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Proceedings of SPIE - The International Society for Optical Engineering (1996756X)3957pp. 398-402
Virtual Reality (VR) is a possible which brings users to the reality by computer and Virtual Environment (VE) is a simulated world which takes users to any points and directions of the object. VR and VE can be very useful if accurate and precise data are used, and allows users to work with realistic model. Photogrammetry is a technique which is able to collect and provide accurate and precise data for building 3D model in a computer. Data can be collected from various sensors and cameras, and methods of data collector are vary based on the method of image acquiring. Indeed VR includes real-time graphics, three-dimensional model, and display and it has application in the entertainment industry, flight simulators, industrial design. Above definitions describe the relationship between VR and VE with photogrammetry. This paper describes a reliable and precis method of data acquiring based on close range photogrammetry for building a VR model. The purpose of this project is to make a real possibility for seismic designers to investigate all effects of shaking on a real building. Minar Gonban is an ancient building with two amazing minarets at Esfehan IRAN. While one of them was shaken the second one started to shake. The project is fulfilled on this building because building simply can be shaken and its effects can be investigated. The building was photographed by multiple movie cameras and photo cameras. Sequence images were restored in a computer for creating sequence models of building. A VR model is builded based on extracted data from photogrammetry images. The developed VR model is precise and reliable and provides real possibility for users to investigate the effects of shaking on the building. The developed VR model is based on real data. The results verify a reliable VR can be useful for human life because one of its application can help to investigate effects of earthquake on the building and duce its casualty.
It is possible to use single frequency GPS receivers to estimate the Total Electron Content (TEC). In this research, we improved an algorithm presented by Giffard [2], that is based on a least squares solution. We investigated the effect of the use of different weights (elevation of satellites, signal to noise ratio, combination of elevation and signal to noise ratio) and different block sizes on TEC estimates. We found that these parameters had a significant impact on TEC estimates based on this algorithm. Our research is based on observations at the GPS site of the Esfahan University made with single frequency 12-channel Leica System 500 receivers.
CTIT workshop proceedings series (16821750)37pp. 823-827
In this paper we present and develop a set of algorithms, mostly based on morphological operators, for automatic colonic polyp detection applied to computed tomography (CT) scans. Initially noisy images are enhanced using Morphological Image Cleaning (MIC) algorithm. Then the colon wall is segmented using region growing followed by a morphological grassfire operation. In order to detect polyp candidates we present a new Automatic Morphological Polyp Detection (AMPD) algorithm. Candidate features are classified as polyps and non-polyps performing a novel Template Matching Algorithm (TMA) which is based on Euclidean distance searching. The whole technique achieved 100% sensitivity for detection of polyps larger than 10 mm and 81.82% sensitivity for polyps between 5 to 10 mm and expressed relatively low sensitivity (66.67%) for polyps smaller than 5 mm. The experimental data indicates that our polyp detection technique shows 71.73% sensitivity which has about 10 percent improvement after adding the noise reduction algorithm.
Advanced Materials Research (discontinued) (16628985)301pp. 388-396
Cyclic axial loads in steel tubular might lead to local buckling, wrinkling and accumulation of plastic strains in the tube. During their life time steel tubes may also experience different types of material loss such as corrosion or thinning. This paper deals with the effects of corrosion defects on the strain ratcheting response of steel tubes. Small scale un-corroded and corroded tubular specimens have been tested under monotonic and cyclic axial loads. Optical system ATOS has been used for 3D surface acquisition and reconstruction of the tested specimen and to evaluate their strain ratcheting and wrinkling response. This is a camera-based triangulation system. A processing unit employs optical transform equations to automatically and with a great accuracy calculate 3D coordinates for every pixel of camera. Depending on camera resolution as an effect of such a scan a cloud of up to 4 million points has been obtained for every single measurement. From the results, it has been noticed that the possibility of ratcheting or progressive plastic failure substantially increases by the presence of the corrosion defects. With the corroded specimens, the strain ratcheting behaviour in the defected zone has been distinctively different from that in the perfect zones.
Journal of the Earth and Space Physics (2538371X)37(1)pp. 11-24
The least squares harmonic estimation is applied to the hourly time-series of Total Electron Contents (TEC) derived from ionospheric models using seven years of GPS observations processed by Bernese software. The frequencies of dominant spectral components in the spectrum are estimated. We observe significant periodic patterns with periods of 24 h and its fractions 24h/n, n=2,.,11, which are the well-known Fourier series decomposition of the diurnal periodic pattern of the ionospheric variations. The principal component with daily signal is due to the day-night variation of TEC values. The semidiurnal and tri-diurnal components can be explained by the substorm signatures in both auroral electrojet (in layer E) and ring current variations (related to magnetosphere at low latitudes) and tidal effects. Also, the spectrum shows the well-known 27-day period of solar cycle variations. We observe annual, semi-annual and tri-annual signals in the series. The detected signals are then applied to perform an ionospheric prediction. The results indicate that a substantial part (in the absolute sense) of the TEC values can be predicted using this base function, and an undetectable part remains as disturbed noise which can exceed 20 TEC units for the disturbed ionosphere. In comparison with the standard Klobuchar model, the model presented in this contribution will significantly improve the single frequency GPS positioning accuracy.
Sattari, M., Shahbazi, M., Homayouni, S., Saadatseresht, M., Shahbazi, M., Sattari, M., Homayouni, S., Saadatseresht, M.
2025 29th International Computer Conference, Computer Society of Iran, CSICC 2025pp. 148-155
This paper describes a method for detecting and recognizing traffic signs by integrating the range and intensity images of a Time-of-flight camera, based on Photonic Mixer Device (PMD) technology, with images of a standard digital camera. The reflectivity of signs surfaces along with background suppression ability and active sensing of the PMD camera make the signs sharply visible in intensity images. Besides the image descriptors, utilizing the object-based information provides robust and reliable detection and recognition. The overall acquisition system and proposed technique overcome the conventional illumination, disorientation and scaling problems in detection and recognition process. The method of this paper is implemented and evaluated on data acquired by a multi-sensor mobile mapping system.
Sattari, M., Shahbazi, M., Homayouni, S., Saadatseresht, M., Shahbazi, M., Sattari, M., Homayouni, S., Saadatseresht, M.
CTIT workshop proceedings series (16821750)39pp. 51-56
Recent advances in positioning techniques have made it possible to develop Mobile Mapping Systems (MMS) for detection and 3D localization of various objects from a moving platform. On the other hand, automatic traffic sign recognition from an equipped mobile platform has recently been a challenging issue for both intelligent transportation and municipal database collection. However, there are several inevitable problems coherent to all the recognition methods completely relying on passive chromatic or grayscale images. This paper presents the implementation and evaluation of an operational MMS. Being distinct from the others, the developed MMS comprises one range camera based on Photonic Mixer Device (PMD) technology and one standard 2D digital camera. The system benefits from certain algorithms to detect, recognize and localize the traffic signs by fusing the shape, color and object information from both range and intensity images. As the calibrating stage, a self-calibration method based on integrated bundle adjustment via joint setup with the digital camera is applied in this study for PMD camera calibration. As the result, an improvement of 83% in RMS of range error and 72% in RMS of coordinates residuals for PMD camera, over that achieved with basic calibration is realized in independent accuracy assessments. Furthermore, conventional photogrammetric techniques based on controlled network adjustment are utilized for platform calibration. Likewise, the well-known Extended Kalman Filtering (EKF) is applied to integrate the navigation sensors, namely GPS and INS. The overall acquisition system along with the proposed techniques leads to 90% true positive recognition and the average of 12 centimetres 3D positioning accuracy.
CTIT workshop proceedings series (16821750)40(1W3)pp. 453-458
Determination of the maximum ability for feature extraction from satellite imageries based on ontology procedure using cartographic feature determination is the main objective of this research. Therefore, a special ontology has been developed to extract maximum volume of information available in different high resolution satellite imageries and compare them to the map information layers required in each specific scale due to unified specification for surveying and mapping. ontology seeks to provide an explicit and comprehensive classification of entities in all sphere of being. This study proposes a new method for automatic maximum map feature extraction and reconstruction of high resolution satellite images. For example, in order to extract building blocks to produce 1:5000 scale and smaller maps, the road networks located around the building blocks should be determined. Thus, a new building index has been developed based on concepts obtained from ontology. Building blocks have been extracted with completeness about 83%. Then, road networks have been extracted and reconstructed to create a uniform network with less discontinuity on it. In this case, building blocks have been extracted with proper performance and the false positive value from confusion matrix was reduced by about 7%. Results showed that vegetation cover and water features have been extracted completely (100%) and about 71% of limits have been extracted. Also, the proposed method in this article had the ability to produce a map with largest scale possible from any multi spectral high resolution satellite imagery equal to or smaller than 1:5000.
