Scaling new heights with digital imaging
It takes a brave soul to climb ladders and photograph artwork 15 metres above ground. Which is why conservators and restorers of heritage sites may soon come to rely on a unique European digital imaging system perched on a robotic platform.
This innovative platform is the fruit of Vitra, an IST project that built on previous European research into digital photography and colour image processing. “The earlier research looked at architectural surveys and conservation assessment in heritage buildings,” says Lindsay MacDonald, coordinator of Vitra.
Conservation work, he notes, is typically based on the use of high-quality photos. But operating safely and efficiently at height is a problem for photographers of culturally valuable works and buildings. High tripods and ladders can be employed for heights up to 10 metres. Beyond that, scaffold towers are the commonest solution, but their erection requires much time and effort.
“Our project eliminated scaffolding,” says MacDonald. “We designed a robotic carrier to position the camera to sub-millimetre accuracy, with six degrees of freedom, at heights of up to 15 metres above floor level.” This enables photography of everything from parish-church windows to cathedral walkways.
The robotic platform has a pneumatic telescopic mast, which carries the camera and artificial lighting. Standing at the bottom, the human operators can control all of the acquisition system remotely with a man-machine interface. They can steer the camera, zoom in and out, control other settings, and preview the scene being captured by the camera.
The interface provides real-time information on the whole system’s status. It also generates data on the camera’s position in the building, aiding image archivists and those who may later carry out conservation work.
Also unique to this project is the new digital back that attaches to a Rollei medium-format camera body. It features a 4K by 4K CCD (charge-coupled device) sensor for high-quality imaging and an electronic interface for full remote control over all camera functions. “This back, demonstrated at the 2004 Photokina exhibition, is now being offered to original equipment manufacturers,” says MacDonald.
New software algorithms, also developed under Vitra, enable any image captured by the system to be handled in innovative ways. For example, colours within images can be characterised with reference to standard colours, allowing faithful reproduction of mosaics or stained-glass windows.
Other algorithms enable the stitching together of multiple images or the removal of unwanted shadows from photos of stained-glass windows. The stitching tool will soon be sold as a plug-in for the well-known Vasari Image Processing Software. Lastly, the project came up with enhancements to its image database and a new viewer for panoramic images, based on Java-3D and JPEG2000 software.
“Our system took hundreds of images during trials at five evaluation sites, four in Germany and at a World Heritage Site church in England,” says Vitra’s coordinator. “Results indicate that our captured images are of real worth to those who care for and restore such sites.”
The prototype system, he acknowledges, is heavier and bulkier than initially planned. But he believes that a re-engineered version would be perfect for heritage institutions doing survey and documentation work at height.
- Contact Information
- Lindsay W. MacDonald
- Professor of Digital Media
- London College of Communication
- Contact via E-mail
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