Whatever the reason, records kept during the initial construction phase are usually outdated. Refits planned using this data can lead to alterations while the rework is underway, causing delays and increased costs.
Laser scanners are the answer. A typical scanner, such as the Laser Scanner LS from Faro Technologies, is small enough to be flown out to an offshore oil rig by helicopter. At a capture rate of 120,000 points per second, it produces a 360¡ horizontal and 320¡ vertical of 27 million points after only seven minutes.
This cloud of data points generates a virtual 3D photograph in black and white, or in colour. Many scans can be registered together to give a representation of the entire facility, which can be walked through virtually.
Faro’s LS emits an infrared beam into the centre of a rotating mirror. The mirror deflects the laser around the environment being scanned. The laser scanner captures the reflected beam and measures the ‘phase shift’ of the infrared light. The difference in the laser phases allows the on board PC to calculate the distance of the laser from the object. When combined with two encoder readings measuring horizontal and vertical rotation, the x, y, and z co-ordinates of the reflection can be measured.
The addition of recently improved ‘colour option’ software enables scans to be coloured with almost zero parallax error, adding another dimension to the realism of the images. It is particularly useful where pipe colours indicate what they contain.
Once captured, the laser scan is shown on a PDA or laptop inside Faro Scene software, showing all the captured information. Settings for the scan resolution and speed can be altered, and with the click of one button the scanner can proceed with the next scan.
The software creates order and intelligence in the data, and gives planners, engineers and surveyors easier access to the required information.