A review and analyses of plumb‐line calibration

Recently, pixel numbers and functions of consumer grade digital camera are amazingly increasing by modern semiconductor and digital technology, and there are many low-priced consumer grade digital cameras which have more than 10 mega pixels on the market in Japan. In these circumstances, digital photogrammetry using consumer grade cameras is enormously expected in various application fields. There is a large body of literature on calibration of consumer grade digital cameras and circular target location. Target location with subpixel accuracy had been investigated as a star tracker issue, and many target location algorithms have been carried out. It is widely accepted that the least squares models with ellipse fitting is the most accurate algorithm. However, there are still problems for efficient digital close range photogrammetry. These problems are reconfirmation of the target location algorithms with subpixel accuracy for consumer grade digital cameras, relationship between number of edge points along target boundary and accuracy, and an indicator for estimating the accuracy of normal digital close range photogrammetry using consumer grade cameras. With this motive, an empirical testing of several algorithms for target location with subpixel accuracy and an indicator for estimating the accuracy are investigated in this paper using real data which were acquired indoors using 7 consumer grade digital cameras which have 7.2 mega pixels to 14.7 mega pixels.

Motivated by the formation of fingerprint patterns, we consider a class of interacting particle models with anisotropic, repulsive-attractive interaction forces whose orientations depend on an underlying tensor field. This class of models can be regarded as a generalization of a gradient flow of a nonlocal interaction potential which has a local repulsion and a long-range attraction structure. In addition, the underlying tensor field introduces an anisotropy leading to complex patterns which do not occur in isotropic models. Central to this pattern formation are straight line patterns. For a given spatially homogeneous tensor field, we show that there exists a preferred direction of straight lines, i.e., straight vertical lines can be stable for sufficiently many particles, while many other rotations of the straight lines are unstable steady states, both for a sufficiently large number of particles and in the continuum limit. For straight vertical lines we consider specific force coefficients for the stability analysis of steady states, show that stability can be achieved for exponentially decaying force coefficients for a sufficiently large number of particles, and relate these results to the Kücken--Champod model for simulating fingerprint patterns. The mathematical analysis of the steady states is completed with numerical results.

Although zoom lens has been widely accepted in vision system, the use of zoom lens was not general in close range photogrammetry from the view point of instability by zooming. However, with the spread of consumer grade digital cameras with integrated zoom lens, in particular long range such as ×35, digital close range photogrammetry using the camera is enormously expected in various application fields. There is a large body of literature on calibration of zoom lens. However, there is still problem for effective digital photogrammetry using the camera. The problem is practical calibration model for zoom lens, in particular correction of misalignment which is caused by zoom setting. In order to resolve instability of zoom lens, and practical use of digital close range photogrammetry using zoom lens, a new calibration model is proposed in this paper based on correction of zoom lens misalignment. Furthermore, in order to evaluate the proposed calibration model for zoom lens, calibration tests were conducted using 5 kinds of consumer grade digital camera with integrated zoom lens (×3~5), 3 kinds of long range consumer grade digital camera (×12~30) and digital SLR camera with zoom lens (×11).

Synthetic and analytical methods are usually used to investigate multidimensional spaces and sets of subspaces. Shortcomings of a synthetic method — the appeal to spatial imagination and the researcher´s intuition, impossibility of formalization, need of creation of big and complex logical constructions don´t allow to go beyond four-dimensional space, with rare exceptions. The theory of enumerative geometry submitted as geometry of conditions with a basic element – a multidimensional flags incidence condition allows solve many problems which up to now were considered as insoluble ones. The simplest of such problems is a classical problem for calculation of final number of given space’s subspaces meeting the set of given conditions (the normal problem of algebraic geometry). A more serious problem – calculation a number and values of algebraic characteristics for given variety in given space. For this problem solution it was necessary to develop a formalized method, as well as technique algorithmization. This problem has been solved by professor. V.Ya. Volkov in his doctoral dissertation by means of developed by him so-called e-calculations. For an understanding of e-calculation fundamentals or calculation of Schubert conditions a rather good mathematical background and method promotion are necessary. The last demands consideration of various approaches to conditions calculation problem. In the present paper are considered the simplest cases of a tabular method for conditions calculation, in relation to conditions of incidence which is understood in a general sense. Calculation of one-, two- and ((k + 1) (n – k) – 1)-dimensional conditions are considered. Conditions calculation formalization and incidence conditions reduction are explained. The problem about a final number of straight lines crossing the set number of k-planes in n-dimensional space is considered as an example. In particular, the problem about a number of straight lines crossing some number of the set straight lines can be correct only in three- and four-dimensional spaces. Conditions of the minimum multiplicity equal to three exist only in (3k + 1)-dimensional spaces. Conditions of the multiplicity equal to four exist only in odd dimensionality spaces. And so on. The concrete number of straight lines in all cases can be counted by reduction of the corresponding conditions.

Recently, the documentation and visualization of various cultural heritages have been receiving attention, and a small Buddha such as less than 10 cm tall which was stored in the womb of Buddha is also included in cultural heritages. Zoom lenses are generally used to document these small objects and thus conserve the cultural heritage. However, there exist certain issues pertaining to the use of zoom lenses for such digital documentation. These issues include image sharpness and distortions that occur with changes in focal length setting, and in particular, the depth of field is issue from application standpoint such as documentation of the small cultural heritage. On the other hand, macro lenses can be used to capture sharp images of small objects from the view point of working distance, and its depth of field is related to the aperture of the camera. In order to evaluate the effectiveness of macro lenses in digital close range photogrammetry, macro lens and zoom lens were mounted on a digital single lens reflex camera (Canon EOS20D, 8.2 Mega pixels). This paper deals in a first part with comparative evaluations for both lenses with respect to their lens distortion, imaging mode, and calibration aspects. The results indicated that macro lenses were more suitable for digital close range photogrammetry. Calibration tests are performed to demonstrate the effectiveness and practicability of macro lens in close range photogrammetic applications.

Various surveying techniques has been used in the mapping for engineering purposes. Mapping is an important element in Geomatic Engineering. Conventional technique for mapping includes surveying technique that consist of data acquisition work on site, plotting and calculating. This technique is tedious and time consuming. This study is aimed at studying and a comparing an alternative technique for mapping of the Kellies Castle building, namely digital close-range photogrammetry. The purpose of introducing close range photogrammetry technique in mapping is to increase efficiencies of estimation process as well the reliability of the results. Photogrammetry procedures were sets up to determine the map. Then, a simple verification test is done to verity the result using digital close-range photogrammetry. Comparison between digital close-range photogrammetry and conventional technique was made to prove that digital close-range photogrammetry capable to be used as one of the reliable techniques in non-topo mapping.

This study presents a comprehensive comparative analysis of Terrestrial Laser Scanning (TLS) and Digital Close-Range Photogrammetry (DCRP) against traditional Total Station (TS) methods for 3D spatial documentation across a range from 8.00 meters to 2.00 mm. The analysis was conducted through three scenarios: Ground Control Points (GCPs), the Kafrelsheikh University Mosque, and Kafr El Sheikh Tanta Road. Paired t-tests and ANOVA revealed statistically significant differences (p < 0.05) across all variables, with TLS demonstrating superior precision. TLS deviations in linear distance measurements were as low as 2 mm compared to TS, while DCRP exhibited variations ranging from 0.02 m to 0.30 m depending on surface reflectivity and distance. Pearson correlation coefficients exceeded 0.95 for TLS across all axes (X, Y, Z), highlighting its reliability. DCRP, while slightly less consistent, showed minor variability, particularly in the Z-axis. For road crack measurements, TLS captured lengths ranging from 180 mm to 750 mm (mean = 501.417 mm, SD = 207.341 mm), which aligned closely with DCRP results (mean = 504.867 mm, SD = 204.455 mm). The mosque’s complex geometry showcased TLS's higher precision (ANOVA F = 15.78, p = 0.0001 for the Y-axis), while DCRP provided faster data acquisition and reduced costs. Both methods demonstrated significant statistical alignment, though TLS consistently outperformed DCRP in accuracy, especially for intricate structures requiring high precision. The findings emphasize the complementary strengths of TLS and DCRP, recommending their integration to achieve an optimal balance of accuracy, efficiency, and cost-effectiveness. Future research should focus on improving the precision of DCRP for detailed architectural and structural documentation while exploring hybrid techniques to enhance the reliability and scalability of 3D surveying methods. Doi: 10.28991/CEJ-2025-011-03-021 Full Text: PDF

Documentation of historical caravansaries by digital close range photogrammetry

Absorber design for a Scheffler-Type Solar Concentrator

A scheme is proposed for generating multiphase oscillatory signals in millimeter-wave frequencies based on the dynamics of a traveling pulse developed in a closed transmission line periodically loaded with resonant-tunneling diodes (RTDs) that is coupled with several straight RTD lines. When supplied with an appropriate voltage at the end of an RTD line, a pulse edge is shown to exhibit a spatially extended limit-cycle oscillation on the line. We consider the case where several RTD lines are connected halfway to a closed one at even intervals. In this case, the oscillatory edge developed in each straight RTD line is mutually synchronized such that a pulse-shaped rotary traveling wave develops on the closed RTD line. The oscillating edge on each straight line is also synchronized with the traveling pulse on the closed line, such that the leading edge of the traveling pulse on the closed line and the forward edge on the straight line pass the cross point simultaneously. As a result, when N L straight lines are connected to the closed line, the phase difference between two adjacent oscillatory edges becomes 2π/N L . On the other hand, the trailing edge of the traveling pulse at the cross point breaks the voltage wave on the straight line into two pieces, one of which travels forward to form a solitary wave and the other of which travels backward to reach the input end, where it is reflected and starts to travel forward and this forward moving edge is supposed to be synchronized with the leading edge of the traveling pulse. It means that a back-and-forth edge and a forward-moving solitary wave develop periodically on each straight line. Because the time required for the traveling pulse to go around the closed line must be coincident with the period of the edge oscillation on each straight line, a unique traveling pulse cannot synchronize with each oscillating edge when the cell size of the closed line becomes large, resulting in the development of multiple traveling pulses on the closed line. In this paper, the design criteria are discussed concerning the connecting point between the straight and closed lines, the number of straight lines, and the size of the closed line. In addition, we describe several measurement results that validate the essential properties of the traveling pulse and then show several results of full-wave analysis of a monolithically integrated RTD line.

Importance of digital close-range photogrammetry in documentation of cultural heritage

Industrial metrology is one of the fastest growing areas in advanced technologies, such as electronics and optics, computation speed, and it has been increased in recent years. There are several tools used in industrial metrology, such as total stations, digital photogrammetry, and laser scanning. Close range digital photogrammetry has been implemented for an industrial piping system in terms of installation, inspection, and replacement. Laser scanning is also used for industrial measurements to generate 3D coordinates points. In order to develop a 3D modelling strategy, this thesis focuses on the development, selection and design of photogrammetric procedures and project specific targets. This thesis also explores image-acquiring sensors such as digital cameras and laser scanners in terms of their capabilities and advantages. Based on experimental setup accuracy, measurements of piping systems are compared for applications of two different sensors. Effects of different surface materials are examined in laser scanning applications and several different types of materials are used for acquiring point clouds data. Measurement of pipes' diameters and residual analyses are conducted with different surface materials, which are used for industrial pipes. Significant improvement in laser scanning data acquisition is examined in terms of data quality both quantitatively and qualitatively during the residual analyses.

Industrial metrology is one of the fastest growing areas in advanced technologies, such as electronics and optics, computation speed, and it has been increased in recent years. There are several tools used in industrial metrology, such as total stations, digital photogrammetry, and laser scanning. Close range digital photogrammetry has been implemented for an industrial piping system in terms of installation, inspection, and replacement. Laser scanning is also used for industrial measurements to generate 3D coordinates points. In order to develop a 3D modelling strategy, this thesis focuses on the development, selection and design of photogrammetric procedures and project specific targets. This thesis also explores image-acquiring sensors such as digital cameras and laser scanners in terms of their capabilities and advantages. Based on experimental setup accuracy, measurements of piping systems are compared for applications of two different sensors. Effects of different surface materials are examined in laser scanning applications and several different types of materials are used for acquiring point clouds data. Measurement of pipes' diameters and residual analyses are conducted with different surface materials, which are used for industrial pipes. Significant improvement in laser scanning data acquisition is examined in terms of data quality both quantitatively and qualitatively during the residual analyses.

The digital close range photogrammetry (DCRP) approach has been used for tree's age estimation from its photographs with image analysis. Age of a tree can be determined using diameter or from the circumference, then convert it into diameter of a tree. The aim of this study is to determine the age of a tree by measuring tree diameter using close range photogrammetry technique. Conventional method was used to estimate the age of a tree by determining diameter at breast height (DBH) by using a measuring tape. Three jelutong trees with a different size were used in this study. Finding of the results shows the 3D representation of three sample trees with their circumference and diameter measurement compared to the conventional reading. From the analysis it was found that the different between conventional and DCRP method on tree age estimation on tree id 020, 047 and 053 yields 0.313%, 0.850% and 0.424% respectively.

Nanotextured Surfaces with Underwater Anisotropic Sliding Resistance for Oil Transfer and Coalescence