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Karel Pavelka

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Professor, Czech Technical University in Prague, Faculty of Civil Engineering, dept. of geomatics. I am specialized on photogrammetry, remote sensing, laser scanning, 3D documentation of cultural heritage, gepophysical methods.

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Papers by Karel Pavelka

New Low-Cost Automated Processing of Digital Photos for Documentation and Visualisation of the Cultural Heritage

Geoinformatics FCE CTU, Dec 21, 2011

The 3D scanning is nowadays a commonly used and fast technique. A variety of type's 3D scanners i... more The 3D scanning is nowadays a commonly used and fast technique. A variety of type's 3D scanners is available, with different precision and aim of using. From normal user´s point of view, all the instruments are very expensive and need special software for processing the measured data. Also transportation of 3D scannersposes a problem, because duty or special taxes for transport out of the EU have to be paid and there is a risk of damage to dismantling of these very expensive instruments and calibration will be needed. For this reason, a simple and automated technique using close range photogrammetry documentation is very important. This paper describes our experience with the software solution for automatic image correlation techniques and their utilization in close range photogrammetry and historical objects documentation. Non-photogrammetrical approach, which often gives very good outputs, is described the last part of this contribution. An image correlation proceeds well only on appropriate parts of documented objects and depends on the number of images, their overlapping and configuration, radiometrical quality of photos, and surface texture.

Different Data Joining as a Basic Model for Hbim – a Case Project St. Pataleimon in Skopje

The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Jun 13, 2023

H-BIM (Heritage Building Information Modelling) is principle and system of use of historic buildi... more H-BIM (Heritage Building Information Modelling) is principle and system of use of historic buildings that can be used for the management, reconstruction or renovation and restoration of monuments. It is a set of geometric and descriptive information about a building. In the last decade, several historical objects were documented using modern methods, mainly advanced photogrammetrical and laser technologies, for a wide range of users to get benefits from economically, safety, presentation, and life cycle management of historical buildings. The rapid development in geomatics is possible thanks to advanced technologies of data capturing, sufficient capacity of computer technology and transmission and information networks. The most used technologies are terrestrial laser scanning (TLS), personal laser scanning (PLS) or mobile mapping systems (MMS), terrestrial or aerial drone based close-range digital photogrammetry (using SfM -structure from motion technology and MVS -multi view stereo). Today's modern advanced technologies allow geometrical and textural data collection within a few centimetres' accuracy outside and inside infrastructure by various methods of PLS, photogrammetrical SfM and TLS. In terms of object visualisation, VR or AR (virtual or augmented reality) technology is proving to be suitable. The following text discusses the use of geomatics technologies for the creation of H-BIM on the example of a cultural monument in Skopje, North Macedonia, including visualization in virtual reality (VR).

Modern Methods of Documentation and Visualization of Historical Mines in the Unesco Mining Region in the Ore Mountains

ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Jun 23, 2023

The article focuses on modern methods of mining activity documentation and visualization. The dev... more The article focuses on modern methods of mining activity documentation and visualization. The development of technologies that allow us to display 3D models are many in recent years, from web portals, augmented reality using smartphones or tablets to virtual reality glasses. These technologies give us a whole new way of looking at and viewing 3D models. In this study, we will use most of the available options to visualize mining activities in the UNESCO-protected Ore Mountains. Each of these technologies needs differently prepared data. Because each of these technologies have different limits, we need to find these limits and modify the 3D models. The ZEB Revo laser scanner was used for data acquisition, which uses SLAM technology and is much more suitable for such areas than conventional terrestrial scanners, with which the work is lengthy and not nearly as efficient, and not the least of which eliminates the time-consuming post-scan work of merging scans. Especially when using scanning for mining, where there is not quite enough to go around, manually splicing scans is a nightmare, and automatic post-production merging is also often problematic.

Ice Elevation Change Based on GNSS Measurements along the Korth-Traverse in Southern Greenland

Applied sciences, Nov 25, 2022

In 1912, a Swiss expedition led by meteorologist Alfred de Quervain crossed the Greenland ice she... more In 1912, a Swiss expedition led by meteorologist Alfred de Quervain crossed the Greenland ice sheet on a route from Disko Bay to Tasiilaq. Based on that, in 2002, a series of geodetic expeditions carried out by W. Korth and later by T. Hitziger began along the same traverse as in 1912, with the last measurements taken in May 2021. The statically collected GPS/GNSS data provide very accurate elevation changes at 36 points along the almost 700 km long crossing over a period of 19 years. According to this, there is a maximum increase of 2.1 m in the central area and a decrease of up to 38.7 m towards the coasts (influence Ilulissat Isbrae). By using kinematic GNSS measurements, there is a very dense profile with a spacing of a few meters. The comparison of those measurements is performed using crossing points or minimum distances and gives equivalent results for both methods. It is shown that local ice topography is preserved, and thus gaps in data sets can be caught. Areas of accumulation and ablation on the ice sheet can be identified, showing the widespread influence of outlet glaciers up to 200 km. The data can be used for direct verification of altimetry data, such as IceSat. Both IceSat elevations and their changes can be compared.

Analysis of Possible Geodetic Approaches for 3D Model Creation in Bim

The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Jun 13, 2023

The topic of this paper is the description and analysis of technologies for generating a geometri... more The topic of this paper is the description and analysis of technologies for generating a geometric basis for BIM. The main element is an analysis of the capabilities of mobile laser scanning and the outputs of this method compared to other methods. The selected interior space was measured by different technologies, laser scanning, classical geodetic using total station, and manual measurement. The main device tested was the ZEB-REVO. It is a handheld mobile laser scanner, carried by an operator. It has a range of 40 m, with the accuracy in measured lengths is 1-3cm per 10 m depending on the type of surface. The scanning speed is 43,000 points per second. The device is equipped with an inertial measurement unit (IMU) and uses SLAM technology for trajectory definition. The device does not have a camera in the simplest configuration and the operator cannot monitor the scanning status. Nevertheless, measurement with this scanner is very simple. The instrument is mainly used for surveying construction objects, but it can be advantageously used for documentation of underground spaces or in e.g., forestry for defining DBH or volume of stockpiles. This device is not equipped with a GNSS unit, and the typical scanning time is 20-30 min without model deformation. Accuracy and output analysis was performed for all technologies used. The results are presented in tables and show the suitability of PLS (personal laser scanner) in general.

Visualisation and Animation of Undiscovered Tomb Interior at the Prague Castle

There are many tombs of Czech kings and princes at the Prague Castle. Some remains of the Czech p... more There are many tombs of Czech kings and princes at the Prague Castle. Some remains of the Czech princes and their wives from the Přemysl epoch (9 th century-1306 A.D.) were transported to a new cathedral of St.Vitus (1373) by the emperor and Czech king Charles IV in the Middle Ages. The tombstones were made in the well-known stone workshop of the Parléř family. During war in the year 1757 on wish of Fredrick II., the king of Prussia, some tombs were partly damaged and opened. Majority of the tombs were investigated in the 19 th and 20 th centuries. The tombs of Bořivoj II (1100-1124) and Břetislav II (1092-1100) were restored in 2002. Mixed stones with lime were discovered under the upper part of the tomb; the space for the remains was been found under this layer and under the floor level. In the case of tomb Břetislav II, the prince, the last unknown opening has been stated in the 19 th century (a small lead tablet with the date was found). In the case of Bořivoj II, the prince, the tomb has not been opened for more than 600 years (from the Charles IV time). It is a single undiscovered Přemysl´s tomb at the Prague Castle. This is because of large two stones (2x3m) shield the space over remains in the ground. The decision on status quo has been made after discussions. The reconnaissance using endoscopes has only been allowed. The 3D visualisation of the Bořivoj II tomb interior is the theme of this paper.

Automatic Classification of Point Clouds for Highway Documentation

Acta Polytechnica, Jul 2, 2018

Mobile laser scanning systems confirmed the capability for detailed roadway documentation. Hand i... more Mobile laser scanning systems confirmed the capability for detailed roadway documentation. Hand in hand with enormous datasets acquired by these systems is the increase in the demands on the fast and effective processing of these datasets. The crucial part of the roadway datasets processing, as well as in many other applications, is the extraction of objects of interest from point clouds. In this work, an approach to the rough classification of mobile laser scanning data based on raster image processing techniques is presented. The developed method offers a solution for a computationally low demanding classification of the highway environment. The aim of this method is to provide a background for the easier use of more sophisticated algorithms and a specific analysis. The method is evaluated using different metrics on a 1.8km long dataset obtained by LYNX Mobile Mapper over a highway.

Spatial 3D Documentation of Historical Mining Remnants in Forested Area in the Erzgebirge/Krušnohoří Mining Region Unesco Site

The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Aug 28, 2021

This contribution deals in the possibilities of 3D documentation of historical mining relicts hid... more This contribution deals in the possibilities of 3D documentation of historical mining relicts hidden in the forest. On the Czech -German border, in the Ore Mountains, several historical mining relicts are located there. There are interesting underground spaces (historical mines), some of which have recently been made available for visits by tourists. But there are many relicts on the surface that are linked to mining and are not known or on the fringes of interest. These are mining pits, dumps, water works, remains of buildings and historic entrance roads. Many of them are in forest areas, were not documented or archaeologically explored, and have recently been devastated by amateur collectors equipped with metal detectors who unfortunately destroy unexplored localities to find interesting relicts. For the basic documentation and delimitation of these objects, aerial laser scanning (ALS) and personal laser mobile scanning (PLS) were used; some finds were documented by close-range photogrammetry.

Combined Precise Documentation and Virtual Reconstruction of Prophet Nahum Shrine in Alqosh, Iraq

The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Aug 23, 2019

In today's world, cooperation between companies that specialize in certain processes is important... more In today's world, cooperation between companies that specialize in certain processes is important. There is a long term cooperation between the company GemaArt, focused on historical monument restoration and the Czech Technical University, Faculty of Civil Engineering, dept. of Geomatics, Laboratory of photogrammetry Since 2006, we have finished a lot of projects focused on historical monument care. In the frame of our last project, which was focused on the revitalization and restoration of the Prophet Nahum Shrine in Alqosh in the Iraqi Region of Kurdistan, the detailed documentation and geophysical research of the shrine was carried out in 2018. Close-range photogrammetry, UAV and laser scanning were used for the basic documentation. Several data merge experiments were performed during processing. Significant was the transfer of the main object to the VR, which allows viewing of the object by other professionals without a direct visit to the site and to preserve its original condition before reconstruction.

The Contribution of Geomatic Technologies to Bim

The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Dec 5, 2019

There are many definitions of the commonly used abbreviation BIM, but one can say that each user ... more There are many definitions of the commonly used abbreviation BIM, but one can say that each user or data supplier has different idea about it. There can be an economic view, or other aspects like surveying, material, engineering, maintenance, etc. The common definition says that Building Information Modelling or Building Information Management (BIM) is a digital model representing a physical and functional object with its characteristics. The model serves as a database of object information for its design, construction and operation over its life cycle, i.e. from the initial concept to the removal of the building. BIM is a collection of interconnected digital information in both protected and open formats, recording graphical and non-graphical data on model elements. There are two facets: a) BIM created simultaneously with the project, or project designed directly in BIM (it is typical of new objects designed in CAD systems -for example in the Revit software) or b) BIM for old or historical objects. The former is a modern technology, which is nowadays used worldwide. From the engineer's perspective, the issue is the creation of BIM for older objects. In this case, it is crucial to obtain a precise 3D data set -complex 3D documentation of an object is needed and it is created using various surveying techniques. The most popular technique is laser scanning or digital automatic photogrammetry, from which a point cloud is derived. But this is not the main result. While classical geodesy gives selective localized information, the abovementioned technologies give unselected information and provide huge datasets. Fully automatic technologies that would select important information from the point cloud are still under development. This seems to be a task for the coming years. Large amounts of data can be acquired automatically and quickly, but getting the expected information is another matter. These problems will be analysed in this paper. Data conversion to BIM, especially for older objects, will be shown on several case studies. The first is an older technical building complex transferred to BIM, the second one is a historical building, and the third one will be a historic medieval bridge (Charles Bridge in Prague). The last part of this paper will refer to aspects and benefits of using Virtual Reality in BIM.

Documentation and virtual reconstruction of historical objects in Peru damaged by an earthquake and climatic events

Advances in Geosciences, Jul 3, 2013

This paper deals with the possibilities of creating a 3-D model and a visualization technique for... more This paper deals with the possibilities of creating a 3-D model and a visualization technique for a presentation of historical buildings and sites in Peru. The project Nasca/CTU is documenting historical objects by using several techniques. This paper describes the documentation and the visualization of two historical churches (San Jose and San Xavier Churches) and the pre-Hispanic archaeological site La Ciudad Perdida de Huayuri (Abandoned town near Huayuri) in Nasca region by using photogrammetry and remote sensing. Both churches were damaged by an earthquake. We use different process for the documentation of these objects. Firstly, PhotoModeler software was used for the photogrammetric data processing of the acquired images. The subsequent making models of both churches were different too. Google SketchUp software was used for the San Jose Church and the 3-D model of San Xavier Church was created in MicroStation software. While in the modelling of the "Abandoned town" near Huayuri, which was destroyed by a climatic event (El Niño), the terrestrial photogrammetry, satellite data and GNSS measurement were applied. The general output of the project is a thematic map of this archaeological site; C 14 method was used for dating.

High Resolution Drone Surveying of the Pista Geoglyph in Palpa, Peru

Geosciences, Dec 13, 2018

Currently, satellite images can be used to document historical or archaeological sites in areas t... more Currently, satellite images can be used to document historical or archaeological sites in areas that are distant, dangerous, or expensive to visit, and they can be used instead of basic fieldwork in several cases. Nowadays, they have final resolution on 35-50 cm, which can be limited for searching of fine structures. Results using the analysis of very high resolution (VHR) satellite data and super resolution data from drone on an object nearby Palpa, Peru are discussed in this article. This study is a part of Nasca project focused on using satellite data for documentation and the analysis of the famous geoglyphs in Peru near Palpa and Nasca, and partially on the documentation of other historical objects. The use of drone shows advantages of this technology to achieve high resolution object documentation and analysis, which provide new details. The documented site was the "Pista" geoglyph. Discovering of unknown geoglyphs (a bird, a guinea pig, and other small drawings) was quite significant in the area of the well-known geoglyph. The new data shows many other details, unseen from the surface or from the satellite imagery, and provides the basis for updating current knowledge and theories about the use and construction of geoglyphs.

Structure from Motion Processing of Analogue Images Captured by Rollei Metric Camera, Digitized with Various Scanning Resolution

Acta Polytechnica

SfM processing of archived analogue images gives an opportunity to efficiently create new and val... more SfM processing of archived analogue images gives an opportunity to efficiently create new and valuable 2D and 3D results. The SfM processing of digitized analogue images brings some challenges. How to digitize negatives of photogrammetric images? What scanning resolution is the most beneficial for processing? How to preprocess the digitized images to be able to process them using the SfM method? What accuracy of results is possible to expect? This paper tries to deal with all these questions. For this paper, 7 negatives of former photogrammetric documentation of a vault were chosen. The negatives were captured by Rollei 3003 metric camera in 1999. Two pieces of software were chosen for the SfM processing. A commercial alternative Agisoft PhotoScan and free open-source alternative MicMac. The results of the SfM processing were compared to the results of an original photogrammetric method, which was used for former processing in 1999.

Optimizing Mobile Laser Scanning Accuracy for Urban Applications: A Comparison by Strategy of Different Measured Ground Points

Applied sciences, Apr 17, 2024

This article is an open access article distributed under the terms and conditions of the Creative... more

Transformations in the Photogrammetric Co-Processing of Thermal Infrared Images and RGB Images

Sensors, Jul 26, 2021

This article is an open access article distributed under the terms and conditions of the Creative... more

Photogrammetric Co-Processing of Thermal Infrared Images and RGB Images

Sensors, Feb 20, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more

Relics of Mining Activities in West Bohemia – Mapping by Airborne Laser Scanning

The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Jul 19, 2013

The part of the Czech Republic-West Bohemia is well known for mining activities, different types ... more The part of the Czech Republic-West Bohemia is well known for mining activities, different types of raw materials have been extracted from mines near Jáchymov, Sokolov and other sites since medieval times till today. There are original maps of some sites, as well there is effort of some geologists to find and map relics of mining activities (such as digs visible in terrain) by land survey. The quality of these available maps is unfortunately questionable-due to its age or used methods. Our aim was to find resource useful for searching for these sites, than to use field survey to confirm our findings. We used available digital terrain model (DTM) based on airborne laser scanning (ALS) technology to map relics of mining activities in West Bohemia. The Czech Office for Surveying, Mapping and Cadastre started in 2008 project for terrain mapping using the ALS method. The aim of mapping was to get authentic and detailed DTM of the Czech Republic. About 2/3 of area is currently covered by the DTM based on ALS, this year the mapping should be complete. The dataset is characterised by the density of 1-2 points/m 2 and the standard deviation in altitude of model points is up to 30cm (in forested areas). We had DTM in form of shaded surface for one third of the Czech Republic. The shaded surface enables to highlight terrain break lines, which is suitable for archaeological research. Terrain modifications caused by human activity are characterized by terrain break lines, local tops or pits, which do not fit to local geomorphology. Visual image interpretation of the dataset is in the process.

Photo-Plan Creation of Cylindrical Objects

ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Jul 31, 2013

Photo-plans are frequent outputs in photogrammetry focused on historical planar objects. For plan... more Photo-plans are frequent outputs in photogrammetry focused on historical planar objects. For planar spatially articulated objects it is not possible to create an exact photo-plan but is it possible to make an orthophoto. These above mentioned methods are inappropriate for cylindrical objects. In our contribution, methods of creating photo-plans are evaluated when used for cylindrical objects. This paper deals with today's possibilities, which are available for developable bodies. Commercial software dealing with these issues is introduced and some published procedures of creating photomaps using unwrapping are shown. There are specific given examples of processing and results. A number of historical buildings contain cylindrical elements-such as towers, vaults, and apses. Their documentation is not easy and it is problematic to use the classic single image photogrammetry and popular photo-plan, which contains all photographic details. It seems to be appropriate to unwrap this form into a plane. Subsequently, the paper presents main computational procedures and methods introduced in the Laboratory of Photogrammetry of the CTU in Prague. In the practical part of this paper the software Photo UnWrap and the methods used by authors for unwrapping cylindrical and conical bodies are introduced.

Flying Laboratory of Imaging Systems: Fusion of Airborne Hyperspectral and Laser Scanning for Ecosystem Research

Remote Sensing

Synergies of optical, thermal and laser scanning remotely sensed data provide valuable informatio... more Synergies of optical, thermal and laser scanning remotely sensed data provide valuable information to study the structure and functioning of terrestrial ecosystems. One of the few fully operational airborne multi-sensor platforms for ecosystem research in Europe is the Flying Laboratory of Imaging Systems (FLIS), operated by the Global Change Research Institute of the Czech Academy of Sciences. The system consists of three commercial imaging spectroradiometers. One spectroradiometer covers the visible and near-infrared, and the other covers the shortwave infrared part of the electromagnetic spectrum. These two provide full spectral data between 380–2450 nm, mainly for the assessment of biochemical properties of vegetation, soil and water. The third spectroradiometer covers the thermal long-wave infrared part of the electromagnetic spectrum and allows for mapping of surface emissivity and temperature properties. The fourth instrument onboard is the full waveform laser scanning system...

Complex Archaeological Prospection Using Combination of Non-destructive Techniques

The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2015

This article describes the use of a combination of non-destructive techniques for the complex doc... more This article describes the use of a combination of non-destructive techniques for the complex documentation of a fabulous historical site called Devil's Furrow, an unusual linear formation lying in the landscape of central Bohemia. In spite of many efforts towards interpretation of the formation, its original form and purpose have not yet been explained in a satisfactory manner. The study focuses on the northern part of the furrow which appears to be a dissimilar element within the scope of the whole Devil's Furrow. This article presents detailed description of relics of the formation based on historical map searches and modern investigation methods including airborne laser scanning, aerial photogrammetry (based on airplane and RPAS) and ground-penetrating radar. Airborne laser scanning data and aerial orthoimages acquired by the Czech Office for Surveying, Mapping and Cadastre were used. Other measurements were conducted by our laboratory. Data acquired by various methods provide sufficient information to determine the probable original shape of the formation and proves explicitly the anthropological origin of the northern part of the formation (around village Lipany).