Dorota Zawieska

A New Approach to the Generation of Orthoimages of Cultural Heritage Objects—Integrating TLS and Image Data

This paper discusses the issue of automation of orthoimage generation based on Terrestrial Laser Scanning (TLS) data and digital images. The following two problems are discussed: automatic generation of projection planes based on TLS data, and automatic orientation of digital images in relation to TLS data. The majority of popular software applications use manual definitions of projection planes. However, the authors propose an original software tool to address the first issue, which defines important planes based on a TLS point cloud utilizing different algorithms (RANdom SAmple Consensus–RANSAC, Hough transform, “region growing”). To address the second task, the authors present a series of algorithms for automated digital image orientation in relation to a point cloud. This is important in cases where scans and images are acquired from different places and at different times. The algorithms utilize Scale Invariant Feature Transform(SIFT) operators in order to find points that correspond in reflectance intensity between coloure images (Red Green Blue—RGB) and orthoimages, based on TLS data. The paper also presents a verification method using SIFT and Speeded-Up Robust Features (SURF) operators. The research results in an original tool and applied Computer Vision(CV) algorithms that improve the process of orthoimage generation.

Computer-aided postural deformity studies using moire and grid projection methods

Two basic optical triangulation systems for routine studies of postural deformities among youths and adults are described. They use projection moire with temporal phase stepping and grating projection with carrier frequency spatial phase stepping for the automatic analysis of fringe patterns. The operation parameters of both systems are discussed and compared. The special medical software developed for analyzing the back and front of the human body is presented.

The analysis of selected orientation methods of architectural objects’ scans

The terrestrial laser scanning is commonly used in different areas, inter alia in modelling architectural objects. One of the most important part of TLS data processing is scans registration. It significantly affects the accuracy of generation of high resolution photogrammetric documentation. This process is time consuming, especially in case of a large number of scans. It is mostly based on an automatic detection and a semi-automatic measurement of control points placed on the object. In case of the complicated historical buildings, sometimes it is forbidden to place survey targets on an object or it may be difficult to distribute survey targets in the optimal way. Such problems encourage the search for the new methods of scan registration which enable to eliminate the step of placing survey targets on the object. In this paper the results of target-based registration method are presented The survey targets placed on the walls of historical chambers of the Museum of King Jan IIIs Palace at Wilanów and on the walls of ruins of the Bishops Castle in Iłża were used for scan orientation. Several variants of orientation were performed, taking into account different placement and different number of survey marks. Afterwards, during next research works, raster images were generated from scans and the SIFT and SURF algorithms for image processing were used to automatically search for corresponding natural points. The case of utilisation of automatically identified points for TLS data orientation was analysed. The results of both methods for TLS data registration were summarized and presented in numerical and graphical forms.

Quality assessment of the TLS data in conservation of monuments

Laser scanning has been recently confirming its high potential in the field of acquiring 3D data for architectural and engineering objects. The objective of this paper is to analyse the quality of the TLS data acquired for different surfaces of monumental objects, with consideration of distances and the scanning angles. Tests concerning the quality of the survey data and shapes of architectural objects, characterised by diversified curvature, structure and the uniformity of the surface, were performed. The obtained results proved that utilisation of terrestrial laser scanning techniques does not allow to achieve expected accuracy for some historical surfaces and it should be substituted by alternative, photogrammetric techniques. Therefore, the typology of constructions of historical objects is important not only for selection of the optimum technique of surveys, but also for its appropriate utilisation. The test objects were architectural details of the Main Hall of the Warsaw University of Technology. Scans were acquired using the 5006h scanner. Diversified geometry of scans was tested, and the relations between the distance and obtained accuracy were specified. In the case of numerous conservational works the precise surface reconstruction is often important, in order to specify damages. Therefore, the repeatability of obtained TLS results for selected surfaces was also tested. Different surfaces were analysed, which are composed of different materials having glittery elements and inhomogeneous structure. The obtained results and performed analyses revealed the high imperfections of the TLS technique applied for measuring surfaces of historical objects. The presented accuracy of measurements of projection of historical surfaces, obtained using the TLS technique may be applied by art conservators, museum professionals, archaeologists and other specialists, to perform wide analyses of historical heritage objects.

Utilisation of laser scanning technology and digital images for measurements of industrial objects - a case study

Abstract Projection of a complicated geometry of industrial objects is the complex issue, which requires properly planned and prepared measurements. Such objects must be accurately inventoried, but their complicated nature often makes the access and the visibility of their entire surface very difficult. Documentation of measurements is often prepared in the form of sketches, plans or maps, which are amended with photographic documentation. The objective of this paper is to test the possibilities to apply laser scanning and the network of digital images for inventory and monitoring of technical conditions of industrial objects. Processing of a precise documentation acquired basing on terrestrial laser scanning data or dense points clouds generated from digital images still causes many difficulties and problems. Although data processing algorithms have been intensively developed with respect to generation of high resolution orthoimages or precise vector drawings, the existing problems are still connected with limitations related to imperfections of both techniques of measurements.

Moire and grating projection techniques for measurement of postural deformity

Detailed investigations of the projection moire and grid projection methods used for the computer aided studies of the shape of the muscle-osseous system and postural deformities are presented. The shape determination process is readily automated using the phase methods for analyzing the fringe patterns. The issue of subtracting the reference surface inherent to the measurement-by-comparison methods is discussed. Specialized medical software for studying the deformity of the back and front of the human body illustrated by clinical examples is presented.

An Example of Multitemporal Photogrammetric Documentation and Spatial Analysis in Process Revitalisation and Urban Planning.

Urban space is undergoing permanent and dynamic transformations resulting from economic and social changes, technological development and migrations of people from rural areas to cities. It strongly affects the evolution of the landscape and city structures. Current photogrammetric techniques allow for the acquisition of data for large areas within a relatively short time, and thus, allow for fast updating and verification of existing data files. The authors of this paper have focused their research on the possibility to use multi-variant spatial analysis in the process of revitalisation of degraded areas in cities. The industrial district of Warsaw was selected for this study, where problems concerning the development of formally industrial areas located in the attractive part of the city (close to the city centre) are extremely visible. As a result of urban development, degraded areas are included within administrative boundaries of the city and have created urban

Development of Photogrammetric Documentation of the Borough at Biskupin Based on Archival Photographs - First Results

This paper presents the initial results of research work carried out as part of a project entitled “The design of development of the Lusatian culture settlement at Site 4 at Biskupin: pre-war research work” financed by the Ministry of Culture and National Heritage, within the National Heritage 2016 Programme, “Conservation of archaeological monuments”. The high quality of photographic documents results from the professional, technical and organizational facilities organized by the Biskupin Expedition during the period 1934-1939. A group of photographs acquired from various heights at that time were selected (an aeroplane, a barrage balloon, an observational balloon and terrestrial photographs); these were used for further processing. Using photographs, a true orthoimage, 3D vector models and a 3D visualization of photorealistic models were generated. This paper presents the methodology and stages of the technological process of generation of photogrammetric documentation based on archival data. The benefits and disadvantages of the conventional photogrammetric approach are discussed, and a modified approach involving the application of commonly-used computer vision algorithms is also presented.

Photogrammetry at the Warsaw University Of Technology – past and present

Abstract The Department of Photogrammetry, Remote Sensing and Geographic Information Systems at the Warsaw University of Technology is one of six organizational units of the Faculty of Geodesy and Cartography. The photogrammetry has been under interest of scientists in Faculty for over 90 years. The last decades has been characterized by the incredible development of photogrammetric technologies, mainly towards wide automation and popularization of derivative products for processing data acquired at satellite, aerial, and terrestrial levels. The paper presents achievements of scientists employed in Photogrammetric Research Group during last decades related to projects that were carried out in this department.

Comparative postural deformity studies by photogrammetric methods with structural illumination

Detailed investigations of the projection moire and grid projection methods used for the computer aided studies of the shape of the muscle-osseous system and postural deformities are presented. The shape determination process is readily automated using the phase methods for analyzing the fringe patterns. The issue of subtracting the reference surface inherent to the measurement-by-comparison methods is discussed. Specialized medical software for studying the deformity of the back and front of the human body illustrated by clinical examples is presented.