Digitizing for the Purpose of Conservation
Historic architecture is being digitized and modelled for the purpose of conservation, preservation and protection of the structures and their cultural heritage. In the past, photogrammetical documentations were possible only with analog cameras of 5’x7’ or 4’x5’ frame size and accomplished by using a lift that was positioned and driven around the object and carried the photographer around.
Today, with the development of smaller and lighter aerial platforms (UAVs and cameras), surveying complex structures in populated environment is becoming easier, faster, affordable and more efficient, and the images are utilized for inspection, monitoring, 2D/3D image rectification and dense point cloud creation.
CopterSystems GmbH is developing intelligent aerial platforms and manufacturing tailor made UAV solutions for diverse applications.
Fokus GmbH Leipzig, is an engineering company that provides special services in the fields of architecture photogrammetry and focuses on complex surveying supporting the documentation of monuments, as well as photogrammetrical evaluation of historic photographs for dimensionally reconstruction of historic objects.
CopterSystems and Fokus GmbH Leipzig joined forces and executed a complex aerial survey for documenting the historic neo-Gothic church St. Mauritius in Frankfurt /Main. The church that was built in 1901 is located in a populated area and attracts many visitors. The challenge was not only documenting the structure, but also allowing the traffic of people around it uninterrupted.
2D Image Rectification
The four facades of the church tower – 42 meters high – were documented by 2D rectified images in the scale 1:20 and 300 dpi resolution. This corresponds to a pixel resolution of 1.7 mm at the object.
The decision to use 2D image rectification (instead of 3D ortho projection) was due to higher image quality of depiction of damages at the natural stone. The image rectification and image mosaic were made with metigo® MAP. Colour correction and final processing was done with Adobe Photoshop.
The metigo® MAP software has been developed by Fokus GmbH Leipzig in close cooperation with conservators since 2000 and offers image rectification and mapping, as well as quantity survey and analysis. On base of the true-to-scale image plans planer and conservators can document damages and estimate quantities that enables providing accurate cost and time estimations for conservation projects.
CopterSystems: Documenting Historic Buildings by creating true to scale image plans with Phase One 50MP camera, a UAV and metigo®
With Phase One Industrial’s lightest 50MP camera, surveillance of structures in populated areas is easier, faster and more affordable.
“The 50MP camera was integrated into the CS-P.O.C easily, and its high dynamic range enabled the capture of images in the highest resolution. The camera delivered excellent results with high level of accuracy and details that enabled our customer to use the true-to-scale image plans for the damage mapping and for the controlling process of restoration”
Roman PaulusFounder and CEO, Copter Systems
As with any project where buildings are occupied, the principal consideration is disruption to the daily routine and attempts to minimize it. In this specific project, the challenges were clear; the need to fly in the center of a big german city that is located close to the airport, and execute a surveying project close to a church – a local historical attraction with high density of visitors.
CopterSystems chose to integrate Phase One’s 50MP camera – the smallest and lightest digital medium format aerial camera, with CMOS sensor, quality capture from ISO 100 to 6400, 8280 pixels in cross track coverage, capture rate of 0.8 sec/frame, direct connectivity with FMS, GPS/IMU and Schneider-Kreuznach central shutter lenses up to 1/1600 sec.
Gisbert Sacher, Fokus GmbH Leipzig CEO said: “The usage of the UAV was a great help for recording images of the church in high quality. The usage of a larger lift was not possible and image recording would have taken more time.”