|
As well as carrying out traditional surveys with high tech instruments as above, we also have another technologically advanced weapon in our arsenal – A LASER SCANNER!
So what is a laser scanner…
If you have ever seen Star Trek or Star Wars… no, no, no, let's be serious!
Survey instruments as above use a laser for measuring work on the principle of sending out a beam of light (laser light) every time the button on the instrument is pressed. The laser beam of light then bounces off any given target such as a single point on a structure.
After bouncing off the given structure, the beam of light returns to the instrument and the time taken for the beam of light to reach and return from the fixed point on the structure is recorded. The time taken (time of flight) produces an accurate measurement from the fixed point to the instrument, whilst in turn the instrument calculates and records the angle of the instrument in both horizontal and vertical planes. The calculation of angle, time and therefore distance give a fixed measured point in time and space and this is utilised to provide survey data by way of a fixed measured point.
The difference with laser scanning; albeit whilst in principle using the same beam of light (laser light & time of flight) is that the instrument sends out thousands of beams of light per second to scan a structure with many fixed measured points forming what looks like a low resolution digital photograph made up of lots of points in a grid pattern; with each point being a fixed and measured point in time and space; the resulting image widely known throughout the industry as a pointcloud. The advantages of this type of survey is that many millions of survey points are captured, not only providing a low resolution image, but with each and every point of that image being a measured point; therefore capturing huge amounts of survey data beyond what you may even require, but allowing additional data to be extracted from the survey now and at a later date if required.
Although laser scanning has been around in its infancy for several years, early technology had its limitations in relation to distance and accuracy, whereby distance was limited in order to obtain a high level of accuracy or limited accuracy obtained in order to get good distance.
Due to technological advances, the latest high definition instruments have the ability to have both good distance and accuracy, making them viable for a wider range of uses and in particular for the surveying of buildings and structures. Although as with all instruments, laser scanners have their limitations, they are ideally suited to the capture and recording of data from complex structures especially with poor access. For example it would be possible to survey the intricate detail of say the ceiling of Wells Cathedral from ground level or Clifton Suspension Bridge from the bridge, the gorge below the bridge and surrounding topography. In fact a laser scanner can accurately survey almost any structure from an aeroplane to a naked woman (or man… after all we are an equal opportunity employer!)
Where traditional survey instruments in practice are able to practically capture limited amount of data from such structures, a high definition laser scanner can capture huge amounts of data all of which can be measured and positioned accurately to form accurate survey data and the resultant data transferred to a wide range of software.
The latest high definition laser scanners can also take digital photos and videos of the structure as they scan (photo or video dependant on instrument used).
This instrumentation is like Star Trek or Star Wars when the competition are usually more Phantom Of The Opera with a wooden leg!
|
