Photogrammetry for Cooling Tower Shape Surveys

Chisholm, Nichole

doi:10.1111/j.1477-9730.1977.tb00080.x

Cited by 5 publications

(4 citation statements)

References 2 publications

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“…Another approach involves employing thermography to identify alterations in concrete materials, such as structural damage [19]. An alternative for detecting damage by laser scanning is photogrammetry [20][21]. UAVs increase data availability from the above.…”

Section: Introductionmentioning

confidence: 99%

Damage detection on cooling tower shell based on model textures

Zahradník,

Roučka

2024

CEJ

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Ensuring the structural integrity of cooling towers is paramount for safety and efficient operation. This paper presents a novel approach for detecting damage on cooling tower shells, utilising textures derived from laser scanning and close-range photogrammetry. The proposed method delves beyond the limitations of solely relying on colour information by harnessing the rich details embedded in various textures, including diffuse, normal, displacement, and occlusion. The study demonstrates the efficacy of this approach for identifying significant concrete damage. A Convolutional Neural Network (CNN) trained on diffuse textures successfully detects high damage instances with minimal misdetection. However, accurately pinpointing low damage, often manifesting as subtle cracks, and mimicking other patterns like air pores, ribbing, and colour variations, presents a formidable challenge. To tackle this challenge, the authors introduce a novel "composed raster layer" that merges information from multiple textures. This pre-processed layer amplifies the visual cues associated with low damage, facilitating its differentiation from similar patterns. While the current implementation employing multi-resolution segmentation and rule-based classification exhibits promising results, further optimization is acknowledged to refine the accuracy of low damage detection. The successful application of textures commonly used in rendering techniques underscores their remarkable potential for enhancing damage detection in civil engineering applications. While acknowledging limitations such as the analysis of a single cooling tower and the reliance on specific software for damage detection, the study proposes future research directions. This research holds significant implications for the field of civil engineering by offering a promising approach for automated and efficient damage detection on cooling tower shells.

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Section: Introductionmentioning

confidence: 99%

Damage detection on cooling tower shell based on model textures

Zahradník,

Roučka

2024

CEJ

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“…Only in the last 10-15 years have we seen significant developments in sensor equipment to provide researchers with vast quantities of 3D spatial data. Use of ground-based Global Position Systems (GPS) topographic information and aerial photography represent the early phases of recent developments in the field, where DEMs were created using photogrammetry and validated by ground GPS surveys (Chisholm, 1977;Chandler et al, 1989;Chandler, 1999;Lane, 2000;Brasington et al, 2003). Hilker et al, 2010;Rodríguez-Caballero et al, 2016) and is one of the main influences on accuracy achieved (Hancock, 2006;Bater and Coops, 2009).…”

Section: Introductionmentioning

confidence: 99%

3D mapping efficacy of a drone and terrestrial laser scanner over a temperate beach-dune zone

2019

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Understanding dynamic earth surface processes requires various spatial and temporal information to help produce patterns of landform change. Recent developments in sensor technology such as Structure from Motion (SfM), camera-mounted airborne Unmanned Aerial Vehicles (UAVs) and Terrestrial Laser Scanning (TLS) have provided a means of acquiring high-resolution spatial data on land surface topography. Through repeat surveys, these techniques enable much better understanding of what is termed 'geomorphometry', where we can examine a geomorphic surface for change over space and time. In coastal environments, change can involve significant alteration and generation of landforms over relatively short periods and, therefore, we require a means of measuring surface morphology quickly and over large areas. Here, we examine a section of a beach-dune system in NW Ireland using SfM-UAV and TLS plus baseline dGPS data points to assess the value of these techniques and to understand their effectiveness (and limitations). Issues such as accuracy, resolution and differences of Digital Elevation Models (DEMs) are assessed for their efficiency, associated challenges and relative performance over variations in terrain types and analytical approaches. We also examine the implications for differences in areal and volume calculations of the coastal landforms using the both approaches. We find that sensor performance is highly dependent on the terrain being measured, with undulations, slope, vegetation cover, acquisition resolution (point density) and interpolation issues all having pronounced impacts on effectiveness and data quality. In general, the TLS performed better over flatter, low-angled topography containing sparse/non-vegetated areas than in areas

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“…The selection of a measurement method is as important as the grid density. For the measurement of shell structures, the most commonly used methods include the photogrammetric method (Chisholm, 1977), the method of ambient tangents (Jasińska and Preweda, 2004), spatial intersection (Ding et al, 1996;Shortis and Fraser, 1991), or the polar 3D method, prevalent in the era of total stations with a possibility of re ectorless measurements (Woźniak and Woźniak, 2011;Woźniak, 2008). Currently, a large development of laser scanning technology is observable, and it is useful in many areas.…”

Section: Introductionmentioning

confidence: 99%

Measurement point density and measurement methods in determining the geometric imperfections of shell surfaces

Kocierz

Rębisz

Ortyl

2018

Reports on Geodesy and Geoinformatics

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In geodetic measurements of deformations in shell cooling towers, an important factor is to optimize the number of points representing the exterior surface of the shell. The conducted analyses of damage to such structures proved that cooling towers exhibited shell deformation consisting of irregular vertical waves (three concavities and two convexities), as well as seven horizontal waves. On this basis, it is claimed that, in accordance with the Shannon theorem, the correct representation of the generated waves requires the measurement of the cooling tower shell in a minimum of 12 vertical and 14 horizontal sections. Such density of the points may not be sufficient to represent local imperfections of the shell. The article presents the results of test measurements and their analysis, which were conducted to verify the assumptions as to the optimal number of measurement points for the shell of a cooling tower. The evaluation was based on a comparative analysis of the data obtained by the Terrestrial Laser Scanning (TLS) method, creating a very detailed model of geometric imperfections in an actual cooling tower with a height of 100 m. Based on the data obtained by the TLS method, point grids of various density were generated. An additional measurement of the cooling tower shell deformation was performed using a precise electronic total station with reflectorless measurement option. Therefore, it was possible to assess the accuracy of measurements by laser scanning in relation to measurements obtained by reflectorless total stations.

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Photogrammetry for Cooling Tower Shape Surveys

Cited by 5 publications

References 2 publications

Damage detection on cooling tower shell based on model textures

Damage detection on cooling tower shell based on model textures

3D mapping efficacy of a drone and terrestrial laser scanner over a temperate beach-dune zone

Measurement point density and measurement methods in determining the geometric imperfections of shell surfaces

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