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Mapping Forest Structure Using UAS inside Flight Capabilities
摘要： We evaluated two unmanned aerial systems (UASs), namely the DJI Phantom 4 Pro and DJI Mavic Pro, for 3D forest structure mapping of the forest stand interior with the use of close-range photogrammetry techniques. Assisted flights were performed within two research plots established in mature pure Norway spruce (Picea abies (L.) H. Karst.) and European beech (Fagus sylvatica L.) forest stands. Geotagged images were used to produce georeferenced 3D point clouds representing tree stem surfaces. With a flight height of 8 m above the ground, the stems were precisely modeled up to a height of 10 m, which represents a considerably larger portion of the stem when compared with terrestrial close-range photogrammetry. Accuracy of the point clouds was evaluated by comparing field-measured tree diameters at breast height (DBH) with diameter estimates derived from the point cloud using four different fitting methods, including the bounding circle, convex hull, least squares circle, and least squares ellipse methods. The accuracy of DBH estimation varied with the UAS model and the diameter fitting method utilized. With the Phantom 4 Pro and the least squares ellipse method to estimate diameter, the mean error of diameter estimates was ?1.17 cm (?3.14%) and 0.27 cm (0.69%) for spruce and beech stands, respectively.
关键词： point cloud,diameter at breast height (DBH),photogrammetry,obstacle sensing,forestry,unmanned aerial system (UAS),vision positioning system
更新于2025-09-23 15:23:52
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Methodology for diagnosing crack patterns in masonry structures using photogrammetry and distinct element modeling
摘要： Understanding the causes of damages on existing structures can augment preservation, renovation, and rehabilitation efforts. The aim of this work is to outline a method for diagnosing the most probable causes of cracks on existing structures using a combination of photogrammetry and distinct element modeling (DEM). Five experimental, masonry walls were constructed and cracked; the state of the wall before and after cracking was recorded using photogrammetry. Using distinct element modeling, each test wall was subjected to a variety of loading conditions including the same load case which was used to crack the wall during experimental testing. The crack patterns in the simulations were compared to the experimental crack patterns using a combined qualitative and quantitative method. The simulation which most closely reflected the existing damage patterns was selected as the most probable cause of the damages. For each of the test walls, the real simulated load had the closest fractional distance to the existing damage patterns captured by photogrammetry. This method was then applied to diagnose possible causes of cracking on a foundation wall in the Baptistery of San Giovani in Florence, Italy.
关键词： Distinct element modeling,Masonry,Building pathology,Diagnosis,Crack propagation,Photogrammetry
更新于2025-09-23 15:23:52
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Multi-step approach for automated scaling of photogrammetric micro-measurements
摘要： Photogrammetry can be used for the measurement of small objects with micro-features, with good results, low costs, and the possible addition of texture information to the 3D models. The performance of this technique is strongly affected by the scaling method, since it retrieves a model that must be scaled after its elaboration. In this paper, a fully automated multi-step scaling system is presented, which is based on machine vision algorithms for retrieving blurred areas. This method allows researchers to find the correct scale factor for a photogrammetric micro model and is experimentally compared to the existing manual method basing on the German guideline VDI/VDE 2634, Part 3. The experimental tests are performed on millimeter-sized certified workpieces, finding micrometric errors, when referred to reference measurements. As a consequence, the method is candidate to be used for measurements of micro-features. The proposed tool improves the performance of the manual method by eliminating operator-dependent procedures. The software tool is available online as supplementary material and represents a powerful tool to face scaling issues of micro-photogrammetric activities.
关键词： Depth from focus,Photogrammetry,Micro-features,Measurement,International standards,Image analysis,Scale
更新于2025-09-23 15:23:52
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Forensic 3D documentation of skin injuries using photogrammetry: photographs vs video and manual vs automatic measurements
摘要： Accurate and precise documentation of lesions is an important aspect of the forensic pathologists’ work. Photogrammetry provides a useful tool to take precise measurements from photographs. These photographs are normally acquired with single camera photographs, but the procedure is quite time-consuming. Video recording has the potential to record a larger amount of image data faster. We documented 33 cadaveric skin lesions, using photographs and video recordings. The dimensions of the lesions ranged between 0.27 and 21.8 cm. The measurements of the lesions were extracted with both manual and automatic point measurements from photographs and from video frames, respectively. Very small differences (mean and median < 1 mm) were found between measurements taken in photographs versus video frames. Video frames were often blurred, preventing clear demarcation of the edges of the lesions and presenting a larger amount of noise in the 3D models. The differences between the manual point and automatic point measurements were very small (mean and median < 1 mm), but the manual procedure is to be preferred, since automatic points were not always located on the edges of the lesions. The only aspect in which video frames were superior to photographs was the recording time: video recording was almost five times faster than the photo sessions. In conclusion, this study shows that precise and comparable measurements can be extracted both from photographs and video frames. The video is the fastest method, but the use of photographs is still recommended. Manual measurements are more precise than automatic measurements and equally time-consuming.
关键词： Skin injuries,Video documentation,Photogrammetry,3D documentation
更新于2025-09-23 15:23:52
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Optical coordinate measurements in automotive industry
摘要： Photogrammetry is a technique of measuring 3D coordinates using photography as the main medium of metrology. This paper describes the use of the photogrammetric system in the automotive industry for control and measuring tasks. This contactless method is suitable for industrial application, because the measuring instruments are robust and mobile, so precise measurements are possible in production conditions. Presented results of measurements show that the optical measuring systems are powerful tools for quality control, analysis and discovering of causes of faults.
关键词： photogrammetry,optical measurement,accuracy,automotive industry
更新于2025-09-23 15:23:52
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Very High-Resolution Imaging of the City of Goma (North Kivu, D.R. Congo) Using SFM-MVS Photogrammetry
摘要： In complex tropical environment, where the dense vegetation and weather conditions limit the classical use of satellite remote sensing techniques, airborne remote sensing remains the best solution to image large areas in very high spatial resolution. However, implementing such a survey in complex areas like in the region of Goma, North Kivu, Democratic Republic of Congo (DRC), is difficult, expensive and not suitable for fast imaging during crisis periods (the city of Goma is indeed threatened by volcanic eruptions and frequently affected by armed conflicts). Thanks to the support of the Mission of the United Nations in the DRC, we tested the application of Structure-from-Motion Multi-View Stereo photogrammetry to image Goma and its vicinity (~140 km2) using a helicopter and consumer-grade DSLR cameras. The resulting orthomosaic has a spatial resolution of 17.5cm and provides unprecedented details of the city. Direct applications are detailed urban, cadastral and natural hazards mapping.
关键词： Urban Mapping,Volcanic Hazards,Photogrammetry,Central Africa,North Kivu
更新于2025-09-23 15:22:29
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Improvement of photogrammetric accuracy by modeling and correcting the thermal effect on camera calibration
摘要： This paper presents a new method for improving the geometric accuracy of photogrammetric reconstruction by modeling and correcting the thermal effect on camera image sensor. The objective is to verify that when the temperature of image sensor varies during the acquisition, image deformation induced by the temperature change is quantifiable, modelisable and correctable. A temperature sensor integrated in the camera enables the measurement of image sensor temperature at exposure. It is therefore natural and appropriate to take this effect into account and to finally model and correct it after a calibration step. Nowadays, in cartography applications performed with UAV, the frame rate of acquisitions is continuously increasing. A high frame rate over a long acquisition time can result in an important temperature increase of the image sensor and thus introduces image deformations. The correction of the above-mentioned effect can improve the measurement accuracy. We present three methods to calibrate the thermal effect and experiments on two datasets are carried out to verify the improvement in terms of the photogrammetric accuracy.
关键词： Metrology,Photogrammetry,CMOS,Thermal deformation
更新于2025-09-23 15:22:29
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The Placement of Digitized Objects in a Point Cloud as a Photogrammetric Technique
摘要： The frequency of video-capturing collision events from surveillance systems are increasing in reconstruction analyses. The video that has been provided to the investigator may not always include a clear perspective of the relevant area of interest. For example, surveillance video of an incident may have captured a pre- or post-incident perspective that, while failing to capture the precise moment when the pedestrian was struck by a vehicle, still contains valuable information that can be used to assist in reconstructing the incident. When surveillance video is received, a quick and efficient technique to place the subject object or objects into a three-dimensional environment with a known rate of error would add value to the investigation. In addition, once the objects have been placed into the three-dimensional environment, the investigator would then be able to observe the physical evidence and environment from any perspective, including viewing and measuring what cannot be seen in the video perspective. In this research, the proposed photogrammetric technique of visually placing objects within three-dimensional laser scans will be evaluated. This research aims to quantify the rate of error of taking measurements of these objects to known fixed reference points both in and out of view of the camera, and provide an efficient technique that can be employed by reconstructionists using only one software package. As a result of this research, the authors have developed an expedient, less time-intensive photogrammetric technique for the placement of three-dimensionally scanned objects and environments. This technique can take less than half of the time of a conventional photogrammetric solution.
关键词： Photogrammetry,Video footage,3D scanning,Surveillance video,Laser scanning,Scanagrammetry,Accident reconstruction,Drivecam,Dashcam
更新于2025-09-23 15:22:29
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A Portable Mirror Stand for Clinical Facial Photo Documentation
摘要： In plastic surgery, patient photography is a vital component of clinical, educational, legal, and research documentation. Optimal acquisition of photographic data requires a dedicated photography studio or a three-dimensional anatomic scanner, both of which are financially impractical for most clinicians. Simplified photo standardization is proposed for use in random clinical settings by using a portable device called the Mirror Stand (MirS). This model device aims to mimic a studio environment by incorporating the basic elements of producing consistent photographs. The pilot MirS is designed for facial photography. Images of 40 random subjects were obtained using the MirS with three different cameras. Real anthropometric measurements of each subject were collected, compared with the photographic measurements, and analyzed. In this study, all three cameras produced equally reliable measurements. Actual facial measurements were comparable to the photogrammetric measurements obtained from photographs taken using the MirS. A constant formula was derived; it allowed the conversion of photographic values into real anthropometric values. The MirS produced consistent photographs with respect to the measurements. The photographs obtained could be translated reliably into their real anthropometric measurements. Therefore, the MirS can be applied in daily practice, providing an efficient alternative for obtaining a standard justifiable photograph.
关键词： Photogrammetry,Cephalometry,Surgery, plastic,Anthropometry
更新于2025-09-23 15:22:29
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UTILIZA??O DE ALVOS CODIFICADOS DO TIPO ARUCO NA AUTOMA??O DO PROCESSO DE CALIBRA??O DE C?MARAS
摘要： This paper presents a proposal for the automation of the camera calibration process, locating and measuring image points in coded targets with sub-pixel precision. This automatic technique helps minimize localization errors, regardless of camera orientation and image scale. To develop this technique, several types of coded targets were analyzed and the ARUCO type was chosen due to its simplicity, ability to represent up to 1024 different targets and availability of source code implemented with the OpenCV library. ARUCO targets were generated and two calibration sheets were assembled to be used for the acquisition of images for camera calibration. The developed software can locate targets in the acquired images and it automatically extracts the coordinates of the four corners with sub-pixel accuracy. Experiments were conducted with real data showing that the targets are correctly identified unless excessive noise or fragmentation occurs mainly in the outer target square. The results with the calibration of a low cost camera showed that the process works and that the measurement accuracy of the corners achieves sub-pixel precision.
关键词： Calibration Chambers,Targets Coded,Photogrammetry,ARUCO,OpenCV,Sub-Pixel
更新于2025-09-23 15:22:29