Digital Rectification Research Articles

An alternating continuous integration system for magnetic measurements for experimental advanced superconducting tokamak.

Integrators are critical instruments used for magnetic measurement systems (MMSs) in tokamaks, and, currently, the Experimental Advanced Superconducting Tokamak (EAST) has over 600 deployed. However, these integrators, designed with real-time drift compensation, will not be able to support longer pulse operations in the near future due to saturation and drift. To address these issues, this paper proposes a new alternating integration system combining analog integration with drift digital rectification. This system utilizes a microcontroller unit (MCU) to control two parallel analog integrators to work alternatively, compensate their drifts based on their respective error characteristics, and assemble the two integration segments together. The designed architecture provides highly flexible capabilities in operation modes and error correction, which make the system operation and maintenance highly automated. Performance tests on the EAST experiment site show that the prototype integrator can meet the requirements of real-time plasma control for a duration of hour-level.

Characterising the Mould Rectification Process for Designing Scoliosis Braces: Towards Automated Digital Design of 3D-Printed Braces

The plaster-casting method to create a scoliosis brace consists of mould generation and rectification to obtain the desired orthosis geometry. Alternative methods entail the use of 3D scanning and CAD/CAM. However, both manual and digital design entirely rely on the orthotist expertise. Characterisation of the rectification process is needed to ensure that digital designs are as efficient as plaster-cast designs. Three-dimensional scans of five patients, pre-, and post-rectification plaster moulds were obtained using a Structure Mark II scanner. Anatomical landmark positions, transverse section centroids, and 3D surface deviation analyses were performed to characterise the rectification process. The rectification process was characterised using two parameters. First, trends in the external contours of the rectified moulds were found, resulting in lateral tilt angles of 81 ± 3.8° and 83.3 ± 2.6° on the convex and concave side, respectively. Second, a rectification ratio at the iliac crest (0.23 ± 0.04 and 0.11 ± 0.02 on the convex and concave side, respectively) was devised, based on the pelvis width to estimate the volume to be removed. This study demonstrates that steps of the manual rectification process can be characterised. Results from this study can be fed into software to perform automatic digital rectification.

USING DIGITAL TERRESTRIAL PHOTOGRAMMETRY IN CULTURAL HERITAGE CASE STUDY: THE GREAT WALL OF GORGAN IN IRAN

Abstract. An assessment of the influence of using digital terrestrial photogrammetry for surveying and documentation of cultural objects is presented in this paper. The approaches including digital image enhancement, digital rectification and restitution, feature extraction for the creation of a three-dimension geographical information system model from the photogrammetric record and the computer visualisation of cultural monuments. Manual three-dimension processing of terrestrial images using analogue photogrammetric procedures is slow, can register little information and has limited application and cannot be re-examined if the information desired is not directly presented. In addition, it is a very time-consuming task and requires the skill of qualified personnel. It seems there is a need for an environment-based information system with the ability to display precise and measurable imagery for use of the architectural and archaeological information system by integrating digital photogrammetry and AutoCAD facilities as applicable to support the reconstruction of many cultural heritage places. Architectural structuring and guidelines can be used to develop invaluable historical monuments in Iran such as the Great Wall of Gorgan. While the research is in completion, the output of the Great Wall of Gorgan can be documented and recorded in the world.

Reliable and Practical City Map generation at 1:1000 or 1:500 scale based on “Five control points" recification of digitized images

Abstract. Using high resolution image for making city map by digital rectification is simple.But five control points can correct image deformation precisely and reliable are not easy particular making 1:500 scale street view map. Nowadays, RTK-GPS becomes the definitive mapping instrument to draw 1:1000 scale maps but get some shortages. That are, 1. Operators can’t have an overall impression of the mapping place. 2 Measuring points are separate so that the lines are not natural and smooth. 3. Data transmission may have 0.1 % mistakes which waste time to check and are troublesome. Given method comes as a substitute, which keeps all advantages and use RTK to definite the key points for drawing. Here are three examples for reference. The map size are extremely large and beyond the custom. (area; 60cm×70cm,80cm×180cm, 60cm×200cm) Which without any splices. The interpolation for rectifying is surface splines which were originally developed for interpolation wing deflections of aircraft; Surface splines are a mathematical tool to interpolate a fuction of two variables. It is Base upon the small deflection equation of an infinite plate. The main adtvantages of the surface splines are that the coordinates of the known points needs not be located in a rectangular array and the function may be differentiated to find slopes. (Contributed by Harderand Desmarais 1972)

Kaiser filter for antialiasing in digital photogrammetry

AbstractImage aliasing is a problem appearing as artefacts in digitally resampled images, which degrades the quality of the image. In digital rectification and texture mapping, pixels from an input image are transformed to pixels of an output image. The discrete nature of a digital image causes aliasing in the transformed image. In this paper the source of aliasing and the theory of antialiasing are described. The necessity of a precise filter design in antialiasing is discussed and a filter based on a Kaiser adjustable window is designed. Different practical antialiasing methods are described as well as interpolation methods, which are conventional in photogrammetry. Selected antialiasing methods are implemented and applied to a close range image. An objective analysis is carried out by applying inverse transformations to rectified images and deriving some measures to estimate the information loss for each method by comparing original and reconstructed images. Results indicate that interpolation methods are not capable of removing or reducing aliasing in highly decimating transformations. The output images of interpolation methods therefore suffer from edge corruption and interfusion of small features. Applying a Kaiser filter with a precise antialiasing method results in the least information loss and considerably reduces aliasing at the expense of higher computation load.

Digital Rectification Techniques for Architectural and Archaeological Presentation

Some exciting developments have been made recently, in the field of digital image rectification, which are of interest to both the photogrammetric specialist and non‐specialist. This paper outlines the technical processes involved in generating digitally rectified images, as well as raising some of the issues that are becoming apparent when applying this modern technology to archaeological and architectural presentation.

Low Cost Digital Rectification on A PC

Digital photogrammetric techniques have opened fresh horizons and have enabled photogrammetry to become a more user friendly tool for a wide range of applications. However cost remains a critical issue, because new digital photogrammetric workstations and their related software are considered expensive. This paper examines the problem of digital rectification and presents low cost solutions involving the use of commercial off the shelf software packages, which include graphics and painting software, image processing tools and a CAD system. Additionally, specially developed software performing vector rectification is described and discussed. All the packages have been used for rectifying digital images and the results are presented. An attempt is also made to assess the accuracy and reliability of the results. Finally, several alternative digital products are presented, mainly concerning the use of the methods described in the restitution of cultural monuments.

Advances in the digital recording of cultural monuments

The last ten years or so have seen rapid advances in the techniques and technologies of photogrammetric imaging and resolution. Many of these advances have been generated by researchers working in the non-conventional areas of photogrammetric applications, including the use of photogrammetric recording as the basis of a documentation tool for cultural sites and monuments. This paper will review modern photogrammetric applications in the recording and documentation of buildings, monuments and sites. These applications include, but are not limited to, digital image enhancement, digital rectification and restitution, the derivation of three-dimensional CAD models from the photogrammetric record and the computer visualisation of cultural monuments. The paper will review research in progress, and give some case studies where photogrammetry is providing an important and successful documentation and investigation service.

Digital image transformation and rectification of spacecraft and radar images

Digital image transformation and rectification can be described in three categories: (1) digital rectification of spacecraft pictures on workable stereoplotters; (2) digital correction of radar image geometry; and (3) digital reconstruction of shaded relief maps and perspective views including stereograms. Digital rectification can make high-oblique pictures workable on stereoplotters that would otherwise not accommodate such extreme tilt angles. It also enables panoramic line-scan geometry to be used to compile contour maps with photogrammetric plotters. Rectifications were digitally processed on both Viking Orbiter and Lander pictures of Mars as well as radar images taken by various radar systems. By merging digital terrain data with image data, perspective and three-dimensional views of Olympus Mons and Tithonium Chasma, also of Mars, are reconstructed through digital image processing.