How we build reality

Douglas PritchardAssociate ProfessorSchool of Energy, Geoscience, Infrastructure and SocietyHeriot Watt University, Edinburgh

The Cologne Cathedral is an exceptional building, cer-tainly worthy of its UNESCO World Heritage Site status. It is remarkable that the de-sign of the massive structure dates back to the 13th cen-tury. From 1880 until 1884 it was the tallest freestanding structure in the world. The Cathedral has endured sig-nifi cant challenges over the centuries but contemporary

issues include urban encroachment, regional seismic activity, air pollution, global warming and of course the impact of over 6 million visitors per year. The purpose of the documentation project was to provide the Ca-thedral administration with an exceptionally precise 3D as-built record to assist in the ongoing conserva-tion, condition assessment and management of the structure.

Initiated by at Hochschule Fresenius, in partnership with the Metropolitankapitel der Hohen Domkirche Köln Dombauhütte and Heriot Watt University (Ed-inburgh, Scotland), the Cologne Cathedral was sys-tematically laser scanned using the latest Zoller and Fröhlich scanning technology.

The site work began in May 2015 with the terrestrial scanning of the vast cathedral interior. The scanners were initially positioned at grade, then moved up to various points along the triforium, at the apex of the ribbed vaults, and the upper level loft. The exterior scanning also occurred at grade encircling the entire building, then at the 20 and 27-meter parapet levels, along the roof and at the crossing tower. Particular at-tention was paid to individually capturing the cathe-dral’s fl ying buttresses. All of the work was done with Z+F 5010C and Z+F 5010X terrestrial scanners at ‘Su-per High’ resolution setting with full HDR imagery. To better illuminate the interior surfaces and tapestries during low-light conditions, the scanners were com-plimented with the Z+F Smart Light.

In addition to navigating through the swarm of tour-ists, the biggest challenge of the project was to cap-ture the surface detail of the two enormous Cathedral

3Dom

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towers. The scanner was positioned along the base of the towers at the 100-meter level, then hauled up to the 150-meter lev-els. Similar to previous HWU documentation projects, a custom-designed extension rig was used to position the scanner out from the face of the towers. The scanner was set vertically to capture the top sections of the tow-ers, then inverted to provide a better view of the entirety of the Cathedral roof.

The speed and density of acquired data of the 5010C and 5010X are highly benefi cial, but the ability of hav-ing an integrated laser scanner and high-resolution HDR camera at the same nodal point is particularly benefi cial for challenging scanning projects. The dual-documentation capability allows the scanner to be positioned once and then remotely operated, captur-ing both point data and imagery. A necessary require-ment when extending the scanner out on an exten-sion rig.

By the end of the two phases of the project, approxi-mately 660 full-colour interior and exterior terrestrial scans had been captured. The size of the data has posed particular challenges, but the registration has gone remarkably smoothly. The next production stage is also progressing well with the development of a 3D photorealistic model and as-built CAD documents.

It has been a real privilege to be part of this project and it has been a delight to work with such a wide range of enthusiastic people. The success of this proj-ect is certainly due to collaboration, in particular the highly professional assistance and support from the Cathedral staff, the generous assistance from Zoller and Fröhlich and most certainly Chris Wickenden’s team from Hochschule Fresenius.

Coloured 3D point cloud of the Cathedral‘s interiorPicture: Heriot Watt University

Prof. Chris WickendenAcademic Dean 3D-Design & ManagementFresenius University of Applied Sciences, Cologne

Initially this project was considered an entrance op-portunity into the world of 3D scanning for students of the Fresenius University of Applied Sciences, Co-logne. In 2014 Douglas Pritchard from the Heriot Watt University, Edinburgh and I met at the 3D Symposium in Karlsruhe - credit here to Prof. Ludger Pfanz for set-ting up this opportunity and proving how venues like these offer mass potential for people to meet and dis-cuss projects or visions.

We quickly agreed that the heritage value of the Co-logne Cathedral would meet certain expectations and demands – at the time unaware of the size and volume this gigantic building would supply technically. However, it seemed a welcome challenge and given the support and technical back-up of Zoller + Fröhlich the project never gave reason to doubt the impact it would have if we could deliver quality and precision.

Douglas led the role of technical supervisor and scan-master, while I maintained the role of project supervi-son and coordination in close relationship to the Ca-thedral Conservation Workshop (Dombauhuette) led by architectural engineer Joerg Sperner. The students took great participation in assisting Douglas and the project with disciplined supportive roles and organisa-tion. Adding to this they delivered a quality documen-tary for viral and classic media (www.youtube.com/user/HSFresenius), thus building up the marketing ef-fect and the project´s attention it received throughout the whole of 2015. The local public and the special interest media showed particular concern, either re-garding the symbolic meaning the cathedral has for its locals or the genuine issue of heritage conserva-tion to monitor and serve future restoration ambitions for experts around Germany.

In 2 periods the cathedral endured over 660 high res-olution scans with terrestrial Z+F laser scanners of the IMAGER® 5010 series resulting in over 2 terrabyte of registered data delivered to the Dombauhuette on the historic occasion of 15th March 2016. In May 2015 the fi rst phase covered the complete interior and parts of the outside ground level. Following the examination of this data and the determination of the 2nd phase in November, further 440 scans of the roof and towers were accomplished to secure an overall 3D collection of highly unusual and quality 3D survey data. In both

How we build reality 3Dom

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phases, Z+F and their expert staff showed absolute concern and ambition to guarantee perfect material and deliver precision scans never before achieved for the cathedral.

Massive appreciation also to Christoph Fröhlich who never showed reluctance to offer us immediate sup-port - staff or technical wise – a great company spirit rarely seen these days, as the budget was limited to the scientifi c and documentive commitment of Heriot Watt and Fresenius.

For me, as Professor and Academic Dean of the Fre-senius Bachelor Programme 3D-Design & Manage-ment (initially 3D-Mind & Media), the challenge re-mains how the study programme can possibly benefi t from our initial intention to offer 3D design students an encounter with high technology terrestrial scanning and deliver innovative output from the experience in scientifi c survey on heritage sites.

This project has attracted high attention from a va-riety of experts in politics, heritage, survey and de-sign – most recently also other universities, seeking the opportunity to participate in scientifi c study of 3D modelling of scan data.

The Fresenius students have gained suffi cient knowl-edge regarding project effi ciency, heritage culture, data volume, meshing of point cloud data and tech-nological demands in surveying. Overall, the true ben-efi ts for such an extremely highly sophisticated and demanding project lie in the depth of environmental sociology and how we shall manage the growing dan-ger of destructive willpower, increasing pollution and natural disasters. To open a young design student´s mind for this particular concern and offer them in-sight into a technology of incredible potential like the Z+F scanners is already a big step and added value I honestly hadn’t expected at the time I met Douglas in Karlsruhe.

3D-Design & Management students also covered the scan process as a 20 min. documentary (www.youtube.com/user/HSFresenius)

Picture: Fresenius University of Applied Sciences, Cologne

How we build reality 3Dom

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Philipp KresserMarketingZoller + Fröhlich GmbH, Wangen im Allgäu

Cathedrals unite arts, architec-ture, history and faith like no oth-er place. The Cologne Cathedral is defi nitely amongst the most impressive. The sheer size of the Cathedral as well as count-less delicate structures are only a few of the numerous challeng-es which had to be overcome. Careful planning, expertise, high-

precision equipment and a well-working team were required in order to execute the project smoothly. And all that came together over the two phases.

The entire project was a tre-mendous opportunity to put our equipment to the test in a very challenging environment - es-pecially our new laser scanner, the Z+F IMAGER® 5010X. This scanner is not only equipped with a HDR camera, but also an integrated positioning system. The localization of the scanner is used for the automatic cloud-to-cloud registration in the fi eld. The scanner as well as the new software Z+F LaserControl® Scout allow a revolutionary workfl ow - the so called “Blue Work-fl ow”. This allows the user to take care of all scanning and preprocessing tasks on the fl y - saving time and money. The technology came in very handy, consid-ering that about 660 scans were taken in the two project phases in about 20 days.

Our equipment was used on the ground fl oor, in areas with poor lighting conditions, upside down and on the upper fl oors - even along the towers’ surfaces. This highlights the fl exibility and the various applications of Z+F equipment.

We’re very satisfi ed with the results and all project partners approved of our latest laser scanning tech-nology. This is also a great encouragement for us to continue developing innovative and state-of-the-art solutions.

It was great to be a part of the very special 3Dom project and we would like to thank all parties involved. The collaboration with Doug Pritchard of Heriot Watt Uni-versity as well as Chris Wick-enden with his associates and students of Fresenius University of Applied Sciences was a unique and out-standing experience.

Dr.-Ing. Christoph FröhlichCEOZoller + Fröhlich GmbH, Wangen im Allgäu

The project was a real challenge and scanning with our new Z+F IMAGER® 5010X - using no targets - a great opportunity to prove the “Blue Workfl ow”.

We appreciate the opportunity being part of 3Dom and are glad that everything worked out well for all project partners.

Coloured 3D point cloud of the Cathedral‘s main aislePicture: Heriot Watt University

Registered scan positions in Z+F LaserControl® ScoutPicture: Z+F