LANDSLIDE MONITORING USING CLOSE RANGE PHOTOGRAMMETRY

This paper presents the preliminary results of a simulation study on the production of low cost Digital Elevation Model (DEM) for a landslide study area in Seri Iskandar, Perak. The important objective of this paper is to present the potentiality of Close Range Photogrammetry (CRP) as a data acquisition tool in producing a Digital Elevation Model (DEM) by using data from surface measurement. This method was applied using stereopair photographs captured data from ground level detection, or known as close range photogrammetry with the use of a digital camera mounted on a tripod as a tool for data collection. Close Range Photogrammetry (CRP) applications is useful for mapping of areas that are difficult and risky to point manpower on terrain that consist of steep and dangerous slopes. Conventional methods require measurement using Electronic Distance Measuring (EDM), but this method is very costly and requires a survey team placed on the land site area. The research data were carried out with two different epoch data. The outcome proves that CRP can produce DEM with less cost compared to other methods.

Analisis Perbandingan Ketelitian Model 3D Menggunakan Lensa Normal dan Lensa Fisheye

Dalam pemodelan 3D, salah satu metode yang umum digunakan adalah close range photogrammetry (CRP). Pada umumnya, metode CRP menggunakan lensa normal akibat distorsinya yang tidak terlalu besar. Lensa fisheye memiliki sudut pandang yang lebih besar dibandingkan lensa normal sehingga dapat mengurangi jumlah foto namun memiliki distorsi yang besar sehingga dapat mempengaruhi ketelitian model 3D yang dihasilkan. Penelitian ini bertujuan untuk melakukan pengujian ketelitian geometrik antara lensa normal dan lensa fisheye. Penelitian dilakukan di Kawasan Candi Ratu Boko. Data yang digunakan adalah foto objek candi, 10 titik GCP dan 10 titik ICP. Hasil model 3D lensa normal dan lensa fisheye sudah dapat memvisualisasikan objek dengan baik dari tingkat kedetilan dari struktur yang dihasilkan. Uji geometrik dilakukan dengan membandingkan jarak pada kedua model dengan jarak di lapangan serta ukuran ICP pada kedua model dengan ukuran ICP hasil akuisisi mengunakan total station reflectorless. Kedua uji tersebut menggunakan uji -t dengan tingkat kepercayaan 95%. Uji ketelitian jarak dan koordinat ICP menghasilkan t hitung < tabel sehingga dapat disimpulkan bahwa ketelitian model 3D lensa fisheye sama dengan ketelitian model 3D lensa normal. Lensa fisheye dapat menggantikan lensa normal untuk pemodelan 3D dalam kondisi lingkungan yang sempit dan terbatas. Distorsi lensa yang besar pada lensa fisheye tidak mempengaruhi ketelitian objek secara signifikan apabila dilakukan proses kalibrasi kamera.

In a Split Second

<p>Children and adolescents with the medical condition Spastic Cerebral Palsy (CP) may develop an abnormal gait, resulting in walking difficulties. This may be helped overtime with noninvasive Ankle Foot Orthotics (AFOs) braces, such as Solid Ankle Foot Orthotics (SAFOs), customised to suit patients needs. However, the acquisition of patient measurements for customisation and manufacturing itself is manual, slow, intrusive, subjective, and requires specialist skills to accomplish. This can commonly result in negative experiences for patients and reduce the access to healthcare to many people. This can especially affect vulnerable patients such as children or adolescents with Spastic CP. Research has identified that a 3D digital system that scans patients’ limbs and prints orthotics has the potential to improve the AFO creation process through speed, accuracy, and data availability. However, this system requires new technologies to fulfill its required performance, including a reliable way to acquire the three-dimensional shape of the limbs. As such, a close-range photogrammetry system was identified as a fast and accurate alternative for producing surface measurements through 3D models compiled from images taken simultaneously. This research portfolio explores the design development of such a system by identifying areas of improvement, barriers, and solutions in a multi-method iterative research-through-design approach and pragmatic design framework. The aim was to achieve quick and accurate acquisition of a patient’s’ lower half measurements, while focusing on the experience of users during system interaction. The final output is a formally evaluated close-range photogrammetry scanner prototype, that created a non-intrusive and accurate alternative to traditional methods via quick and detailed capturing of patient surface measurements for later analysis. While also facilitating the needs of two user groups: vulnerable patients, and operating technician, to better their user experience.</p>

In a Split Second

<p>Children and adolescents with the medical condition Spastic Cerebral Palsy (CP) may develop an abnormal gait, resulting in walking difficulties. This may be helped overtime with noninvasive Ankle Foot Orthotics (AFOs) braces, such as Solid Ankle Foot Orthotics (SAFOs), customised to suit patients needs. However, the acquisition of patient measurements for customisation and manufacturing itself is manual, slow, intrusive, subjective, and requires specialist skills to accomplish. This can commonly result in negative experiences for patients and reduce the access to healthcare to many people. This can especially affect vulnerable patients such as children or adolescents with Spastic CP. Research has identified that a 3D digital system that scans patients’ limbs and prints orthotics has the potential to improve the AFO creation process through speed, accuracy, and data availability. However, this system requires new technologies to fulfill its required performance, including a reliable way to acquire the three-dimensional shape of the limbs. As such, a close-range photogrammetry system was identified as a fast and accurate alternative for producing surface measurements through 3D models compiled from images taken simultaneously. This research portfolio explores the design development of such a system by identifying areas of improvement, barriers, and solutions in a multi-method iterative research-through-design approach and pragmatic design framework. The aim was to achieve quick and accurate acquisition of a patient’s’ lower half measurements, while focusing on the experience of users during system interaction. The final output is a formally evaluated close-range photogrammetry scanner prototype, that created a non-intrusive and accurate alternative to traditional methods via quick and detailed capturing of patient surface measurements for later analysis. While also facilitating the needs of two user groups: vulnerable patients, and operating technician, to better their user experience.</p>

Underexposed Vision-Based Sensors’ Image Enhancement for Feature Identification in Close-Range Photogrammetry and Structural Health Monitoring

This paper describes an alternative structural health monitoring (SHM) framework for low-light settings or dark environments using underexposed images from vision-based sensors based on the practical implementation of image enhancement algorithms. The proposed framework was validated by two experimental works monitored by two vision systems under ambient lights without assistance from additional lightings. The first experiment monitored six artificial templates attached to a sliding bar that was displaced by a standard one-inch steel block. The effect of image enhancement in the feature identification and bundle adjustment integrated into the close-range photogrammetry were evaluated. The second validation was from a seismic shake table test of a full-scale three-story building tested at E-Defense in Japan. Overall, this study demonstrated the efficiency and robustness of the proposed image enhancement framework in (i) modifying the original image characteristics so the feature identification algorithm is capable of accurately detecting, locating and registering the existing features on the object; (ii) integrating the identified features into the automatic bundle adjustment in the close-range photogrammetry process; and (iii) assessing the measurement of identified features in static and dynamic SHM, and in structural system identification, with high accuracy.

New Measurement Methods for Structure Deformation and Objects Exact Dimension Determination

The current rapid development of technologies enables new procedures for deformation and the detecting of construction defects and their modelling and monitoring in BIM. New instruments were developed for fast and sufficiently accurate mapping like personal mobile laser scanners (PLS). In the world of photography, the size of camera sensors is bigger, and the photographs are sharper. The rapid development of computer performance enables automatic and complex calculations, which lead to large sets of detailed 3D data and a high degree of automation. This influences photogrammetry and its methods. The results are more detailed and more accurate. Deformation, defects and exact dimensions (metrology) of different structures or objects can be currently measured by digital close-range photogrammetry. Cracks and cavities are monitored for structure status detection. This is important for planning reconstruction and for financial reasons. For structures like cooling towers, chimneys, or bridges can be created on a 3D model with a high texture resolution for finding and monitoring cracks and cavities. Deformations or defects that were found must be in scale, and measurable for the calculation of the scope of repair work and its price. The generated 3D object model can then be used for further measurements, for the price estimation of renovation, and for the creation of a BIM, in which all processes can be modelled and watched. Deformation can be monitored over time by creating additional models after a defined period. Captured 3D models from different periods can be compared in software like CloudCompare to determine the progress of degradational changes. The trend of the aging of the structure can be traced, which will be helpful for the reasonable planning of reconstruction. Based on the rapid development and miniaturization of measuring devices, new, smaller, easier to use, and more perfect devices are constructed. This also applies to the new group of laser scanners constructed for basic measurement and structure modeling for BIM. Conventional laser scanners can be accurate, but they are relatively large and heavy, difficult to transport and measuring with them is relatively slow (stop and go type). If the project goal is the classic construction, documentation of the object, data transfer to BIM or basic documentation of objects, PLS is the ideal device. Thanks to the development of accurate IMU (inertial measurement unit) and SLAM (simultaneous localization and mapping) technologies, these devices are on the rise. The forthcoming article will inform about the methods of accurate close-range photogrammetry and mobile laser scanning and will show their advantages with specific examples.