FROM POINT SAMPLES TO SURFACES - ON MESHING AND ALTERNATIVES (original) (raw)
Related papers
2012
Terrestrial laser scanners deliver a dense point-wise sampling of an object’s surface. For many applications a surface-like reconstruction is required. The most typical example is the visualization of the scanned data. Traditional approaches use meshing algorithms to reconstruct and triangulate the surface represented by the points. Especially in cultural heritage, where complex objects with delicate structures are recorded in highly detailed scans, this process is not without problems. Often long and tedious manual clean-up procedures are required to achieve satisfactory results. After summarizing our experience with current meshing technology we therefore explore alternative approaches for surface reconstruction. An alternative approach presented within this paper is point splatting. We have developed an algorithm to compute a suitable surfel representation directly from the raw laser scanner data. This results in a speedy and fully automated procedure for surface reconstruction. ...
ADAPTIVE MESHING AND DETAIL-REDUCTION OF 3D-POINT CLOUDS FROM LASER SCANS
2000
D laser scanners become more and more popular especially for measuring construction sites, in the field of architecture and for preservation of monuments. As these scanners can only record discrete data sets (point clouds), it is necessary to mesh these sets for getting closed 3D models and take advantage of 3D graphics acceleration of modern graphics hardware. The meshing process
From point cloud to surface: modeling structures in laser scanner point clouds
Proceedings of the ISPRS …, 2007
The automatic modeling of precise structures from randomly distributed laser points derived from laser scanner data is a very hard problem, not completely solved and problematic in case of incomplete, noisy and sparse data. The generation of polygonal models that can satisfy high modeling and visualization demands is required in different applications, like architecture, archaeology, city planning, virtual reality applications and other graphics applications. The goal is always to find a way to create a computer model of an object which best fits the reality. Polygons are usually the ideal way to accurately represent the results of measurements, providing an optimal surface description. While the generation of digital terrain models has a long tradition and has found efficient solutions, the correct 3D modeling of closed surfaces or free-form objects is of recent nature, a not completely solved problem and still an important issue investigated in many research activities. In this paper we develop an approach for converting a laser scanner point cloud into a realistic 3D polygonal model that can satisfy high modeling and visualization demands. Close range photogrammetry deals since many years with manual or automatic image measurements. Now laser scanners are also becoming a standard source for input data in many application areas, providing millions of points. As a consequence, the problem of generating high quality polygonal models of objects from randomly distributed laser points is getting more and more attention. After reviewing some results in this context, we will describe a full approach for turning a usual unstructured point cloud into a consistent polygonal model. Finally, the polygonal model is turned into a hierarchical nodes network similar to VRML. A novel laserscanning processing tool, LSM3D (Laser Scanner Modeling 3D), has been developed and tested over different examples related with architectonic buildings.
Modeling and Visualization Objects from Point Cloud Data Surveyed With Terrestrial Laser Scanner
In this paper we present the problems of converting a measured point cloud surveyed with a terrestrial laser scanner into a realistic 3D polygonal model that can satisfy high modeling and visualization demands. Today 3D scanners are becoming a standard source for input data in many application areas, like architecture, archaeology and surveying. We convert a usually unstructured point cloud into a consistent polygonal model. We analyze the principal problems concerning the surface interpolation and the visualization modes of 3D objects. Finally we present the most popular software packages, languages and libraries used for visualization of point cloud data.
ISPRS Workshop 3D-ARCH: 3D virtual reconstruction and visualization of complex architectures, 2013
In Cultural Heritage field, the necessity to survey objects in a fast manner, with the ability to repeat the measurements several times for deformation or degradation monitoring purposes, is increasing. In this paper, two significant cases, an architectonical one and an archaeological one, are presented. Due to different reasons and emergency situations, the finding of the optimal solution to enable quick and well-timed survey for a complete digital reconstruction of the object is required. In both cases, two survey methods have been tested and used: a laser scanning approach that allows to obtain high-resolution and complete scans within a short time and a photogrammetric one that allows the three-dimensional reconstruction of the object from images. In the last months, several methodologies, including free or low cost techniques, have arisen. These kinds of software allow the fully automatically three-dimensional reconstruction of objects from images, giving back a dense point cloud and, in some case, a surfaced mesh model. In this paper some comparisons between the two methodologies above mentioned are presented, using the example of some real cases of study. The surveys have been performed by employing both photogrammetry and laser scanner techniques. The methodological operational choices, depending on the required goal, the difficulties encountered during the survey with these methods, the execution time (that is the key parameter), and finally the obtained results, are fully described and examinated. On the final 3D model, an analytical comparison has been made, to analyse the differences, the tolerances, the possibility of accuracy improvement and the future developments.
Proceedings of the …, 2009
Thanks to its speed and accuracy, terrestrial laser scanning is gaining importance in the field of architectural and cultural heritage. Laser scanners are field-of-view devices that offer a dense point-wise sampling of an object's geometry. The first part of this article addresses the question whether laser scanning produces sufficiently accurate results to be used for deformation monitoring of historical structures. A test setup using a masonry arch was prepared in which different scenarios were simulated. The structure was scanned at different times while moving one of its legs and the influence of different scan resolutions on the accuracy and the detectability of deformations were tested. Using a different setup, the influence on accuracy of different targets configurations, in particular orientations and distances to the scanner were tested. In a second part, two prototype algorithms are presented for the automatic generation of cross sections based on point clouds. The first method is based on point splats. Point splats are an alternative for meshes for the surface-like reconstruction of point clouds. Their main advantages are the low computational cost and the ability to give an accurate representation of sharp edges and details. The cross sections obtained from our algorithm are compared to similar cross sections obtained from a mesh based surface representation. The second proposed method segments a sliced point cloud into outlier-free clusters based on techniques from robust statistics. The cluster is grown by fitting a parametric model and computing the residuals using a moving least squares approach. This procedure generates a piecewise smooth cross-section with sharp discontinuity representations. In order to prove the usability of the algorithm, the cross sections obtained from this algorithm are compared to similar cross sections obtained from a mesh based surface representation.
Improving Completeness of Geometric Models from Terrestrial Laser Scanning Data
Geoinformatics FCE CTU, 2011
The application of terrestrial laser scanning for the documentation of cultural heritage assets is becoming increasingly common. While the point cloud by itself is sufficient for satisfying many documentation needs, it is often desirable to use this data for applications other than documentation. For these purposes a triangulated model is usually required. The generation of topologically correct triangulated models from terrestrial laser scans, however, still requires much interactive editing. This is especially true when reconstructing models from medium range panoramic scanners and many scan positions. Because of residual errors in the instrument calibration and the limited spatial resolution due to the laser footprint, the point clouds from different scan positions never match perfectly. Under these circumstances many of the software packages commonly used for generating triangulated models produce models which have topological errors such as surface intersecting triangles, holes...
Remote Sensing
Over the past few years, accurate 3D surface reconstruction using remotely-sensed data has been recognized as a prerequisite for different mapping, modelling, and monitoring applications. To fulfill the needs of these applications, necessary data are generally collected using various digital imaging systems. Among them, laser scanners have been acknowledged as a fast, accurate, and flexible technology for the acquisition of high density 3D spatial data. Despite their quick accessibility, the acquired 3D data using these systems does not provide semantic information about the nature of scanned surfaces. Hence, reliable processing techniques are employed to extract the required information for 3D surface reconstruction. Moreover, the extracted information from laser scanning data cannot be effectively utilized due to the lack of descriptive details. In order to provide a more realistic and accurate perception of the scanned scenes using laser scanning systems, a new approach for 3D reconstruction of planar surfaces is introduced in this paper. This approach aims to improve the interpretability of the extracted planar surfaces from laser scanning data using spectral information from overlapping imagery collected onboard modern low-cost aerial mapping systems, which are widely adopted nowadays. In this approach, the scanned planar surfaces using laser scanning systems are initially extracted through a novel segmentation procedure, and then textured using the acquired overlapping imagery. The implemented texturing technique, which intends to overcome the computational inefficiency of the previously-developed 3D reconstruction techniques, is performed in three steps. In the first step, the visibility of the extracted planar surfaces from laser scanning data within the collected images is investigated and a list of appropriate images for texturing each surface is established. Successively, an occlusion detection procedure is carried out to identify the occluded parts of these surfaces in the field of view of captured images. In the second step, visible/non-occluded parts of the planar surfaces are decomposed into segments that will be textured using individual images. Finally, a rendering procedure is accomplished to texture these parts using available images. Experimental results from overlapping laser scanning data and imagery collected onboard aerial mapping systems verify the feasibility of the proposed approach for efficient realistic 3D surface reconstruction.
3D OBJECT MODEL RECONSTRUCTION BASED ON LASER SCANNING POINT CLOUD DATA
Three dimensional (3D) reconstruction has been widely applied in urban planning, digital city, and the conservation of cultural/archaeological heritage etc. to re-build 3D object geometry. In the situation where the objects are irregular and have complex-structure, the use of conventional methods is time-consuming and mostly not practicable because of the workload involved and the detail of roofs or footprints cannot be modelled and low accuracy. The paper introduces the method of reconstructing 3D object model based on point clouds acquired by 3D terrestrial laser scanner including data acquisition, data processing, multiple scan registration, 3D modelling and texture mapping. The experiment result shows that, the method can effectively and quickly reconstruct 3D object geometry with many details, especially in 3D city model and cultural/archaeological heritage."
From point cloud to surface: the modeling and visualization problem
International Workshop on Visualization and Animation …, 2003
In this paper we address all the problems and solutions of converting a measured point cloud into a realistic 3D polygonal model that can satisfy high modeling and visualization demands. Close range photogrammetry deals since many years with manual or automatic image measurements. Now 3D scanners are also becoming a standard source for input data in many application areas, providing for millions of points. As a consequence, the problem of generating high quality polygonal meshes of objects from unorganized point clouds is receiving more and more attention. After reviewing the different 3D shape techniques for surface reconstruction, we will report the full process of converting a usually unstructured point cloud into a consistent polygonal model. Some triangulation algorithms, modeling methods and visualization techniques are also described and different examples are presented.