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Author(s): 

ZOLFAGHARI M. | MALIAN A.

Journal: 

AMIRKABIR

Issue Info: 
  • Year: 

    2002
  • Volume: 

    13
  • Issue: 

    50
  • Pages: 

    77-85
Measures: 
  • Citations: 

    0
  • Views: 

    308
  • Downloads: 

    0
Abstract: 

Historical buildings and ancient monuments are valuable cultural heritage of nations, that are unfortunately being damged due to human interference, weather conditions and environmental pollution. So, it is necessary to record all of them in a rapid and easy manner, in order that archaeological studies and establishment of a National Heritage Archive becomes i possible. Close Range Photogrammetry (CRP) with interesting and unique capabilities is the most useful tool for this purpose. The difficulty in traditional Photogrammetry is the necessity of metric camera that is expensive, hard to access (especially in countries such as Iran that are rich in cultural heritage), far from user - friendliness and needs special processing instruments. Such factors reduce the degree of usefulness and easiness of CRP technology. There are a lot of historical monuments in Iran (which many of them are in the level of the most important cultural heritage of the world) and in the present project one of them i.e. the relief of Driush I, the Great (500 B. C.) on the rocks of Bisotun was choosen as the test field. This splendid monument is, nationally and internationally, highly discussed and there is an Emergent propgramme in hand for its conservation and restoration. The present project is concentrated on the application of professional and amateur non metric cameras. These cameras have unknown calibration parameters that are usually photo variant. The kernel of ths research is firsty to have a survey on the calibration elements of non metric cameras (that are easily available) and secondly to show the photogrammetric capabilities of a precise non metric (Hasselblad), an amateur (Yashica), and a digital (Minolta) camera from the stereoplotting and rectification point of view.

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Issue Info: 
  • Year: 

    2024
  • Volume: 

    2
  • Issue: 

    1
  • Pages: 

    1-10
Measures: 
  • Citations: 

    0
  • Views: 

    205
  • Downloads: 

    65
Abstract: 

Background and Objectives: The urbanization occurs everywhere, especially in developing countries and is the process of changing the social order and transforming the landscape of a city. However, urbanization always leads to the growth of slums or informal settlements. The development of urban areas with dense and complex slum areas requires extensive planning and very accurate and reliable information. The process of collecting data using traditional methods is time-consuming and expensive.Methods: Remote sensing is used to identify, identify and monitor slum settlements in space and time and better understand the physical effects of slums. But due to the complexities of the slum areas and the spatial resolution of satellite images, it is not possible to use satellite images to prepare accurate maps with high details. With the emergence of unmanned aerial vehicle (UAV) as an imaging platform and the use of these images for aerial photogrammetric mapping of UAVs, its applications in various fields have increased day by day. Due to their portability, accuracy, low cost, and high imaging speed, UAVs have attracted attention in many research fields to obtain the latest information about target areas. Due to the use of non-metric cameras in UAV Photogrammetry, camera calibration is necessary is carried out in the UAV image processing software using the bundle adjustment technique. However, the conventional aerial Photogrammetry imaging structure, i.e. obtaining vertical images with overlaps, due to the dependence between the camera calibration parameters and the external orientation parameters of the camera, cannot achieve high accuracy in the 3D maps. In addition, due to the low height of UAV images, more hidden areas are created in the 3D photogrammetric model. In this research, vertical and oblique UAV images with angles of 30 and 45 degrees were used to prepare a three-dimensional map of the slum area with high density and complexity, and the accuracy of the vertical and oblique images was evaluated using control points in the study area.Findings:  The high resolution of UAV images and the generated orthomosaic makes it possible to recognize details and provides a better understanding of the earth's features. For example, walls with a thickness of ten centimeters and power lines with a thickness of two centimeters can be seen. As a result, urban planners can determine the boundaries of buildings with high accuracy and produce cadastral maps with high accuracy. Oblique images are distinguished by a wider field of view than vertical images. It is also possible to see areas hidden under obstacles such as plants, buildings and narrow alleys. This feature provides high accuracy that can be used in projects that require detailed descriptions, such as cultural heritage protection projects and urban projects that require details such as building facades and height estimates.Conclusion: In this research, vertical and oblique UAV images were used to prepare a 3D map of the slum area, and based on the results, the total error of oblique images is 6.2 and 8.3 cm for oblique images with angles of 30 and 45 degrees, respectively. While the total error of vertical images is equal to 16.1 cm. This comparison shows the superiority of the accuracy of oblique images compared to vertical images.

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Author(s): 

Maryam Jahangiri Maryam Jahangiri, Sayed Shojaedin Shayegh Sayed Shojaedin Shayegh

Issue Info: 
  • Year: 

    2025
  • Volume: 

    14
  • Issue: 

    1
  • Pages: 

    1-7
Measures: 
  • Citations: 

    0
  • Views: 

    14
  • Downloads: 

    0
Abstract: 

This comprehensive review study examines Photogrammetry as a digital imaging technique in modern dentistry. Photogrammetry, using multiple images from various angles, can accurately determine the position of objects in space and create highly accurate three-dimensional models. This technique, initially developed for industrial and mapping applications, is now increasingly used in digital dentistry. This article reviews the Photogrammetry method, the types of devices used (intraoral and extraoral), and its clinical applications in various dental fields, including implantology, orthodontics, and maxillofacial surgery. It also addresses the advantages and limitations of this technique, including accuracy, speed, cost, and ease of use. The results of this review show that Photogrammetry, as an accurate and efficient imaging method, can help improve the quality of digital dental treatments. The high accuracy of Photogrammetry enables precise recording of the position of implants, teeth, and facial structures and can contribute to the predictability and accuracy of treatments. The introduction of portable intraoral and extraoral Photogrammetry devices has made access to this technology easier in dental offices and has made it possible to benefit from its advantages in everyday clinical conditions. Overall, Photogrammetry is emerging as a powerful tool in digital dentistry and can help improve the accuracy, efficiency, and predictability of dental treatments. However, further research is needed to more accurately investigate the factors affecting the accuracy of Photogrammetry and evaluate its clinical applications in real-world conditions.

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Issue Info: 
  • Year: 

    2018
  • Volume: 

    19
  • Issue: 

    4 (75)
  • Pages: 

    81-93
Measures: 
  • Citations: 

    0
  • Views: 

    1085
  • Downloads: 

    0
Abstract: 

Background and Objective: Accurate estimation of forest biomass for assessment of the potential of forests to sequester atmospheric carbon is an important aspect in forest management. The present study aimed to estimate the biomass of single-stem Quercus brantii trees by using terrestrial Photogrammetry as a nondestructive method.Method: The study was conducted in Chaharmahal and Bakhtiari province. First, 32 individual trees from different diameter classes were selected and two photos were taken for each tree in perpendicular directions. Then, the scale of each photo was calculated and the volume of different components of trees was determined (trunk, main branches, branches and foliage (Crown)). Density of each component was measured using data collected from field and laboratory analysis; and biomass of each component was measured. Estimated biomass from terrestrial Photogrammetry method was compared with the actual biomass obtained from the field method.Findings: Results showed that there is no significant difference between the terrestrial Photogrammetry method and the field method, which is accurate method in order to evaluate biomass.Discussion and Conclusions: This study showed that terrestrial Photogrammetry for estimation of above ground biomass for single-stem Quercus brantii trees is an accurate and efficient method.

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Issue Info: 
  • Year: 

    2018
  • Volume: 

    7
  • Issue: 

    4
  • Pages: 

    15-24
Measures: 
  • Citations: 

    0
  • Views: 

    1255
  • Downloads: 

    0
Abstract: 

Although close range Photogrammetry has not been a common approach in the Civil Engineering field especially the displacement monitoring of large scale constructions، many project successfully used this approach and as a result this method have a high potential in this application. Nowadays، as a result of improving the computer vision and Photogrammetry techniques implemented in many software and high resolution images captured by the off-the-shelf digital cameras، the use of progressive photogrammetric techniques instead of traditional displacement methods become more resendable. This paper aims to explain a novel method for monitoring of the large scale constructions based on visual inspection. This method can specify the displacement of the constructions based on photogrammetric and computer vision methods using drones. The evaluation of the proposed system is done on long wall in two epochs with a short time interval. Having known the zero displacement for this construction، the difference between the coordinates of some sample points obtained in first epoch and the second epoch، 1. 89 mm، shows the accuracy of the proposed system in detecting displacement. Moreover، the accuracy of this photogrammetric method was investigated by developing a tool which manually provides a known displacement between two points in the second epoch. The displacements of these points were estimated using the proposed method and compared with the known displacement. The accuracy for this method، less than 2 mm، can confirm the capability of this method for such applications.

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Issue Info: 
  • Year: 

    2022
  • Volume: 

    13
  • Issue: 

    1
  • Pages: 

    87-100
Measures: 
  • Citations: 

    0
  • Views: 

    160
  • Downloads: 

    40
Abstract: 

A proper understanding of the shear behaviour of rock joints and discontinuities is yet a remaining challenge in the rock engineering research works owing to the difficulties in quantitatively describing the joint surface roughness both at the field and the laboratory scales. Several instruments and techniques have been developed over the years for the surface characterisation of joints at the field-and laboratory-scale investigations, amongst which the application of the Photogrammetry methods has obtained a growing popularity. This work evaluates the applicability of the Photogrammetry techniques for the characterisation of joint surface topography and texture at micro-scales, which has been largely understudied in the literature. Three tensile joint surfaces are digitized using Photogrammetry, and the results are compared with those obtained from laser scans with a high 3D accuracy. A comprehensive statistical analysis is then undertaken on the digitized point clouds in order to assess the performance of Photogrammetry in surface characterisation. The results of this work show that the height differences between the resulting point clouds from the two adopted techniques (Photogrammetry and 3D laser scanning) follow the normal distribution with the mean values close to zero. The statistical analyses illustrate that the measured joint surfaces using the Photogrammetry techniques are in good agreement with the laser scanning data, confirming that Photogrammetry is a capable method for characterising the joint surface roughness even at micro-scales. Interestingly, the results obtained further indicate that the accuracy and preciseness of the Photogrammetry techniques are independent from the joint roughness coefficient but the camera and configuration parameters remarkably control the performance of the measurement.

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Author(s): 

Ghanbari Parmehr Ebadat

Issue Info: 
  • Year: 

    2019
  • Volume: 

    8
  • Issue: 

    3
  • Pages: 

    32-39
Measures: 
  • Citations: 

    0
  • Views: 

    1347
  • Downloads: 

    0
Abstract: 

Measurement and experimental analysis of stress and strain of enforced objects are crucial in the fields of mechanics and civil engineering. The photoelasticity as a conventional method for measurement and analysis suffers from some limitations such as the need for specific transparent material, appropriate equipment and enough experience. In this research, Photogrammetry was introduced for the experimental analysis of stress and strain measurement because of its high accuracy, ease and independence to the material of the object. To compare the accuracy of Photogrammetry and photoelasticity, a crane hook-shaped object from Araldite epoxy was tested for different enforcement. In each step, in addition to recording the required information for photoelasticity, photos of the object were taken by a digital camera in a fixed position and orientation. The positions of the corresponding points on the object were measured with an accuracy of 0. 01 pixel using digital image processing and least square image matching techniques. The measured stress and strain using photoelasticity and Photogrammetry were compared with analytical stress and strain measurement method. The results indicated high accuracy for Photogrammetry compared to photoelasticity. Therefore, conventional methods for stress and strain measurements can be replaced by Photogrammetry.

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Issue Info: 
  • Year: 

    2021
  • Volume: 

    7
  • Issue: 

    4
  • Pages: 

    639-651
Measures: 
  • Citations: 

    0
  • Views: 

    78
  • Downloads: 

    11
Abstract: 

This study aims to estimate the different two-and three-dimensional characteristics seedlings using terrestrial close-range Photogrammetry. Three-dimensional models were prepared using images taken by a smartphone camera and the process of “Structure from Motion with Multi View Stereo Photogrammetry” (SfM-MVS). To evaluate the accuracy of the obtained results, characteristics such as diameter at the middle height of stem, height, crown height, crown diameter, stem volume, crown volume and total volume of each seedling were measured. According to the RMSE% and the calculated Bias% (less than 10%), the images and model used to estimate the two-dimensional characteristics of seedlings, had factual accuracy. Also, among the three-dimensional characteristics of the seedlings, the highest and lowest accuracy related to stem volume with R2 = 0. 89, RMSE% = 23. 08% and crown volume with R2= 0. 67, RMSE% = 31. 92% respectively. Overall, it can be concluded that the images taken by the smartphone camera and the SfM-MVS method used in this study have remarkable accuracy to estimate characteristics of seedling such as diameter at the middle height of stem, height, crown height, crown diameter and stem volume, However, it is not accurate enough to estimate the crown volume characteristic‎.

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Author(s): 

Issue Info: 
  • Year: 

    2022
  • Volume: 

    38
  • Issue: 

    13
  • Pages: 

    3018-3026
Measures: 
  • Citations: 

    1
  • Views: 

    19
  • Downloads: 

    0
Keywords: 
Abstract: 

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Journal: 

GEOGRAPHICAL DATA

Issue Info: 
  • Year: 

    2021
  • Volume: 

    30
  • Issue: 

    117
  • Pages: 

    65-78
Measures: 
  • Citations: 

    0
  • Views: 

    528
  • Downloads: 

    0
Abstract: 

Introduction: Recently, cadastre has become a suitable platform for global partnership in management of land and its assets. Due to ever-increasing population, spatial organization of citiesis considered to be one of the most important issues in national development planning. This indicates the necessity of using 3D land information systems since theenvironment, quality, ownership and other benefits of lands do not only change horizontallyany moreand height is also a decisive and vital factor. Therefore, 3D cadastreis used as abasis for integrating information into a complete and efficient information storage system. This system is usedtomanage scarce land resources and plays a key role in achieving future legal and managerial success in the field ofreal-estate. Designing and implementing a system capable of displaying the third dimension (height) is very complex. Common methods of producing 3D cadastral models include land surveying, classical aerial Photogrammetry, high-resolution satellite imagery, and so on. Recently, the advent of drones has provided a suitable platform for large-scale cadastral mapping. Collecting high resolution images, processing withstructure from motion(SFM) method, multi-stereo vision (MSV), and dense 3D point cloud with a high resolution of about a few centimeters are the main advantages of these tools. Recentstudies in this field indicate high capabilities of UAV-based Photogrammetry method for the production and updating of cadastral maps. Materials and Methods: Due to the applied nature of the present study, guideline for the spatial information production using photogrammetric method published by Tehran Municipality and other Surveying and Mapping guidelines published by the National Cartographic Center of Iran have been used to produce 3D cadastral modeland reach relatively real Results: . The study area is Khosban village in MiyanTaleqan rural district, in the central district of Taleqan County, Alborz Province, Iran. Necessary information was collected using an eBee Plus survey drone with a SODA camera (designed for professional photogrammetric applications). Besides, exterior orientation parameters were measured using the preciseinertial measurement unit (IMU), global navigation satellite system (GNSS) Antenna withreal-time kinematic (RTK) and post-processing kinematic (PPK) techniques and triangulation was performed using these parameters. To increase the accuracy, reduce hidden areas and achieve more accurate 3D models, 75%longitudinal and transverse overlappingwere considered for the images. Image processing was performed using Pix4dmapper and Metashape software and products such as orthomosaic, dense 3D point cloud, and digital surface model were produced. To prove thegeometric accuracy of triangulation, 8 ground control points were used, and32 checkpoints were also used for the final evaluation of 3D models. Results: and Discussion: 3D cadastre implementation was performedin the present paperusing UAV based Photogrammetry without any ground control points. According to the Results: of triangulation, the maximum root mean square error in the X-component was reported 3. 21 cm, the Y-componentwas reported2. 86 cm, and the Z-component was reported 3. 96 cm using Pix4dmapper and Metashape software. Moreover, 32 sample checkpoints were used for the final evaluation of the 3D models and data collected from these points were compared with the reference data. Results: indicated the occurrence of maximum root mean square error in the horizontal components (X, Y) of 0. 2 and 0. 21 meter respectively, and 0. 27 meter in the height component (Z). A correlation coefficient of about 1 represents high geometric accuracy of the 3D models produced using UAV based Photogrammetry. Conclusion: 3D cadastre can be used as a tool for improving land management and related issues. Due to structural complexity and ownership issues, most developed countrieshave not yet fully implemented 3D cadastre. However, these countries are always looking for ways to achieve such a system. So far in our country, the issue of 3D cadaster has only been pursued in academic studies and no practical stephas been taken to implement this system. Unfortunately, technical dimension and preparation of 3D models are only a part of 3d cadastre and legal issues occurring due to insufficient understanding of the third dimensionand its complexity alsolead to failure in the implementation of 3D cadaster.

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