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Edge Detectors (edge + detector)
Selected Abstracts3D Image Segmentation of Aggregates from Laser ProfilingCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 4 2003Hyoungkwan Kim Automated scanners of different designs use cameras or lasers to obtain digital images of groups of aggregate particles. To accurately determine particle size and shape parameters, each particle region in the image must be isolated and processed individually. Here, a method for segmenting a particle image acquired from laser profiling is developed using a Canny edge detector and a watershed transformation. Canny edges with rigorous and liberal threshold values are used to outline particle boundaries on a binary image and to check the validity of watersheds, respectively. To find appropriate regional minima in the watershed transformation, a varying search window method is used, where the number of neighboring pixels being compared with the pixel of interest is determined from the height value of the pixel. Test results with this method are promising. When implemented in automated systems that are designed to rapidly assess size and shape characteristics of stone particles, this technique can not only reduce the amount of time required for aggregate preparation, but also increase the accuracy of analysis results. [source] Three-dimensional localization of thin-walled sheet metal parts for robotic assemblyJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 5 2002Edward J. Park This article presents a technical demonstration of a system for determining the three-dimensional spatial location of complexly shaped, thin-walled sheet metal parts grasped by robots during assembly. For successful part assembly, the precise location of grasped parts (essential for successful mating of parts) must be achieved. A localization system is implemented to determine the accurate position and orientation of a sheet metal part that has been picked up by a robot from an arbitrary location. The proposed localization system employs a novel sensing method, utilizing laser-based proximity and edge detectors, to extract the part feature data in real time. These geometrical feature data are incorporated into an existing localization algorithm, which is based on the singular value decomposition formulation of the part localization problem. The sensing method is particularly effective in measuring 3-D feature geometry (i.e., thin edges) of sheet metal parts. An experimental single-robot test bed has been developed to demonstrate the feasibility of the part localization concept for a single sheet metal part. The experimental results obtained from the test bed demonstrate that the system can be effectively used for the localization of thin-walled sheet metal parts. © 2002 Wiley Periodicals, Inc. [source] Determination of grave locations in Dedemezari Necropolis (Western Turkey) using magnetic field derivativesARCHAEOLOGICAL PROSPECTION, Issue 4 2008A. Büyüksaraç Abstract The location of the study area for this research of a Middle Bronze Age Necropolis is situated in the west of Turkey near Afyonkarahisar. Magnetic surveying was carried out in two adjacent areas (Areas 4 and 5). Four trenches have been excavated so far and graves were located in positions interpreted from a magnetic survey carried out in 2005. Initial excavations have shown that cist, pithos and simple graves were placed randomly and it is suggested that Dedemezari Necropolis is similar to the well known necropoleis of Gordion and Sariket. This paper compares the results of some phase-based filters which show improved performance as edge detectors in different ways. The filters are demonstrated on synthetic magnetic data and magnetic field data from Dedemezari Necropolis. Magnetic field derivatives, both vertical and horizontal, are common and useful tools for interpretation of the magnetic anomalies. Interpretation of magnetic field derivatives, separately or together, provide images of shallow bodies from magnetic data. The horizontal derivatives of the total magnetic field were computed in the space domain by means of finite-difference relationships, and the vertical derivative was computed in the frequency domain by using fast Fourier transform filtering. Derivatives of the magnetic anomalies have been used for detection of causative bodies. The analytic signal (AS), the enhanced horizontal derivative (EHD), tilt derivative (TD), theta map, hyperbolic tilt angle (HTA) and total horizontal derivative (THDR) methods were applied not only to synthetic anomalies but also to the measured magnetic anomalies of Areas 4 and 5. However, AS and EHD produced the best results as the other methods created edge effects. Copyright © 2008 John Wiley & Sons, Ltd. [source] Interval type-2 fuzzy logic for edges detection in digital imagesINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 11 2009Olivia Mendoza Edges detection in a digital image is the first step in an image recognition system. In this paper, we show an efficient edges detector using an interval type-2 fuzzy inference system (FIS-2). The FIS-2 uses as input the original images after applying Sobel filters and attenuation filters, then the fuzzy rules infer normalized values for the edges images, especially useful to enhance the performance of neural networks. To illustrate the results, we built frequency histograms of some images and compare the results of the FIS-2 edge's detector with the gradient magnitude method and a type-1 fuzzy inference system (FIS-1). The FIS-2 results are better than the gradient magnitude and FIS-1, because the edges preserve more detail of the original images, and the backgrounds are more homogeneous than with FIS-1 and the gradient's magnitude method. © 2009 Wiley Periodicals, Inc. [source] | ||||||||||