Deformation Measurements of Gabion Walls Using Image Based Modeling

The image based modeling finds use in applications where it is necessary to reconstruct the 3D surface of the observed object with a high level of detail. Previous experiments show relatively high variability of the results depending on the camera type used, the processing software, or the process evaluation. The authors tested the method of SFM (Structure from Motion) to determine the stability of gabion walls. The results of photogrammetric measurements were compared to precise geodetic point measurements

Photogrammetry as efficient tool for documentation of actual realization of construction

Digital era brought to the discipline photogrammetry significant changes. In the past, only specialized and expensive equipment both on imaging and image processing could be used for metrical purposes and the operator had to have considerable expertise. It is now possible to use conventional digital cameras, image processing is implemented on the PC by software at affordable prices and the actual software is built to be "user friendly" to experts from other disciplines such as photogrammetry. Paper aims to bring the possibility of photogrammetry as a efficient measurement tool for variety of professions including forensic science.Digitálna doba priniesla aj do vednej disciplíny fotogrametrie významné zmeny. V minulosti bolo možné využívať na metrické účely len špecializované a drahé prístroje tak na snímkovanie ako aj na spracovanie snímok a spracovateľ musel disponovať nemalými odbornými vedomosťami. V súčasnosti je možné využívať bežné digitálne fotoaparáty, spracovanie snímok sa realizuje na PC softvérmi v dostupných cenách a samotné softvéry sú zostavené tak, aby boli „užívateľsky priateľské“ odborníkom aj z iných vedných disciplín ako je fotogrametria. Príspevok má za cieľ priblížiť možnosti fotogrametrie ako efektívneho meracieho nástroja pre rôzne profesie vrátane súdneho znalectva

3D DIGITAL RECONSTRUCTION BASED ON ARCHIVED TERRESTRIAL PHOTOGRAPHS FROM METRIC CAMERAS

The paper deals with the possibilities and limitations of the image processing of digitalized terrestrial photographs from analogue metric cameras. By the end of the 20th century, analogue metric cameras such as Zeiss UMK were used for documentation purposes in the fields of industrial and investment construction, nature and landscape preservation, heritage preservation, etc. Currently, the collections of photographs are stored at specialized archives of many different institutions, such as libraries, museums, universities, etc. These sets of photographs provide a material background for a 3D digital reconstruction of a subject of interest at the time of taking the photographs. The digital image processing of old photographs may be more difficult due to unknown parameters of the used camera, such as the focal length, image coordinates of the fiducial marks and distortion parameters of the lens system, etc. In this case, it may be difficult to process these photographs in a photogrammetric software. The paper presents a methodology for the digital photogrammetric processing of analogue terrestrial photographs. The data processing is based on the parameters of the used metric cameras, which are described in their calibration reports. The image processing was tested in two commercial photogrammetric software tools that utilize the technology of Structure-from-Motion (SfM) or multiimage intersection photogrammetry to process image datasets

CHANGE OF A HIGHWAY ROUTE CAUSED BY A ROCKSLIDE

During the spring of 2013, a relatively large rockslide with a total area of 96,952 m2 occurred in the eastern part of the Malá Fatra mountains. The anticipated depth of the slip surfaces was from 30 to 40 metres and the volume of moving mass was estimated to be 2,000,000 m3. The maximum movement of the rockslide on the first day in March 2013 was estimated to be 43 m. The front of the rockslide interfered with the projected D1 highway route. The paper presented here offers an analysis of the causes of the rockslide and its activity in association with the potential threat to the proposed highway

Measurement of Flat Slab Deformations by the Multi-Image Photogrammetry Method

The use of photogrammetry during load tests of building components is a common practise all over the world. It is very effective thanks to its contactless approach, 3D measurement, fast data collection, and partial or full automation of image processing; it can deliver very accurate results. Multi-image convergent photogrammetry supported by artificial coded targets is the most accurate photogrammetric method when the targets are detected in an image with a higher degree of accuracy than a 0.1 pixel. It is possible to achieve an accuracy of 0.03 mm for all the points measured on the object observed if the camera is close enough to the object, and the positions of the camera and the number of shots are precisely planned. This contribution deals with the design of a special hanging frame for a DSLR camera used during the photogrammetric measurement of the deformation of flat concrete slab. The results of the photogrammetric measurements are compared to the results from traditional contact measurement techniques during load tests

Deformation Measurements of Gabion Walls Using Image Based Modeling

The image based modeling finds use in applications where it is necessary to reconstructthe 3D surface of the observed object with a high level of detail. Previous experiments showrelatively high variability of the results depending on the camera type used, the processingsoftware, or the process evaluation. The authors tested the method of SFM (Structure fromMotion) to determine the stability of gabion walls. The results of photogrammetricmeasurements were compared to precise geodetic point measurements

Photogrammetry as efficient tool for documentation of actual realization of construction

Digital era brought to the discipline photogrammetry significant changes. In the past, only specialized and expensive equipment both on imaging and image processing could be used for metrical purposes and the operator had to have considerable expertise. It is now possible to use conventional digital cameras, image processing is implemented on the PC by software at affordable prices and the actual software is built to be "user friendly" to experts from other disciplines such as photogrammetry. Paper aims to bring the possibility of photogrammetry as a efficient measurement tool for variety of professions including forensic science

Deformations of Image Blocks in Photogrammetric Documentation of Cultural Heritage—Case Study: Saint James’s Chapel in Bratislava, Slovakia

Structure from motion photogrammetry is currently one of the most frequently used technologies for the documentation of archaeological sites. Due to the relatively high freedom in choosing the position and orientation of the cameras, qualitatively different results for the reconstructed geometry can be achieved. Therefore, in the presented study, we focused on monitoring the changes in the geometry of point clouds obtained with different configurations of the camera network during the digitization of Saint James’s Chapel in Bratislava city. The changes of the tested photogrammetric variants were analyzed through comparison with scans from terrestrial laser scanning. The results suggest that caution should taken when striving for image recording efficiency, as insufficient connections between image blocks can lead to a decrease in relative accuracy, down to a level worse than 1:1000