Model Registration Control Point Set Selection for Turbine Blade Shape Inspection

2009 ◽  
Vol 45 (11) ◽  
pp. 240 ◽  
Author(s):  
Yunyong CHENG
Keyword(s):  
Turbine Blade ◽  
Control Point ◽  
Blade Shape ◽  
Point Set ◽  
Selection For ◽  
Shape Inspection

scholarly journals Direct Georeferencing for the Images in an Airborne LiDAR System by Automatic Boresight Misalignments Calibration

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5056
Author(s):  
Haichi Ma ◽  
Hongchao Ma ◽  
Ke Liu ◽  
Wenjun Luo ◽  
Liang Zhang
Keyword(s):  
Control Point ◽  
Digital Camera ◽  
Iteration Process ◽  
Airborne Lidar ◽  
Image Point ◽  
Test Field ◽  
Lidar System ◽  
Ground Control Points ◽  
Source Data ◽  
Point Set

Airborne Light Detection and Ranging (LiDAR) system and digital camera are usually integrated on a flight platform to obtain multi-source data. However, the photogrammetric system calibration is often independent of the LiDAR system and performed by the aerial triangulation method, which needs a test field with ground control points. In this paper, we present a method for the direct georeferencing of images collected by a digital camera integrated in an airborne LiDAR system by automatic boresight misalignments calibration with the auxiliary of point cloud. The method firstly uses an image matching to generate a tie point set. Space intersection is then performed to obtain the corresponding object coordinate values of the tie points, while the elevation calculated from the space intersection is replaced by the value from the LiDAR data, resulting in a new object point called Virtual Control Point (VCP). Because boresight misalignments exist, a distance between the tie point and the image point of VCP can be found by collinear equations in that image from which the tie point is selected. An iteration process is performed to minimize the distance with boresight corrections in each epoch, and it stops when the distance is smaller than a predefined threshold or the total number of epochs is reached. Two datasets from real projects were used to validate the proposed method and the experimental results show the effectiveness of the method by being evaluated both quantitatively and visually.

scholarly journals Fast georeferencing/geocoding tool for old maps with large distortions

2019 ◽  
Vol 1 ◽  
pp. 1-1
Author(s):  
Mátyás Gede
Keyword(s):  
Web Application ◽  
Control Point ◽  
Control Points ◽  
Point Pair ◽  
Web Map ◽  
Old Maps ◽  
Local Interpolation ◽  
Automatic Placement ◽  
Point Set ◽  
Map Objects

<p><strong>Abstract.</strong> Maps created before the 17th century often have large distortions which make it useless to force them into any modern map projection by georeferencing. In a local scope, however, they preserve spatial relationships between map objects, therefore, using an appropriate control point set and local interpolation it is possible to define a quite accurate connection between the old and a modern map.</p><p> Additionally, researchers in the past decades created long lists of settlements of these maps, often without any geometric information but matching most places with present day settlements.</p><p> The author developed a web application to help geocoding these lists and at the same time to create an accurate georeferenced of the corresponding old maps. This tool displays the old map and a recent web map parallel, without forcing the projection of the web map to the old one. The user can load settlement lists, perform a bulk geocoding based on present day names. The geocoded places appear on the new map, and any of these points can be also placed on the old map, defining a control point pair. After setting enough control points, all the other place names can be automatically placed by local interpolation based on the control points. The place positions can be refined manually by the user, which will improve the accuracy of the automatic placement as well.</p>

Parameterization of a Multi-Directional Tidal Turbine Performance Using Computational Fluid Dynamics

2015 ◽  
Author(s):  
Richard B. Medvitz ◽  
Michael L. Jonson ◽  
James J. Dreyer ◽  
Jarlath McEntee
Keyword(s):  
Turbine Blade ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Moving Mesh ◽  
Cfd Analysis ◽  
Two Dimensional ◽  
Peak Efficiency ◽  
Trailing Edge ◽  
Blade Shape ◽  
Tidal Turbine

High resolution RANS CFD analysis is performed to support the design and development of the Ocean Renewable Power Company (ORPC) TidGen™ multi-directional tidal turbine. Two-dimensional and three-dimensional unsteady, moving-mesh CFD is utilized to parameterize the device performance and to provide guidance for device efficiency improvements. The unsteady CFD analysis was performed using a well validated, naval hydrodynamic CFD solver and implementing dynamic overset meshes to perform the relative motion between geometric components. This dynamic capability along with the turbulence model for the expected massively separated flows was validated against published data of a high angle of attack pitching airfoil. Two-dimensional analyses were performed to assess both blade shape and operating conditions. The blade shape performance was parameterized on both blade camber and trailing edge thickness. The blades shapes were found to produce nearly the same power generation at the peak efficiency tip speed ratio (TSR), however off-design conditions were found to exhibit a strong dependency on blade shape. Turbine blades with the camber pointing outward radially were found to perform best over the widest range of TSR’s. In addition, a thickened blade trailing edge was found to be superior at the highest TSR’s with little performance degradation at low TSR’s. Three-dimensional moving mesh analyses were performed on the rotating portion of the full TidGen™ geometry and on a turbine blade stack-up. Partitioning the 3D blades axially showed that no sections reached the idealized 2D performance. The 3D efficiency dropped by approximately 12 percentage points at the peak efficiency TSR. A blade stack-up analysis was performed on the complex 3D/barreled/twisted turbine blade. The analysis first assessed the infinite length blade performance, next end effects were introduced by extruding the 2D foil to the nominal 5.6m length, next barreling was added to the straight foils, and finally twist was added to the foils to reproduce the TidGen™ geometry. The study showed that making the blades a finite length had a large negative impact on the performance, whereas barreling and twisting the foils had only minor impacts. Based on the 3D simulations the largest factor impacting performance in the 3D turbine was a reduction in mass flow through the turbine due to the streamlines being forces outward in the horizontal plane due to the turbine flow resistance. Strategies to mitigate these 3D losses were investigated, including adding flow deflectors on the turbine support structure and stacking multiple turbines in-line.

Curve and Surface Representation by Iterative B-Spline Fit to a Data Point Set

1987 ◽  
Vol 16 (1) ◽  
pp. 29-35 ◽  
Author(s):  
Marilyn Lord
Keyword(s):  
Computer Aided Design ◽  
Control Point ◽  
The Body ◽  
B Spline ◽  
B Splines ◽  
Spline Surface ◽  
Data Points ◽  
Point Set ◽  
Support Surfaces ◽  
Aided Design

The method of B-splines provides a very powerful way of representing curves and curved surfaces. The definition is ideally suited to applications in Computer Aided Design (CAD) where the designer is required to remodel the surface by reference to interactive graphics. This particular facility can be advantageous in CAD of body support surfaces, such as design of sockets of limb prostheses, shoe insoles, and custom seating. The B-spline surface is defined by a polygon of control points which in general do not lie on the surface, but which form a convex hull enclosing the surface. Each control point can be adjusted to remodel the surface locally. The resultant curves are well behaved. However, in these biomedical applications the original surface prior to modification is usually defined by a limited set of point measurements from the body segment in question. Thus there is a need initially to define a B-spline surface which interpolates this set of data points. In this paper, a computer-iterative method of fitting a B-spline surface to a given set of data points is outlined, and the technique is demonstrated for a curve. Extension to a surface is conceptually straightforward.

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