جستجوی مقالات مرتبط با کلیدواژه "نواحی پنهان" در نشریات گروه "عمران"

For complete 3D modeling of a desired area, using by terrestrial laser scanner point cloud, it is necessary moving the set and increase the occupation points to measure the occlusions. But it takes more time and money for field measurements and in result will be increased time and calculations cost. Thus, the initial planning for selecting the optimal locations for the device in order to complete 3D model is essential and the computing field and office costs in a reasonable period decreased. In this paper, particle swarm optimization algorithm to achieve this objective has been used. In the proposed method, an approximate model of the scan region needs for the candidate deployment positions, and makes the algorithm’s search space. Each particle is set of the selected candidate points and a set of particles is considered as a groups. Cost function was considered with two goals, a reduction in occlusions and pick a least possible number of selected points. Algorithms starts with a set of multiple random selection of points, as an initial response and moving particles in the search space, during successive iterations, the algorithm answers locating the optimal laser scanner. In this process, the optimal choice system is automatic and repetitive and ensure proper alignment with the minimum number of points required for a complete measurement of region is achieved. The results show that the particle swarm optimization algorithm in a large number of the candidate can optimize the laser scanner selected points for the establishment.

Terrestrial Laser Scanner (TLS) technology, have altered quickly data acquisition for map production in surveying. In many cases, it is impossible to complete surveying of the desired area without TLS displacement in one station to another. Occlusion is innate in data acquisition, with this type of device. To solve this problem, TLS devices should be placed in different locations and scanning operation to be performed. Increase the number of scan stations cause data redundancy and on the other hand will be increases the computational and monetary cost of project. Aim of this paper is presents a novel method for selecting a better place and localization of TLS. Thus, the mechanism of data acquisition was considered by TLS. Also parameters affecting the choice of a place and a station were investigated. Point cloud data investigations show that these parameters have a major impact in reducing the time needed to completeness of data collection. Occlusion as one of the most important parameters has been discussed in this paper. Using data from one station with combination of image processing method, the area of hidden parts to be estimated. Due to the size and area of the various occlusion set, determines to be appropriate locations for new data collection station. After evaluating candidate points according to given criteria, conditional on the project, the next point will be selected for acquisition. By continuous using this method, reduce a ground operation volume in this type of projects. Reducing time of land surveying in many field projects is very important. While ensuring the quality of data and decreased project costs is essential.