Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

IEEE Transactions on Pattern Analysis and Machine Intelligence

A novel method, µ-MAR, able to both coarse and fine register 3D point sets.The method overcomes noisy data problem using model based planes registration.µ-MAR iteratively registers a 3D markers around the object to be reconstructed.It uses a variant of the multi-view registration with subsets of data.Transformations to register the markers allow to reconstruct the object accurately. Many applications including object reconstruction, robot guidance, and. scene mapping require the registration of multiple views from a scene to generate a complete geometric and appearance model of it. In real situations, transformations between views are unknown and it is necessary to apply expert inference to estimate them. In the last few years, the emergence of low-cost depth-sensing cameras has strengthened the research on this topic, motivating a plethora of new applications. Although they have enough resolution and accuracy for many applications, some situations may not be solved with general state-of-the-art registration methods due to the signal-to-noise ratio (SNR) and the resolution of the data provided. The problem of working with low SNR data, in general terms, may appear in any 3D system, then it is necessary to propose novel solutions in this aspect. In this paper, we propose a method, µ-MAR, able to both coarse and fine register sets of 3D points provided by low-cost depth-sensing cameras, despite it is not restricted to these sensors, into a common coordinate system. The method is able to overcome the noisy data problem by means of using a model-based solution of multiplane registration. Specifically, it iteratively registers 3D markers composed by multiple planes extracted from points of multiple views of the scene. As the markers and the object of interest are static in the scenario, the transformations obtained for the markers are applied to the object in order to reconstruct it. Experiments have been performed using synthetic and real data. The synthetic data allows a qualitative and quantitative evaluation by means of visual inspection and Hausdorff distance respectively. The real data experiments show the performance of the proposal using data acquired by a Primesense Carmine RGB-D sensor. The method has been compared to several state-of-the-art methods. The results show the good performance of the µ-MAR to register objects with high accuracy in presence of noisy data outperforming the existing methods.

µ-MAR

This paper presents a new approach for recognition of 3D objects that are represented as 3D point clouds. We introduce a new 3D shape descriptor called Intrinsic Shape Signature (ISS) to characterize a local/semi-local region of a point cloud. An intrinsic shape signature uses a view-independent representation of the 3D shape to match shape patches from different views directly, and a view-dependent transform encoding the viewing geometry to facilitate fast pose estimation. In addition, we present a highly efficient indexing scheme for the high dimensional ISS shape descriptors, allowing for fast and accurate search of large model databases. We evaluate the performance of the proposed algorithm on a very challenging task of recognizing different vehicle types using a database of 72 models in the presence of sensor noise, obscuration and scene clutter.

Intrinsic shape signatures: A shape descriptor for 3D object recognition

Scan registration is an essential sub-task when building maps based on range finder data from mobile robots. The problem is to deduce how the robot has moved between consecutive scans, based on the ...

/pdf/scan-registration-for-autonomous-mining-vehicles-using-3d-vjm5066ql4.pdf

Scan registration for autonomous mining vehicles using 3D-NDT

A method is presented that uses an approximate nearest neighbor method for determining correspondences within the iterative closest point algorithm. The method is based upon the k-d tree. The standard k-d tree uses a tentative backtracking search to identify nearest neighbors. In contrast, the approximate k-d tree (Ak-d tree) applies a depth-first nontentative search to the k-d tree structure. This search improves runtime efficiency, with the tradeoff of reducing the accuracy of the determined correspondences. This approximate search is applied to early iterations of the iterative closest point algorithm, transitioning to the standard k-d tree for the final iterations after the change in the mean square error of the correspondences becomes sufficiently small. The method benefits both from the improved time performance of the approximate search in early iterations as well as the full accuracy of the complete search in later iterations. Experimental results indicate that the time efficiency of Ak-d tree is superior to the k-d tree and Elias for moderately large point sets. The change in the shape of the minimum potential well space is subtle, and the convergence properties are often identical. In those cases where the global minimum was not achieved, the difference in final mse was very small. In one trial, Ak-d tree converged faster to a better minimum with a smaller mse, which indicates that the use of approximate methods may be beneficial in the presence of outliers.

/pdf/approximate-k-d-tree-search-for-efficient-icp-3k6r9woa5o.pdf

Approximate k-d tree search for efficient ICP

A novel multi-scale operator for unorganized 3D point clouds is introduced. The Difference of Normals (DoN) provides a computationally efficient, multi-scale approach to processing large unorganized 3D point clouds. The application of DoN in the multi-scale filtering of two different real-world outdoor urban LIDAR scene datasets is quantitatively and qualitatively demonstrated. In both datasets the DoN operator is shown to segment large 3D point clouds into scale-salient clusters, such as cars, people, and lamp posts towards applications in semi-automatic annotation, and as a pre-processing step in automatic object recognition. The application of the operator to segmentation is evaluated on a large public dataset of outdoor LIDAR scenes with ground truth annotations.

Difference of Normals as a Multi-scale Operator in Unorganized Point Clouds

A method is provided for detecting a collision between a robot and one or more obstacles before it occurs The robot is modeled by spheres in a voxelized workspace Each voxel within the workspace is assigned a value which corresponds to its distance from the closest obstacle A collision is determined to be imminent if the voxel value at the centre of a sphere is less than the radius of the sphere in voxels

Real time collision detection

A novel solution is presented to the Nearest Neighbor Problem that is specifically tailored for determining correspondences within the Iterative Closest Point Algorithm. The reference point set P is preprocessed by calculating for each point p/spl I.oarr//sub i//spl isin/P that neighborhood of points which lie within a certain distance /spl epsiv/ of p/spl I.oarr//sub i/. The points within each /spl epsiv/-neighborhood are sorted by increasing distance to their respective p/spl I.oarr//sub i/. At runtime, the correspondences are tracked across iterations, and the previous correspondence is used as an estimate of the current correspondence. If the estimate satifies a constraint, called the Spherical Constraint, then the nearest neighbor falls within the /spl epsiv/-neighborhood of the estimate. A novel theorem, the Ordering Theorem, is presented which allows the Triangle Inequality to efficiently prune points from the sorted /spl epsiv/-neighborhood from further consideration. The method has been implemented and is demonstrated to be more efficient than both the k-d tree and Elias methods. After /spl sim/40 iterations, fewer than 2 distance calculations were required on average per correspondence, which is close to the theoretical minimum of 1. Furthermore, after 20 iterations the time expense per iteration was demonstrated to be negligibly more than simply looping through the points.

Michael Greenspan

Papers

Approximate k-d tree search for efficient ICP

Difference of Normals as a Multi-scale Operator in Unorganized Point Clouds

Real time collision detection

A nearest neighbor method for efficient ICP

Local shape descriptor selection for object recognition in range data