The Victorians gave us grandeur and detail, the Tudors, hips and valleys and the Plantagenets gave us crumbling castles. All of which we cherish as part of our Heritage but all unfortunately give us problems, and difficult ones at that!
Take the Founders Building at Royal Holloway (above left) in Egham, Surrey (William Crossland). A splendid example how the Victorians love to create finials, dormers, parapets and a myriad of roofs, all architecturally balanced and styled as was the fashion of the day. Little thought however, as how to maintain and monitor any future works a century or more later.
Equally, Little Moreton Hall in Cheshire (above right) , a building whose shape was based on the shape of the timbers available. Its quirky twisted look add to the complex array of small roofs that have been added over the centuries. Also if we look at any medieval castle we see the evidence of hundreds of years of weathering on the huge high walls designed to keep people out. All this and more has to be monitored and looked after by specialists whose job is to make sure that these buildings are preserved for future generations. It is a huge task and one that is expensive and fraught with a delicate balance of safety, method, and cost.
The UAV has now been firmly accepted as a survey tool, capable of reaching parts of buildings that would have either necessitated expensive access equipment or worse not being surveyed at all until a major project was undertaken and the building scaffolded. But photographs of a complex building are all well and good providing you know what they are looking at. Detail of a loose parapet on the Founders Building is very useful but which parapet? The UAV can most certainly cover all the structure with images and will have a huge capacity for highly detailed shots, sometimes hundreds, even thousands. All viewing sections of the structure clearly and making it fairly easy to identify areas of concern but little regard for the surveyor having to try to work out where they are looking and perhaps from what angle.
As a consequence of the demand for UAV technology increases so does the technology to use with UAVs. In particular is the ability to create a 3D point cloud from digital images. The video above is created from UAV and ground based digital images. There are a number of programs that will create a tessellated point cloud and build a 3D model, but these are no good to a surveyor. The reason is that the 3D model does not have enough detail and is subject to flaws in the model. What a surveyor needs is a model from which to view the actual digital photos. This model is referred to as a ‘ray cloud’, each point on the model is referenced from a number of images. By selecting a point on the model all those images that have that point in the image will be selected. You will see from the video that when the camera is ‘zoomed in’ the ‘points’ are clearly visible.The surveyor can then view the images and see the ‘point’ from whatever angle the image was taken from. The software can build the model to scale and thereby enable measurements to be taken from it, distance, area and volume. Also by using GPS the model can be positioned in ‘global’ space.
No matter how complex the structure may be or how difficult the architects of yesteryear tried to make the structure for on going maintenance and monitoring, the UAV has the tools to manage the task. I bet Wren, Jones, and Crossland never saw that one coming!