment methods. Also, a trial case to implement a block adjustment without any ground control points using CPAS method will be discussed.

Shape structural optimization with an interior point nonlinear programming algorithm

The aim of this paper is to study the implementation of an efficient and reliable technique for shape optimization of solids, based on general nonlinear programming algorithms. We also study the practical behaviour for this kind of applications of a quasi-Newton algorithm, based on the Feasible Direction Interior Point Method for nonlinear constrained optimization. The optimal shape of the solid is obtained iteratively. At each iteration, a new shape is generated by B-spline curves and a new mesh is automatically generated. The control point coordinates are given by the design variables. Several illustrative two-dimensional examples are solved in a very efficient way. We conclude that the present approach is simple to formulate and to code and that our optimization algorithm is appropriate for this problem.

An Anisotropic Spatial Modeling Approach for Remote Sensing Image Rectification

Rectification of a remote sensing image is commonly done by applying polynomial regression models to image coordinates and map coordinates of ground control points. A major drawback of the polynomial regression model is that it does not capture the random characteristic of terrain elevation. In fact, the distortion of a remote sensing image is attributed to the variation of terrain elevation and orbital parameters, the variations being random in nature. A more effective approach of remote sensing image rectification is a stochastic approach that takes into account the spatial variation structure of terrain elevation. This article presents an anisotropic spatial modeling approach of image rectification using ordinary kriging estimation. By considering the residuals of polynomial trend mapping as anisotropic random fields, the proposed approach models separately the spatial variation structures of the residuals in X and Y directions, and employs the ordinary kriging method for spatial interpolation of the residual random fields. By means of a cross validation procedure, residuals of image rectification by the polynomial trend mapping, the multiquadric interpolation function, and the ordinary kriging approaches are compared. The ordinary kriging approach yields smallest variances and root-mean-squared of mapping errors.

Creation of DEM Using Wild B8-S Aviograph Connected to EK-22 Digitizing System

In this paper the accuracy of the Wild B8-S aviograph analogue stereoplotter connected to Wild EK-22 Data Acquisition System was tested for providing data to create a digital elevation model (DEM). Two stereomodels of photography of scale 1.14000 and 1:40000 covering a rugged terrain were sequentially oriented in the plotter. Digital model coordinates of ground control points together with those of check points were input for analytical absolute orientation program. Planimetric accuracy obtained was 5 micrometers for the first model and 11 micrometers for the second model, at photo scale. Height accuracy upon which the accuracy of DEM depends was 0.02 percent and 0.01 percent of the flying height for the two models, respectively.

An Interactive Pattern Making and 3D Simulation System of Collars.

In this paper, collars are classified into three basic types - stand-collar, roll-collar and open-collar according to their structure. A geometrical model is established to simulate these collars and methods of drafting patterns are considered too. The collar shape was modeled as three-dimensional Bezier patches. Changing the position of control points of these patches can interactively control the collar shape. Triangular surface developing method is employed to make the pattern for stand-collar. For roll-collar and open-collar, flat pattern method using the data calculated from three-dimensional coordinates of control points are employed. With these methods, an interactive collar designing system is developed to simulate collars and automatically make patterns. Considering practical usage, we reproduced three types of collars with the patterns drafted by the system, and observed these reproductions congruent with simulated ones well. It is demonstrated to be more reliable, efficient and accurate than the method of handwork.

The optimum die profile for the cylindrical bending of plates

This paper presents a methodology for the design of plate-forming dies in cylindrical bending using optimization techniques to reduce the cost of die production by reducing the trial-and-error procedure considerably in determining the final die geometry. The plate thickness is discretized by plane-strain finite-elements. The die is taken to be rigid and its profile is approximated by Bezier curves the control-point coordinates of which are the design variables. The die profile is varied to minimize the difference between the required shape and the shape of the bent plate, considering springback action. The unconstrained optimization problem is solved by the BFGS (Broyden-Fletcher-Goldfarb-Shanno) method. A numerical example is presented where the optimum die profile is obtained for a plate bent into a quarter circle.

Model-Based Detection and Localization of Circular Landmarksin Aerial Images

The photogrammetric exploitation of aerial images essentially requires the accurate reconstruction of the imaging geometry. This especially includes the determination of the orientation of the camera. Usually, the orientation parameters are determined by spatial resection, knowing the exact coordinates of control points on the ground and in the image. The reliability and accuracy of this registration task strongly depend on the selection of suitable landmarks as well as on the precision obtained for landmark localization. In this contribution, we consider the problem of automatic landmark extraction for the purpose of aerial image registration. We suggest to use manhole covers as a specific type of circular landmarks which frequently occur in urban environments and we introduce a model-based approach for localizing these features with high subpixel precision. Our approach is based on a parametric intensity model. Localization of the landmarks is done by directly fitting this model to the observed image intensities. Since we have an explicit description of the landmark it is possible to verify the result by exploiting the estimated parameters. We also address the problem of landmark detection which can greatly be supported by template matching. The template used is a prototype model which is generated from representative examples during a training phase. The training scheme also provides initial values for the fitting procedure as well as thresholds for the final verification step. The full approach has been tested on synthetic as well as on real image data.

An adaptive method for image registration

The paper deals with the registration of images with non-linear local geometric distortions. It describes a new approach to the determination of a mapping function from given coordinates of control points. The processed image is recursively divided into subregions of various size and shape according to the distortion character. Each subregion is then transformed by a simple local transformation. The described method enables the registration with optional accuracy. A practical use of this method is presented and a comparison of its accuracy and computing complexity with previously published methods is given.

Application of statistical testing to cadastral survey traverses

In cadastral survey practice the “ratio” method is commonly used to determine whether or not a given measured traverse is acceptable. The method, however, does not take into account estimated standard deviations (random errors) of traverse observations (angles, distances and in some cases coordinates) or traverse geometry. In this paper the authors propose that a statistical test of the misclosure replace the “ratio” method. The test will indicate, at a chosen confidence level, whether or not a given traverse misclosure should be accepted. All computations required to apply the method are given and two examples are presented to show how the method is applied. Because the method can take into account estimated random errors of coordinates, it is well suited for application to traverses within control networks in which coordinates of control points have previously been established by satellite, inertial, photogrammetric, ground survey or combined methods.

Planar control in multi-camera calibration for 3-D gait studies

The complexity of camera calibration has been a dominant limitation to whole-body movement studies in 3-D, especially in regard to the requirements on a calibration distribution in object-space. This paper focuses on photogrammetric calibration of a given camera configuration in which the usual requirement of a 3-D calibration object with known control point coordinates (“absolute control”) is circumvented. A calibration plane containing a 2-D distribution of known control points is placed at various globally defined positions and attitudes throughout the observation field, thus constituting a 3-D partial control distribution with the object-space coordinate system defined by one of these positions and attitudes; the unknown parameters of the remaining planes are solved for simultaneously with those of the cameras. The efficacy of the procedure is evaluated in terms of the relative influences of calibration and observation errors on dynamic target position reconstruction. Assuming equal error levels of the raw image data in calibration and reconstruction, the influence of the former may be rendered negligibly small using three exposures of 10–20 control points each.

Star-calibrated lunar photography by method of separate plates for a determination of the coordinates of lunar control points

A photographic determination of the absolute coordinates of lunar features against the stellar background by the method of separated plates is proposed. The description of the technique and the equation for the plates reduction is given. The determination of the stars positions by new technique is given in the description of the method.

Calibration of 35 pic-du-midi photographs of the moon

The measured and calibrated coordinates of selenodetic control points on 35 Pic-du-Midi negatives obtained by the method of star-calibrated lunar photography (cf. Moutsoulas, 1970) are presented in this paper.

An operational theory of laser-radar selenodesy

A theory of the utilization of laser techniques for ranging from the Earth to the Moon for the purpose of providing control points on the lunar surface at which the figure of the Moon is measured to an accuracy at least an order of magnitude better than that of the present astrometric measurements is presented. This, in turn, increases the accuracy of the horizontal selenocentric coordinates of topographical features measured by present astrometric methods. The improvement in the vertical and horizontal coordinates of control points in the Apollo landing zone will aid in the analysis of Unmanned Lunar Orbiter photographs for the selection of Apollo landing sites. The present discussion proposes the means of obtaining the ground control upon which the Orbiter photogrammetry is to be fastened. In addition, a technique of combining Goldstone tracking data to show where the resulting lunar figure is positioned relative to the Moon's center of mass is presented. If corner reflectors are placed on the lunar surface, as suggested by many members of the scientific community, or on a lunar orbiting vehicle, one or more Earth-based laser ranging systems are essential. These reflectors will give enough enhancement in return signal to allow for an additional increase in range accuracy of one to two orders of magnitude. In addition to the primary data on the figure of the Moon, a number of other measurements of scientific importance are then readily obtainable. As far as the measurement of control points is concerned, however, the use of corner reflectors is not essential for the success of this project. Questions regarding the influence on the present shape of the Moon of the frozen tide, isostasy, and past impacts of large asteroids appear in large part answerable through the data which are indicated to be obtainable under the present theory.