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technical & practice - Digital techniques and materials advances are offering faster and more accurate measurement and production methods

Once upon a time, if architects wanted to assess the deterioration of a building's exterior, they needed a shooting stick, a pair of binoculars, sunscreen and a lot of patience. They literally drew the cracks and shaded the areas of deterioration on their clipboards.

Back at the office, they then had to enter their findings into CAD.

Now, 'with a high-quality, very detailed photo, it's no longer diagrammatic, it's the real deal', says architect Steve Krause of QPK Design in Syracuse, New York. 'You can see which mortar joints are cracked with a lot less effort. This technology lets us photograph, as opposed to draw, the exterior of buildings.' The technology - large-format digital photography - is one of two being applied to help architects capture and manipulate images of a building's structure and surface. New York photographer Tom Watson and his partner Rob Howard take largeformat digital photos using a BetterLight scanback attached to an ordinary 4 x 5 view camera and a laptop.

The BetterLight gathers the information for an image in a continuous scan, capturing light one row of pixels at a time and recording all three colours equally to achieve true RGB (red, green, blue representation). Capturing a single file of more than 144 megapixels can take several minutes.

Ben Levine of King & King Architects in Manlius, New York, deployed Watson and Howard's large-format digital photography on a project that involved repairing damaged stonework on the M&T Bank building.

King & King had designed cornice flashing replacements.

'We needed building elevations to scale so that the work needing to be done could be marked up and detailed and so the contractor could take off the extent of repairs and new materials to be applied, ' says Levine.

To do this conventionally on the 10-storey building was impossible due to its sheer size. Measuring and drawing the building and then entering it in CAD would have required a massive expenditure of time and manpower.

So Levine enlisted Howard and Watson. 'While Tom's services at first seemed to be relatively expensive, this approach saved a lot of money and quickly provided information that could be obtained no other way.' 'Unlike smaller digital photos, the large-format images can be enlarged to lifesize and beyond on the desktop without degrading into pixels. This provides very accurate information and documentation of existing conditions, allowing for a preliminary inspection from the office, ' Levine says. No more hanging about on site, inspecting the building with binoculars.

And, as Watson said in a recent interview, architects can load his photos into an AutoCAD programme for condition surveys. Files of this size, loaded into CAD, can be scaled and have enough reserve sharpness to pinpoint individual cracks. 'For technical uses, there is no doubt in my mind that film is dead, ' says Levine.

Krause has encouraged Watson and Howard to invest in another facet of this technology: large-format panoramic photos. 'Traditionally, it's very difficult to get good-quality imagery of building interiors because, in all but the largest interior spaces, it's impossible to get far enough away - so you seldom get an idea of what the space is like, ' he explains.

Howard and Watson use a BetterLight Pano/WideView adapter - a motor that slowly turns the camera through 360-. They can take 1GB-plus images up to 8,000 pixels in height.

'The camera travels through an arc on a tripod, taking thousands of tiny incremental photos, little slivers that meld together into one apparently seamless image, ' says Krause. 'With this technology you can get a great image of a hotel room.' 'Plus, ' he adds, 'you can get wideangle views of completed projects with a 'wow factor' - they capture the interest and imagination. All of our most recent high-profile projects were photographed this way.'

Krause also favours another imaging technology: laser scanning that captures details of every surface on a building's interior or exterior, which can be converted to CAD representations of its existing condition.

Pittsburgh-based Quantapoint uses a laser scanner to collect, register and verify billions of rapid, but highly accurate, measurements to create 'as-built laser documentation' that architects can share across project teams as interactive, photorealistic 2D or 3D images.

'Traditionally we walk around with a tape measure and a clipboard, ' says Krause. 'This is being supplanted by these guys' ability to shoot a whole room. They put targets on the walls and number them, then the computer builds models and prepares floorplans. The accuracy is far better than with tape measures.' Quantapoint guarantees quarter-inch accuracy.

Quantapoint's as-built documentation provides accurate dimensional information for prefabrication and for clash detection, thus reducing costs and, says the company, reducing construction rework by more than 80 per cent. Architects can extract piping and instrumentation diagrams, isometric diagrams, piping sections and elevations - the list goes on.

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