This paper describes a 3-d automated pavement distress data collection and analysis system based on NRC's Biris sensor technology. The paper introduces the problem to be solved, the selecteddesign criteria, and t...
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ISBN:
(纸本)0818679441
This paper describes a 3-d automated pavement distress data collection and analysis system based on NRC's Biris sensor technology. The paper introduces the problem to be solved, the selecteddesign criteria, and the adopted solution to monitor the quality of road surfaces. The system geometry for the acquisition of the three-dimensional coordinates of pavement surface distresses is presented. Multiple feature extraction and system integration concepts are given with emphasis placed on the real-time processing of the raw data by a parallel array of processors. Advantages anddisadvantages of this technology will be discussed. System performances and experimental results are provided.
Constructing a full CAd model of a part requires feature descriptions from all sides;in this case we consider surface patches as the geometric primitives. Most previous research in surface patch extraction has concent...
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ISBN:
(纸本)0818679441
Constructing a full CAd model of a part requires feature descriptions from all sides;in this case we consider surface patches as the geometric primitives. Most previous research in surface patch extraction has concentrated on extracting patches from a single view. This leads to several problems with aligning and combining partial patch fragments in order to produce complete part models. We have avoided these problems by adapting our single view, range data segmentation program to extract patches, and thus models, directly from fully merged range datasets.
We present in this paper a method to obtain automatically CAd models of industrial pipes from range images The models are based on two geometric primitives, cylinders and torii, which are enough to represent most part...
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ISBN:
(纸本)0818679441
We present in this paper a method to obtain automatically CAd models of industrial pipes from range images The models are based on two geometric primitives, cylinders and torii, which are enough to represent most parts of the pipes. The images are obtained with art accurate long-distance laser range sensor developed for reverse engineering in industrial structures. The key issue for automatic CAdmodeling is the automatic segmentation of the data into subsets of points corresponding to the desired primitives. To do so, we use differential geometry to segment lines of centers of curvature into straight and curved parts, corresponding to the cylinder and torus parts of the original image. differential geometry results being noisy and biased, we use an optimal approach for the computation of centers of curvature.
This paper presents an automatic method to trim arms from the surface scan data of the human body. Curve and surface approximation are employed to refill the data gap after the trimming process. This delivers a more r...
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This paper presents an automatic method to trim arms from the surface scan data of the human body. Curve and surface approximation are employed to refill the data gap after the trimming process. This delivers a more realistic torso model for further applications.
A method for the automatic reconstruction of 3d objects from multiple camera views for 3d multimedia applications is presented. Conventional 3d reconstruction techniques use equipment that restrict the flexibility of ...
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ISBN:
(纸本)0818679441
A method for the automatic reconstruction of 3d objects from multiple camera views for 3d multimedia applications is presented. Conventional 3d reconstruction techniques use equipment that restrict the flexibility of the user. In order to increase this flexibility, the presented method is characterized by a simple measurement environment, that consists of a new calibration pattern placed below the object allowing object and pattern acquisition simultaneously. This ensures, that each view can be calibrated individually. From these obtained calibrated camera views, a textured3d wireframe model is estimated using a shape-from-silhouette approach and texture mapping of the original camera views. Experiments with this system have confirmed a significant gain of flexibility for the user and a drastic reduction of costs for technical equipment while ensuring comparable model quality as conventional reconstruction techniques at the same time.
The paper presents an approach for building 3-d city models for virtual environments from multiple 3-ddata sets acquired from different viewpoints by light striping. The raw data sets are represented as single valued...
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ISBN:
(纸本)0818679441
The paper presents an approach for building 3-d city models for virtual environments from multiple 3-ddata sets acquired from different viewpoints by light striping. The raw data sets are represented as single valued parametric surfaces called the 3-d profile maps. The profile maps are registered to the same coordinate system by an iterative surface matching algorithm developed previously. The registration proceeds hierarchically from lour to high resolution and all the data sets are matched simultaneously but an initial registration is assumed to be known. After having segmented each map by a region growing algorithm, the maps are integrated into a piecewise planar surface model by merging compatible segments in the overlapping areas. The borders of the segments are also traced on the parametric domains of the maps as a step for building a wireframe model. Test results are shown in the cease of a scale model of an urban area digitized in laboratory conditions.
This paper describes recognition of the 3-d pose and shape of articulated objects like a human hand and visual tracking of moving persons from a sequence Of images. In the first stage of pose and shape recognition, ro...
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ISBN:
(纸本)0818679441
This paper describes recognition of the 3-d pose and shape of articulated objects like a human hand and visual tracking of moving persons from a sequence Of images. In the first stage of pose and shape recognition, rough estimation of the pose is obtained by silhouette matching to a rough model of a hand and fingers. In the second stage, the model is refined using restrictions of the shape and pose of the object. Modifying the extended Kalman filter so as to satisfy the restrictions, the depth ambiguity is gradually resolved from observed images. Next, a method is proposed for tracking an object from the optical flow anddepth data acquired from a sequence of stereo images. A target region is extracted by Baysian inference in term of the optical flow, disparity and the predicted target location. Occlusion of the target can also be detected from the abrupt change of the disparity of the target region. Realtime human tracking in, a real image sequence is shown.
We propose a method to generate a facial caricature depending on a simple method for corresponding 3-d facial images. In this method, we extract several facial parts regions each of which include facial parts of the f...
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ISBN:
(纸本)0818679441
We propose a method to generate a facial caricature depending on a simple method for corresponding 3-d facial images. In this method, we extract several facial parts regions each of which include facial parts of the face by using both gray and range images. The diagonal corners of the respective extracted regions are used to provide the informations on the correspondence between the faces. Therefore, by using this method, it is expectable to reduce the number of the feature points for the correspondence from more than several hundreds to ten or so. Ar the same time, this method make it possible to extract boundaries of facial parts. In order to examine the feasibility of this method, we employ a usual corresponding method of the triangular patch as the reference. We generated the 3-d mean face and3-d facial caricature to demonstrate experimentally the feasibility of the proposed method, It was clarified that the number of the correspondence points can be reduced to only 10% of the usual method.
In this paper an optical configuration based on autosynchronized laser scanning is proposed for the 3d measurement of road surfaces. The advantages of this technique over classical triangulation methods are exposed. T...
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ISBN:
(纸本)0818679441
In this paper an optical configuration based on autosynchronized laser scanning is proposed for the 3d measurement of road surfaces. The advantages of this technique over classical triangulation methods are exposed. The road inspection system developed at the National Optics Institute (NOI) using this type of laser telemetry is also presented. This system uses two autosynchronized laser scanners in order to obtain transverse 3d and intensity profiles of road surfaces. Also described are simple algorithms which detect and measure rutting and cracking conditions. Results include rut measurements on both real and simulated3d road profiles and a crack map of an actual pavement section.
We present a new method for the global registration of several overlapping three-dimensional (3d) surfaces sampled on an object. The method is based on the ICP algorithm and on a segmentation of the unstructured sampl...
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ISBN:
(纸本)0818679433;0818679441
We present a new method for the global registration of several overlapping three-dimensional (3d) surfaces sampled on an object. The method is based on the ICP algorithm and on a segmentation of the unstructured sampled points in an optimized set of z-buffers. This multi-z-buffer technique provides a 3d space partitioning which allows the registration process to detect quickly all the overlapping surfaces and to concentrate on them even when the surfaces overlap each other only slightly. It also greatly accelerates the search of the nearest neighbours in the establishment of the point-to-point correspondence between two overlapping surfaces. Then a randomized iterative registration is processed on the surface set. We have tested an implementation of this technique on real sampled surfaces. It appears to be rapid, accurate and robust, especially in the case of highly curved objects. (C) 1999 Elsevier Science B.V. All rights reserved.
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