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Dirk Dusharme @ Quality Digest

Metrology

3-D Scanning Helps Restore Russian Orthodox Church

New tools bring new life to 19th-century church in Czech Republic

Published: Thursday, January 5, 2012 - 17:11

One of the more fascinating applications for large-volume 3-D scanning is in preserving our past. Sure, for those of you who work in the manufacturing or building industry, 3-D scanning is all about the future, making sure your product is in spec and performs properly going forward. But for those who work in historical preservation, 3-D scanning has given architects and preservationists a mighty tool in their arsenal, one that allows them to preserve, reconstruct, or resurrect heritage sites.

Recently, 3-D laser scanning employing a FARO Focus3D laser scanner, Pointools software, and various traditional surveying equipment was used to reconstruct a Russian Orthodox church in the Czech Republic. High-resolution and highly accurate 3-D scans along with color image overlays are allowing artisans and architects to bring decorative elements of this amazing church back to life.

During the summer of 2011, BW Precision Systems (BWPS), specialists in land and engineering surveying, 3-D laser scanning, and digital photogrammetry, was contacted by Medika Projekt Karlovy Vary, an architectural design firm, to assist in a complete reconstruction of all decorations of the St. Peter and Paul Russian Orthodox church in Karlovy Vary, a spa city in the western Bohemia region of the Czech Republic. The church was built in the 19th century, partially funded by Russian immigrants who sought treatment in Karlovy Vary’s mineral springs. The church is lavishly decorated, including a relief representing Russian Tsar Peter the Great.

The church is 35 m long, 14 m wide with a 40-m tall bell tower. A central tower surrounded by four smaller towers is at the end of the nave. Each tower is topped with the familiar onion-shaped spires one sees in Russian Orthodox churches. Technical and educational facilities are located beneath the church. The church has been reconstructed several times, the last time during the 1980s.

To accomplish proper restoration of the decorative elements of the church, including several large murals, Medika needed precise 2-D and 3-D CAD drawings of the entire church and rectory, both inside and out. Medika contacted BWPS because of its experience with 3-D scanning and earlier historical preservation projects.

The completed CAD data supplied by BWPS would be used by Medika for several purposes. At earlier stages, the highly detailed elevation drawings would help designers understand the amount of repair work that needed to be done and to prepare a budget. Two-dimensional and 3-D CAD data would help in repairing all the decorations on the facades of the church, as well as improvements on the structure itself, such as insulation. Several murals also needed to be repaired. Three-dimensional scans with color image overlays would give contractors and artisans both dimensional and pictorial information.

At the start of the summer project, BWPS used total stations and other survey methods to coordinate scan positions and targets in order to establish a coordinate framework. The actual 3-D scanning was done with a FARO Focus3D scanner. According to Jiri Blazek, managing director of BWPS, the scanner was chosen because of its small size and light weight, making it easy to position when scanning interiors. It is also one of very few scanners that can scan directly overhead. According to Blazek, the project required 100 scan stations to cover all parts of interiors and exteriors. “Because of the height of the church, some of the scanning had to be carried out on roofs of surrounding buildings,” says Blazek. “We also scanned the rectory house situated next to the church, which added to the already huge dataset collected at the church.” The final 5 mm-grid point cloud consisted of 380 million points.


Scanning the St. Peter and Paul Russian Orthodox church from surrounding rooftops using FARO Focus3D laser scanner

All of the individual FARO scans were first aligned and combined using the software that comes with the FARO Focus3D laser scanner and then brought into Pointools software for manipulation, data extraction, and eventual export into 2-D and 3-D CAD files for use by Medika. Pointools enables project teams to reference and reuse point-cloud models with billions of points inside a broad range of applications. One of the strengths of this type of software for historical preservation is that designers can take a slice of the point cloud at any point and quickly create 2-D elevation drawings, something that would be impossible with other measurement methods.


Use of Pointools software allowed the creation of this longitudinal section through the church. The resolution of the point cloud in this particular application is 5 mm.

Although BWPS used the FARO scanner for all its scans, it could have easily used a mix of scanners, points out Joe Croser, vice president of products for Pointools. “You can use the strengths of different scanners to do different types of scans and then use Pointools to align the data,” he says. “I’ve been involved in survey projects where we’ve scanned the outside of a building using a RIEGL scanner because we wanted real long range, low noise, and high-accuracy scanning; and then we’ve gone inside the building and used the FARO scanner. Once you get back to the office you join the data and use it as if it is a single scan.”

Blazek and Croser point out that because the scan data are aligned with a coordinate framework established by the total stations, whose positions are precisely known, it is possible to return to the site in the future, reestablish the datums using total stations, and then capture more data, which can be easily aligned to the existing data.

“This project could have been done without laser scanning, but the effort would have been so much higher and you could never have gotten this much detail,” says Blazek. “You could employ photogrammetry for the elevations, but I still think laser scanning gives you more efficient results than other methods.” Blazek adds that it would have tripled the time on site and would not have provided the same detail.


Fly through of St. Peter and Paul Russian Orthodox church. Data captured by FARO Focus3D laser scanner and processed in Pointools software.

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Dirk Dusharme @ Quality Digest’s picture

Dirk Dusharme @ Quality Digest

Dirk Dusharme is Quality Digest’s editor in chief.