Christian Seitz | Landesamt für Denkmalpflege Hessen (original) (raw)

Poster by Christian Seitz

Due to demands of precision of 3D documentation and the analysis of such data in historic buildin... more Due to demands of precision of 3D documentation and the analysis of such data in historic building research and archaeology, we present the recently started project "ArchEyeAutomatic" for an automated documentation of historical buildings using Unmanned Aerial Vehicles (UAVs). This is realized by an optimized calculation of a flight trajectory. Financial support is gratefully granted by the German Excellence Initiative within the institutional strategy of the University of Heidelberg and its special funds for Twinning projects.
The previous work consists of two parts. First, the UAV-project "ArchEye", which is used to document excavation areas using a hexa- and octocopter. The software from this project can calculate 2D trajectories for a given ground-resolution by camera-resolution, focal-length and the flight's altitude. The result is a high-resolution orthogonal image which can easily be rectified for further use in a Geographic Information System (GIS).
The second part of the previous work is the photogrammetric Stucture-From-Motion approach. By using this method it is possible to create detailed 3D models of objects just by taking photos in a particular way. The resulting 3D models are useful for an extended documentation in Historic Building Research as well as in Archaeology. With additional software for visualization and analysis like GigaMesh, new insights can be achieved.
To implement an automated acquisition of a building in 3D by an UAV, research in different disciplines is necessary, in this case the specific documentation-methods, robotics, optimization, computer vision and scientific computing.
To acquire the UAV's environment as well as the object to be modeled for the calculation of the trajectory, optical methods like photogrammetry or stereo vision will be applied. The UAV will be represented by a mathematic model. Using these models, the trajectory can be calculated and optimized, solving an Optimal Control Problem in real-time to control the UAV with constraints given by the environment, like obstacles or wind, as well as the UAV but also the 3D model's quality. This is challenging, because the aspect of the model's quality, which is clearly visible for the expert, has to be expressed by a mathematic term. This term is used for optimization of the in real-time calculated next movements for the UAV.
Preliminary results from the project "ArchEye" and some photogrammetric models as well as the plans for the project are shown.

Work at the UNESCO World Heritage Site of Lorsch Abbey has recently been concentrated on the rest... more Work at the UNESCO World Heritage Site of Lorsch Abbey has recently been concentrated on the restauration at the Carolingian King's Hall and the partially preserved medieval church. Therefore both of the buildings were scaffolded and cleaned, giving the possibility to document parts which are usually difficult to reach. During these efforts the capitals, the eave cornice and the frieze of the King's Hall as well as an impost of the church were documented. To calculate a detailed 3D model of the photos the photogrammetric Structure-From-Motion (SFM) approach was used. The employed software "VisualSFM" has been developed by Changchang Wu. For the processing of the resulting pointcloud and the meshing "MeshLab" was used.

The eight capitals where acquired during different visits to the Abbey. In a first step data acquisition of the capitals was realized by using an optical Breuckmann 3D scanner. But due to the bright daylight and the shaky scaffold, the scanning failed. At this point photogrammetry was able to help out and proofed to be a valuable tool for documenting architectural objects in 3D. For each of the eight capitals about 300 photos were taken, resulting in a detailed model.

For each of the four corners of the eave cornice 200 photos were shot. The models show all the details of the cornice. They also reveal a different angle to the current roof, showing it formerly had a flatter roof construction.

The western frieze was photographed for testing purposes, to see if it is possible to acquire a frieze of the whole Hall's length and also around both corners. 474 photos were shot and the model worked well, it shows the entire structure even though it can't display every detail.

The last example shows an impost of the church's arcades. You can see the complete impost now, because the wall which formerly filled the arcades was recently removed. To document it from all sides, 700 photos were taken, resulting in a highly detailed model, showing even little monsters' faces on the frieze of the impost.

Examples of all these models will be shown on the poster as well as analysis using the software framework "GigaMesh" by Hubert Mara (Interdisciplinary Center for Scientific Computing, Heidelberg University) and also a drawing of the capital by Katarina Papajanni (Faculty for Architecture, Technical University Munich).

The ArchEye's Softwareframework combines a workflow out of self developed software using C++ / Qt... more The ArchEye's Softwareframework combines a workflow out of self developed software using C++ / Qt and open source tools (e.g. hugin, QGIS and different 3D-toolkits) Dharamsala, Banteay Chhmar, Cambodia, April 2010 "House of the Guests" built in the late 12th century 5 MPx, single photo, 40 m altitude, Canon Ixus 50 Panoramic view from castle ruin Stahlberg, Germany, 58,7 MPx, 8 photos, about 15-20 m altitude above the ruin, all around view, taken with a

Papers by Christian Seitz

Denkmal Hessen, 2022

Aktuell werden am Landesamt für Denkmalpflege Hessen (LfDH) diverse moderne Methoden und Technike... more Aktuell werden am Landesamt für Denkmalpflege Hessen (LfDH) diverse moderne Methoden und Techniken zur digitalen dreidimensionalen Dokumentation von Kulturerbe angewandt. Diese Methoden decken von der Erfassung sehr kleiner Objekte mit fotogrammetrischer Makrofotografie über die Kleinfundaufnahme mittels handgeführtem Streifenlichtscanner bis hin zur Aufnahme ganzer Bauwerke oder Gärten durch drohnengestütztes Laserscanning und Fotogrammetrie ein sehr breites Spektrum ab. Die so gewonnenen Daten müssen anschließend einer eingehenden Analyse unterzogen werden, um für die weitere Auswertung ein Ergebnis von wissenschaftlichem Mehrwert zu erhalten

Structure from motion (SFM) and unmanned aerial systems (UAS) are two technologies which are well... more Structure from motion (SFM) and unmanned aerial systems (UAS) are two technologies which are well suited for archaeological documentation purposes and complementing each other very well. In the following, we would like to give an overview of the methods, systems, and software available as well as two short practical applications for archaeology and geography. UAS are usually small drones for aerial imaging and video. The UAS section will give an overview on the systems available, restrictions, and challenges, but the focus will be on the capabilities of drones for different purposes. SFM is a subset of the wide field of photogrammetry, using photos to calculate 3D data of the objects pictured. A selection of both free-to-use and commercial software will be introduced, while the main part of the SFM section will be discussing the basic work flow. It covers taking the photos, restoration of the camera positions in 3D space, and creating a surface from the computed point cloud. The com...

Laser scanning point clouds of forest stands were acquired in southwest Germany in 2019 and 2020 ... more Laser scanning point clouds of forest stands were acquired in southwest Germany in 2019 and 2020 from different platforms: an aircraft, an uncrewed aerial vehicle (UAV) and a ground-based tripod. The UAV-borne and airborne laser scanning campaigns cover twelve forest plots of approximately 1 ha. The plots are located in mixed central European forests close to Bretten and Karlsruhe, in the federal state of Baden-Württemberg, Germany. Terrestrial laser scanning was performed in selected locations within the twelve forest plots. Airborne and terrestrial laser scanning point clouds were acquired under leaf-on conditions, UAV-borne laser scans were acquired both under leaf-on and later under leaf-off conditions. In addition to the laser scanning campaigns, forest inventory tree properties (species, height, diameter at breast height, crown base height, crown diameter) were measured in-situ during summer 2019 in six of the twelve 1-ha plots. Single tree point clouds were extracted from the...

Cylinder seals are complex artifacts used in many early administrative systems especially in the ... more Cylinder seals are complex artifacts used in many early administrative systems especially in the Near East and Egypt. They are also linked to religious practices and concepts of identity. Several classical methods can be applied to document these objects, like photography, drawing and molding in plaster or plasticine. In addition to more recent methods like structured light scanning, we present an alternative method for 3D data acquisition. By combining existing technologies in a particular way, seals can be documented fast, cost efficiently and safe from a conservation viewpoint. This method developed at the Interdisciplinary Center for Scientific Computing (IWR) at Heidelberg University is a two-step procedure: first several series of images are obtained with a digital reflex camera in an automated way. The seal is mounted between two soft silicone buffers. An Arduino-based control unit rotates the seal using a stepper motor and triggers the camera. In the second step a 3D reconst...

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2012

In archaeological research the exploration of archaeological monuments from the air has a long tr... more In archaeological research the exploration of archaeological monuments from the air has a long tradition and thus can be seen as a necessary component. At this point our project 'ArchEye' steps in as a cheap and flexible method and also as a new way to document different archaeological areas and objects without using manned aircrafts.

Cylinder seals are complex artifacts used in many early administrative systems especially in the ... more Cylinder seals are complex artifacts used in many early administrative systems especially in the Near East and Egypt. They are also linked to religious practices and concepts of identity. Several classical methods can be applied to document these objects, like photography, drawing and molding in plaster or plasticine. In addition to more recent methods like structured light scanning, we present an alternative method for 3D data acquisition. By combining existing technologies in a particular way, seals can be documented fast, cost efficiently and safe from a conservation viewpoint. This method developed at the Interdisciplinary Center for Scientific Computing (IWR) at Heidelberg University is a two-step procedure: first several series of images are obtained with a digital reflex camera in an automated way. The seal is mounted between two soft silicone buffers. An Arduino-based control unit rotates the seal using a stepper motor and triggers the camera. In the second step a 3D reconstruction of the seal is computed with the photogrammetric structure-from-motion approach. We will show first results acquired with this method both at the Petrie Museum of Egyptian Archaeology and the British Museum in London.

Scientific research concerning castles is most often centred on the object of the castle itself. ... more Scientific research concerning castles is most often centred on the object of the castle itself. Research concerns the history of the castle, its building phases, the structure of the ‘castle’ building or the archaeology of the main castle. The geographical context of the castle is often ignored.
But to understand a castle not only as a building but as part of the social reality of its day it is necessary to put it back into its geographical context. That means to investigate the landscape surrounding the castle and to look at settlements, streets, rivers etc. and their position in the landscape in connection with the castle.

In archaeological research the exploration of archaeological monuments from the air has a long tr... more In archaeological research the exploration of archaeological monuments from the air has a long tradition and thus can be seen as a necessary component. At this point our project ‘ArchEye’ steps in as a cheap and flexible method and also as a new way to document different archaeological areas and objects without using manned aircrafts.

R. Stupperich/H.A. Richter (Editors.) Thetis. Mannheimer Beiträge zur Klassischen Archäologie und Geschichte Griechenlands und Zyperns, 16/17, 2010, 243-245., 2010

Der Quadrokopter besteht aus separat ausgewählten Einzelteilen aus dem Modellbaubereich. Die Steu... more Der Quadrokopter besteht aus separat ausgewählten Einzelteilen aus dem Modellbaubereich. Die Steuer-und Navigationselektronik basiert auf einem großen Open-Source-Projekt. Diese wurde auf Grund der umfangreichen Funktionen und der weit entwickelten Flugsoftware ausgewählt. Dank der großen Nutzergemeinde wird dieser Teil des Systems ständig weiterentwickelt und verbessert.

Talks by Christian Seitz

Under perfect conditions, the best possible Structure from Motion (SfM) 3D model would be achieve... more Under perfect conditions, the best possible Structure from Motion (SfM) 3D model would be achieved by acquiring the largest number of photos using a camera of highest resolution. However, in reality the resolution is limited by the camera used and the time available onsite constrains the total number of images taken. Furthermore these constraints are directly linked to the computational time and quality of the SfM reconstruction.

To determine the dependency between image resolution, number of images, computational time and accuracy of the resulting 3d model, we performed a series of a experiments, which can be categorized in two types: The first set under controlled conditions concerning constant lighting, precise movements between camera and object and accurately measured shapes of the latter to produce quantitatively reliable results. The second set of experiments features application-related objects, such as parts of historic monuments and archaeological small finds.

We examine the relation of camera resolution and number of images taken with the reconstruction time and quality of the model quantitatively. For quality analysis, we use precise models - obtained by a Breuckmann structured light scanner for small objects and a laser scanner for larger objects. Processing time is measured for a set of commercial and free SfM software.

Talk at the ArchaeoBioCenter at LMU Munich on the "Seal rotation device" for semi-automatic docum... more Talk at the ArchaeoBioCenter at LMU Munich on the "Seal rotation device" for semi-automatic documentation of cylindric seals in 3D using Structure-from-Motion and a rotation device.

"In this presentation we will show the ongoing fieldwork and also the results of the “Project Arc... more "In this presentation we will show the ongoing fieldwork and also the results of the “Project ArchEye“ and also introduce it’s follow-up project „ArchEyeAutomatic“.

“Project ArchEye” was started back in 2009 using an Unmanned Aerial Vehicle (UAV), in this case a so called quadrocopter or quadrotor, to document archaeological excavations with high-resolution imagery created from a photo-mosaic. Therefore the author developed a program to calculate a trajectory over the excavation. The user can adjust the resulting pixel resolution on the ground by the data of the camera, the lens and the flight altitude.
We build a better system in 2013, having now both a hexacopter and an octocopter.

In October 2013 the author started his PhD at the research group “Optimization in Robotics and Biomechanics” (ORB) at the “Interdisciplinary Centre for Scientific Computing” (IWR) at the University of Heidelberg. It is an interdisciplinary project, combining Robotics and Computer Science with Building Archaeology and Field Archaeology. Prof. Katja Mombaur (ORB) and Prof. Matthias Untermann (Institute for European Art History, University of Heidelberg) supervise the project. Financial support is gratefully granted by the German Excellence Initiative within the institutional strategy of the University of Heidelberg and its special funds for twinning projects.
We plan to use the UAVs for automated documentation of historic monuments by applying methods of Computer Vision, Robotics, Mathematical Modeling and Optimization, linked by means of Scientific Computing.
The basic idea is to first acquire an overview 3-D model of the area using Stereo Vision. Based on this sparse model, an optimized trajectory for the UAV will be planned, so the whole object will be measured in an automated and complete way. There have to be respected several aspects for the optimization of the trajectory, like the quality of the acquired data, details to record and also the flight distance. This makes the resulting data valuable for scientific interpretation in means of documenting historic monuments."

In der archäologischen Forschung hat die Erkundung von Bodendenkmälern aus der Luft eine lange Tr... more In der archäologischen Forschung hat die Erkundung von Bodendenkmälern aus der Luft eine lange Tradition und ist ein notwendiger Bestandteil. Im Gegensatz zur Erkundung neuer Bodenbefunde wird diese Technik – ebenso wie andere verfügbare Wege – nur selten für die Dokumentation laufender Grabungen oder zur Forschung an Baudenkmälern benutzt, obwohl Senkrechtfotos sehr wertvoll für die Dokumentation sind. Mögliche Gründe dafür sind z.B. erhöhte Kosten vorhandener Techniken vor allem bei konventionellen Luftbildaufnahmen sowie lange Vorbereitungszeiten für den Einsatz anderer Methoden wie einem kleinen Zeppelin.
Hier setzt unser Projekt ArchEye als günstige und flexible Möglichkeit an: Die Basis bildet momentan ein Quadrokopter aus dem Modellbaubereich zur Erzeugung von qualitativ hochwertigen Fotos. Die montierte Spiegelreflexkamera kann mit einer speziellen Halterung geschwenkt werden, so dass die Kamera in beliebigem Winkel, von senkrecht bis horizontal, Fotos machen kann. Das Fluggerät hat einen Durchmesser von nur 60 cm und ermöglicht einen einfachen Transport in einer Alubox sowie einen schnellen und flexiblen Aufbau, da nach dem Ausladen nur noch die Propeller montiert werden müssen. Mit einer digitalen Spiegelreflexkamera sind dabei momentan Flugzeiten von 10–20 Minuten pro Akkuladung möglich.
Gerade der Einsatz herkömmlicher Modellbauteile erlaubt es, im Vergleich zu anderen Projekten dieser Art die Kosten für die Hardware vergleichsweise niedrig zu halten. Ein großer Vorteil der kompakten und leichten Bauweise ist, dass ArchEye nahezu überall eingesetzt werden kann – auch innerhalb der Stadt und sogar in Gebäuden. Bereiche in denen nicht geflogen werden darf, sind typischerweise Gebiete in der Nähe von Flughäfen.
Die einzelnen Fotos werden aus nicht allzu großer Höhe, circa 50–100 m, entlang einer vorher einprogrammierten Wegpunktstrecke aufgenommen. Anschließend werden sie in der Nachbearbeitung halbautomatisch zu einem hochauflösenden digitalen Foto zusammengefügt. Die Software übernimmt zusätzlich auch die im Vorhinein notwendigen Berechnungen der benötigten Flughöhe und des Flugpfades. Diese hängen sowohl von der verwendeten Kamera und dem Objektiv als auch von der gewünschten Auflösung ab. Mit Hilfe auf dem Boden aufgebrachter Passpunkte kann dieses Foto schließlich entsprechend entzerrt und in die bestehende – digitale oder analoge – Dokumentation nahtlos eingefügt werden.
Als Beispiele unserer Arbeit präsentieren wir die Ergebnisse der Flüge auf einer Grabung in der Nähe von Ludwigshafen, zwei Beispiele aus Kambodscha sowie zwei Burgen in der Eifel. Aufgrund der guten Ergebnisse ist die Anbindung von weiteren Methoden, wie zum Beispiel Photogrammetrie, geplant.

Online Articles by Christian Seitz

The UNESCO World Heritage Site of Lorsch Abbey is located in Hesse roughly between Heidelberg and... more The UNESCO World Heritage Site of Lorsch Abbey is located in Hesse roughly between Heidelberg and Frankfurt/Main, Germany. Laser scanners generating 3D point clouds of the structure and photogrammetric Structure-from-Motion (SfM) approaches were used to study and create 3D models. Unmanned aerial vehicle (UAVs) were also employed to support restoration work. This project is continuing with current surveying, measurement and imaging this summer.

Posters by Christian Seitz

Poster presented at CAA 2017 in Heidelberg.

Due to demands of precision of 3D documentation and the analysis of such data in historic buildin... more Due to demands of precision of 3D documentation and the analysis of such data in historic building research and archaeology, we present the recently started project "ArchEyeAutomatic" for an automated documentation of historical buildings using Unmanned Aerial Vehicles (UAVs). This is realized by an optimized calculation of a flight trajectory. Financial support is gratefully granted by the German Excellence Initiative within the institutional strategy of the University of Heidelberg and its special funds for Twinning projects.
The previous work consists of two parts. First, the UAV-project "ArchEye", which is used to document excavation areas using a hexa- and octocopter. The software from this project can calculate 2D trajectories for a given ground-resolution by camera-resolution, focal-length and the flight's altitude. The result is a high-resolution orthogonal image which can easily be rectified for further use in a Geographic Information System (GIS).
The second part of the previous work is the photogrammetric Stucture-From-Motion approach. By using this method it is possible to create detailed 3D models of objects just by taking photos in a particular way. The resulting 3D models are useful for an extended documentation in Historic Building Research as well as in Archaeology. With additional software for visualization and analysis like GigaMesh, new insights can be achieved.
To implement an automated acquisition of a building in 3D by an UAV, research in different disciplines is necessary, in this case the specific documentation-methods, robotics, optimization, computer vision and scientific computing.
To acquire the UAV's environment as well as the object to be modeled for the calculation of the trajectory, optical methods like photogrammetry or stereo vision will be applied. The UAV will be represented by a mathematic model. Using these models, the trajectory can be calculated and optimized, solving an Optimal Control Problem in real-time to control the UAV with constraints given by the environment, like obstacles or wind, as well as the UAV but also the 3D model's quality. This is challenging, because the aspect of the model's quality, which is clearly visible for the expert, has to be expressed by a mathematic term. This term is used for optimization of the in real-time calculated next movements for the UAV.
Preliminary results from the project "ArchEye" and some photogrammetric models as well as the plans for the project are shown.

Work at the UNESCO World Heritage Site of Lorsch Abbey has recently been concentrated on the rest... more Work at the UNESCO World Heritage Site of Lorsch Abbey has recently been concentrated on the restauration at the Carolingian King's Hall and the partially preserved medieval church. Therefore both of the buildings were scaffolded and cleaned, giving the possibility to document parts which are usually difficult to reach. During these efforts the capitals, the eave cornice and the frieze of the King's Hall as well as an impost of the church were documented. To calculate a detailed 3D model of the photos the photogrammetric Structure-From-Motion (SFM) approach was used. The employed software "VisualSFM" has been developed by Changchang Wu. For the processing of the resulting pointcloud and the meshing "MeshLab" was used.

The eight capitals where acquired during different visits to the Abbey. In a first step data acquisition of the capitals was realized by using an optical Breuckmann 3D scanner. But due to the bright daylight and the shaky scaffold, the scanning failed. At this point photogrammetry was able to help out and proofed to be a valuable tool for documenting architectural objects in 3D. For each of the eight capitals about 300 photos were taken, resulting in a detailed model.

For each of the four corners of the eave cornice 200 photos were shot. The models show all the details of the cornice. They also reveal a different angle to the current roof, showing it formerly had a flatter roof construction.

The western frieze was photographed for testing purposes, to see if it is possible to acquire a frieze of the whole Hall's length and also around both corners. 474 photos were shot and the model worked well, it shows the entire structure even though it can't display every detail.

The last example shows an impost of the church's arcades. You can see the complete impost now, because the wall which formerly filled the arcades was recently removed. To document it from all sides, 700 photos were taken, resulting in a highly detailed model, showing even little monsters' faces on the frieze of the impost.

Examples of all these models will be shown on the poster as well as analysis using the software framework "GigaMesh" by Hubert Mara (Interdisciplinary Center for Scientific Computing, Heidelberg University) and also a drawing of the capital by Katarina Papajanni (Faculty for Architecture, Technical University Munich).

The ArchEye's Softwareframework combines a workflow out of self developed software using C++ / Qt... more The ArchEye's Softwareframework combines a workflow out of self developed software using C++ / Qt and open source tools (e.g. hugin, QGIS and different 3D-toolkits) Dharamsala, Banteay Chhmar, Cambodia, April 2010 "House of the Guests" built in the late 12th century 5 MPx, single photo, 40 m altitude, Canon Ixus 50 Panoramic view from castle ruin Stahlberg, Germany, 58,7 MPx, 8 photos, about 15-20 m altitude above the ruin, all around view, taken with a

Denkmal Hessen, 2022

Aktuell werden am Landesamt für Denkmalpflege Hessen (LfDH) diverse moderne Methoden und Technike... more Aktuell werden am Landesamt für Denkmalpflege Hessen (LfDH) diverse moderne Methoden und Techniken zur digitalen dreidimensionalen Dokumentation von Kulturerbe angewandt. Diese Methoden decken von der Erfassung sehr kleiner Objekte mit fotogrammetrischer Makrofotografie über die Kleinfundaufnahme mittels handgeführtem Streifenlichtscanner bis hin zur Aufnahme ganzer Bauwerke oder Gärten durch drohnengestütztes Laserscanning und Fotogrammetrie ein sehr breites Spektrum ab. Die so gewonnenen Daten müssen anschließend einer eingehenden Analyse unterzogen werden, um für die weitere Auswertung ein Ergebnis von wissenschaftlichem Mehrwert zu erhalten

Structure from motion (SFM) and unmanned aerial systems (UAS) are two technologies which are well... more Structure from motion (SFM) and unmanned aerial systems (UAS) are two technologies which are well suited for archaeological documentation purposes and complementing each other very well. In the following, we would like to give an overview of the methods, systems, and software available as well as two short practical applications for archaeology and geography. UAS are usually small drones for aerial imaging and video. The UAS section will give an overview on the systems available, restrictions, and challenges, but the focus will be on the capabilities of drones for different purposes. SFM is a subset of the wide field of photogrammetry, using photos to calculate 3D data of the objects pictured. A selection of both free-to-use and commercial software will be introduced, while the main part of the SFM section will be discussing the basic work flow. It covers taking the photos, restoration of the camera positions in 3D space, and creating a surface from the computed point cloud. The com...

Laser scanning point clouds of forest stands were acquired in southwest Germany in 2019 and 2020 ... more Laser scanning point clouds of forest stands were acquired in southwest Germany in 2019 and 2020 from different platforms: an aircraft, an uncrewed aerial vehicle (UAV) and a ground-based tripod. The UAV-borne and airborne laser scanning campaigns cover twelve forest plots of approximately 1 ha. The plots are located in mixed central European forests close to Bretten and Karlsruhe, in the federal state of Baden-Württemberg, Germany. Terrestrial laser scanning was performed in selected locations within the twelve forest plots. Airborne and terrestrial laser scanning point clouds were acquired under leaf-on conditions, UAV-borne laser scans were acquired both under leaf-on and later under leaf-off conditions. In addition to the laser scanning campaigns, forest inventory tree properties (species, height, diameter at breast height, crown base height, crown diameter) were measured in-situ during summer 2019 in six of the twelve 1-ha plots. Single tree point clouds were extracted from the...

Cylinder seals are complex artifacts used in many early administrative systems especially in the ... more Cylinder seals are complex artifacts used in many early administrative systems especially in the Near East and Egypt. They are also linked to religious practices and concepts of identity. Several classical methods can be applied to document these objects, like photography, drawing and molding in plaster or plasticine. In addition to more recent methods like structured light scanning, we present an alternative method for 3D data acquisition. By combining existing technologies in a particular way, seals can be documented fast, cost efficiently and safe from a conservation viewpoint. This method developed at the Interdisciplinary Center for Scientific Computing (IWR) at Heidelberg University is a two-step procedure: first several series of images are obtained with a digital reflex camera in an automated way. The seal is mounted between two soft silicone buffers. An Arduino-based control unit rotates the seal using a stepper motor and triggers the camera. In the second step a 3D reconst...

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2012

In archaeological research the exploration of archaeological monuments from the air has a long tr... more In archaeological research the exploration of archaeological monuments from the air has a long tradition and thus can be seen as a necessary component. At this point our project 'ArchEye' steps in as a cheap and flexible method and also as a new way to document different archaeological areas and objects without using manned aircrafts.

Cylinder seals are complex artifacts used in many early administrative systems especially in the ... more Cylinder seals are complex artifacts used in many early administrative systems especially in the Near East and Egypt. They are also linked to religious practices and concepts of identity. Several classical methods can be applied to document these objects, like photography, drawing and molding in plaster or plasticine. In addition to more recent methods like structured light scanning, we present an alternative method for 3D data acquisition. By combining existing technologies in a particular way, seals can be documented fast, cost efficiently and safe from a conservation viewpoint. This method developed at the Interdisciplinary Center for Scientific Computing (IWR) at Heidelberg University is a two-step procedure: first several series of images are obtained with a digital reflex camera in an automated way. The seal is mounted between two soft silicone buffers. An Arduino-based control unit rotates the seal using a stepper motor and triggers the camera. In the second step a 3D reconstruction of the seal is computed with the photogrammetric structure-from-motion approach. We will show first results acquired with this method both at the Petrie Museum of Egyptian Archaeology and the British Museum in London.

Scientific research concerning castles is most often centred on the object of the castle itself. ... more Scientific research concerning castles is most often centred on the object of the castle itself. Research concerns the history of the castle, its building phases, the structure of the ‘castle’ building or the archaeology of the main castle. The geographical context of the castle is often ignored.
But to understand a castle not only as a building but as part of the social reality of its day it is necessary to put it back into its geographical context. That means to investigate the landscape surrounding the castle and to look at settlements, streets, rivers etc. and their position in the landscape in connection with the castle.

In archaeological research the exploration of archaeological monuments from the air has a long tr... more In archaeological research the exploration of archaeological monuments from the air has a long tradition and thus can be seen as a necessary component. At this point our project ‘ArchEye’ steps in as a cheap and flexible method and also as a new way to document different archaeological areas and objects without using manned aircrafts.

R. Stupperich/H.A. Richter (Editors.) Thetis. Mannheimer Beiträge zur Klassischen Archäologie und Geschichte Griechenlands und Zyperns, 16/17, 2010, 243-245., 2010

Der Quadrokopter besteht aus separat ausgewählten Einzelteilen aus dem Modellbaubereich. Die Steu... more Der Quadrokopter besteht aus separat ausgewählten Einzelteilen aus dem Modellbaubereich. Die Steuer-und Navigationselektronik basiert auf einem großen Open-Source-Projekt. Diese wurde auf Grund der umfangreichen Funktionen und der weit entwickelten Flugsoftware ausgewählt. Dank der großen Nutzergemeinde wird dieser Teil des Systems ständig weiterentwickelt und verbessert.

Under perfect conditions, the best possible Structure from Motion (SfM) 3D model would be achieve... more Under perfect conditions, the best possible Structure from Motion (SfM) 3D model would be achieved by acquiring the largest number of photos using a camera of highest resolution. However, in reality the resolution is limited by the camera used and the time available onsite constrains the total number of images taken. Furthermore these constraints are directly linked to the computational time and quality of the SfM reconstruction.

To determine the dependency between image resolution, number of images, computational time and accuracy of the resulting 3d model, we performed a series of a experiments, which can be categorized in two types: The first set under controlled conditions concerning constant lighting, precise movements between camera and object and accurately measured shapes of the latter to produce quantitatively reliable results. The second set of experiments features application-related objects, such as parts of historic monuments and archaeological small finds.

We examine the relation of camera resolution and number of images taken with the reconstruction time and quality of the model quantitatively. For quality analysis, we use precise models - obtained by a Breuckmann structured light scanner for small objects and a laser scanner for larger objects. Processing time is measured for a set of commercial and free SfM software.

Talk at the ArchaeoBioCenter at LMU Munich on the "Seal rotation device" for semi-automatic docum... more Talk at the ArchaeoBioCenter at LMU Munich on the "Seal rotation device" for semi-automatic documentation of cylindric seals in 3D using Structure-from-Motion and a rotation device.

"In this presentation we will show the ongoing fieldwork and also the results of the “Project Arc... more "In this presentation we will show the ongoing fieldwork and also the results of the “Project ArchEye“ and also introduce it’s follow-up project „ArchEyeAutomatic“.

“Project ArchEye” was started back in 2009 using an Unmanned Aerial Vehicle (UAV), in this case a so called quadrocopter or quadrotor, to document archaeological excavations with high-resolution imagery created from a photo-mosaic. Therefore the author developed a program to calculate a trajectory over the excavation. The user can adjust the resulting pixel resolution on the ground by the data of the camera, the lens and the flight altitude.
We build a better system in 2013, having now both a hexacopter and an octocopter.

In October 2013 the author started his PhD at the research group “Optimization in Robotics and Biomechanics” (ORB) at the “Interdisciplinary Centre for Scientific Computing” (IWR) at the University of Heidelberg. It is an interdisciplinary project, combining Robotics and Computer Science with Building Archaeology and Field Archaeology. Prof. Katja Mombaur (ORB) and Prof. Matthias Untermann (Institute for European Art History, University of Heidelberg) supervise the project. Financial support is gratefully granted by the German Excellence Initiative within the institutional strategy of the University of Heidelberg and its special funds for twinning projects.
We plan to use the UAVs for automated documentation of historic monuments by applying methods of Computer Vision, Robotics, Mathematical Modeling and Optimization, linked by means of Scientific Computing.
The basic idea is to first acquire an overview 3-D model of the area using Stereo Vision. Based on this sparse model, an optimized trajectory for the UAV will be planned, so the whole object will be measured in an automated and complete way. There have to be respected several aspects for the optimization of the trajectory, like the quality of the acquired data, details to record and also the flight distance. This makes the resulting data valuable for scientific interpretation in means of documenting historic monuments."

In der archäologischen Forschung hat die Erkundung von Bodendenkmälern aus der Luft eine lange Tr... more In der archäologischen Forschung hat die Erkundung von Bodendenkmälern aus der Luft eine lange Tradition und ist ein notwendiger Bestandteil. Im Gegensatz zur Erkundung neuer Bodenbefunde wird diese Technik – ebenso wie andere verfügbare Wege – nur selten für die Dokumentation laufender Grabungen oder zur Forschung an Baudenkmälern benutzt, obwohl Senkrechtfotos sehr wertvoll für die Dokumentation sind. Mögliche Gründe dafür sind z.B. erhöhte Kosten vorhandener Techniken vor allem bei konventionellen Luftbildaufnahmen sowie lange Vorbereitungszeiten für den Einsatz anderer Methoden wie einem kleinen Zeppelin.
Hier setzt unser Projekt ArchEye als günstige und flexible Möglichkeit an: Die Basis bildet momentan ein Quadrokopter aus dem Modellbaubereich zur Erzeugung von qualitativ hochwertigen Fotos. Die montierte Spiegelreflexkamera kann mit einer speziellen Halterung geschwenkt werden, so dass die Kamera in beliebigem Winkel, von senkrecht bis horizontal, Fotos machen kann. Das Fluggerät hat einen Durchmesser von nur 60 cm und ermöglicht einen einfachen Transport in einer Alubox sowie einen schnellen und flexiblen Aufbau, da nach dem Ausladen nur noch die Propeller montiert werden müssen. Mit einer digitalen Spiegelreflexkamera sind dabei momentan Flugzeiten von 10–20 Minuten pro Akkuladung möglich.
Gerade der Einsatz herkömmlicher Modellbauteile erlaubt es, im Vergleich zu anderen Projekten dieser Art die Kosten für die Hardware vergleichsweise niedrig zu halten. Ein großer Vorteil der kompakten und leichten Bauweise ist, dass ArchEye nahezu überall eingesetzt werden kann – auch innerhalb der Stadt und sogar in Gebäuden. Bereiche in denen nicht geflogen werden darf, sind typischerweise Gebiete in der Nähe von Flughäfen.
Die einzelnen Fotos werden aus nicht allzu großer Höhe, circa 50–100 m, entlang einer vorher einprogrammierten Wegpunktstrecke aufgenommen. Anschließend werden sie in der Nachbearbeitung halbautomatisch zu einem hochauflösenden digitalen Foto zusammengefügt. Die Software übernimmt zusätzlich auch die im Vorhinein notwendigen Berechnungen der benötigten Flughöhe und des Flugpfades. Diese hängen sowohl von der verwendeten Kamera und dem Objektiv als auch von der gewünschten Auflösung ab. Mit Hilfe auf dem Boden aufgebrachter Passpunkte kann dieses Foto schließlich entsprechend entzerrt und in die bestehende – digitale oder analoge – Dokumentation nahtlos eingefügt werden.
Als Beispiele unserer Arbeit präsentieren wir die Ergebnisse der Flüge auf einer Grabung in der Nähe von Ludwigshafen, zwei Beispiele aus Kambodscha sowie zwei Burgen in der Eifel. Aufgrund der guten Ergebnisse ist die Anbindung von weiteren Methoden, wie zum Beispiel Photogrammetrie, geplant.

The UNESCO World Heritage Site of Lorsch Abbey is located in Hesse roughly between Heidelberg and... more The UNESCO World Heritage Site of Lorsch Abbey is located in Hesse roughly between Heidelberg and Frankfurt/Main, Germany. Laser scanners generating 3D point clouds of the structure and photogrammetric Structure-from-Motion (SfM) approaches were used to study and create 3D models. Unmanned aerial vehicle (UAVs) were also employed to support restoration work. This project is continuing with current surveying, measurement and imaging this summer.

Poster presented at CAA 2017 in Heidelberg.

DigitalGeoAeoarchaeology 2013

Work at the UNESCO World Heritage Site of Lorsch Abbey has recently been concentrated on the rest... more Work at the UNESCO World Heritage Site of Lorsch Abbey has recently been concentrated on the restauration at the Carolingian King's Hall and the partially preserved medieval church. Therefore both of the buildings were scaffolded and cleaned, giving the possibility to document parts which are usually difficult to reach. During these efforts the capitals, the eave cornice and the frieze of the King's Hall as well as an impost of the church were documented. To calculate a detailed 3D model of the photos the photogrammetric Structure-From-Motion (SFM) approach was used. The employed software "VisualSFM" has been developed by Changchang Wu. For the processing of the resulting pointcloud and the meshing "MeshLab" was used.

The eight capitals where acquired during different visits to the Abbey. In a first step data acquisition of the capitals was realized by using an optical Breuckmann 3D scanner. But due to the bright daylight and the shaky scaffold, the scanning failed. At this point photogrammetry was able to help out and proofed to be a valuable tool for documenting architectural objects in 3D. For each of the eight capitals about 300 photos were taken, resulting in a detailed model.

For each of the four corners of the eave cornice 200 photos were shot. The models show all the details of the cornice. They also reveal a different angle to the current roof, showing it formerly had a flatter roof construction.

The western frieze was photographed for testing purposes, to see if it is possible to acquire a frieze of the whole Hall's length and also around both corners. 474 photos were shot and the model worked well, it shows the entire structure even though it can't display every detail.

The last example shows an impost of the church's arcades. You can see the complete impost now, because the wall which formerly filled the arcades was recently removed. To document it from all sides, 700 photos were taken, resulting in a highly detailed model, showing even little monsters' faces on the frieze of the impost.

Examples of all these models will be shown on the poster as well as analysis using the software framework "GigaMesh" by Hubert Mara (Interdisciplinary Center for Scientific Computing, Heidelberg University) and also a drawing of the capital by Katarina Papajanni (Faculty for Architecture, Technical University Munich)

Digital Geoarchaeology, 2017

Structure from motion (SFM) and unmanned aerial systems (UAS) are two technologies which are well... more Structure from motion (SFM) and unmanned aerial systems (UAS) are two technologies which are well suited for archaeological documentation purposes and complementing each other very well. In the following, we would like to give an overview of the methods, systems, and software available as well as two short practical applications for archaeology and geography. UAS are usually small drones for aerial imaging and video. The UAS section will give an overview on the systems available, restrictions, and challenges, but the focus will be on the capabilities of drones for different purposes. SFM is a subset of the wide field of photogrammetry, using photos to calculate 3D data of the objects pictured. A selection of both free-to-use and commercial software will be introduced, while the main part of the SFM section will be discussing the basic work flow. It covers taking the photos, restoration of the camera positions in 3D space, and creating a surface from the computed point cloud. The combination of both techniques to create 3D models of places or parts of buildings barely reachable is addressed then. Examples from excavations and the documentation of the King’s Hall at the UNESCO World Heritage Site Lorsch Abbey will follow. The last part will show the future possibilities with new technologies, new software, and some challenges for the future.

Field archaeology is a science in which the objects of study are often destroyed during excavatio... more Field archaeology is a science in which the objects of study are often destroyed during excavation. Historical monuments are often threatened by exposure to the elements and other environmental influences. Documentation is therefore indispensable in the former case and an essential part of the conservation process in the latter. Documentation methods are moving more and more into the 3D space, so it makes sense to do more remote sensing in the third dimension as well. The present work is a continuation of the author’s project ArchEye, which was one of the first applications of Unmanned Aerial Vehicles (UAVs) for documentation tasks in archaeology and one of the first archaeological uses of hobbyist multi-copter technology when it started in 2009. It demonstrated the wide range of applications for small drones in archaeology. The experience of this project clearly showed that more automation could improve the efficiency of documentation. Consequently, this thesis approaches this task by leaving behind traditional 2D photo stitching and focusing on 3D recording using Structure from Motion (SfM) with the help of UAVs. The experience of the ground-based SfM approach is outlined in the author’s Master’s thesis entitled "From photos to a 3D model: open-source close range photogrammetry for use in archaeology" formed another essential basis for this work. From the beginning, the aim of this thesis was to achieve a complete method for this approach, because on the one hand a thorough 3D documentation with UAVs and SfM requires specific strategies for the acquisition. On the other hand, the analysis of the resulting 3D data requires tools and knowledge of what can be achieved with them. The limitations of the proposed method are outlined in its specific steps. Therefore, this thesis presents the technical parts of the data acquisition with UAVs and SfM, but also software and methods for documentation, which are elaborated on several examples. To put the results of the approach into perspective, a comparison with other 3D recording methods is shown and discussed.