Operating the Laser Scanners in Air

It is important to note that the scanners do not require any additional parts or modification to the hardware to switch between water and air scanning environments. The only difference is a calibration file the scanning software accesses prior to data collection. One calibration file is provided standard with the purchase or rental of the ULS-100 or ULS-500 and the pair of calibration files can be provided upon request.

Applications in Air and Water

The bennifit to haveing a single system capable of both in-air and in-water comes down to cost and convenience. Purchaing a single system is less expensive than purchasing a pair of systems and when operating in environments where both in-water and in-air scanning is needed deployment of the laser scanner is far simpler. The ruggedness of the 2G Robotics systems makes them ideal for a wide range of industrial applications when the scanners are to be mounted on robotic vehicles both above and below the water. Additionally, the cost to deploy suites of sensors into an enviornment can be expensive. By providing a single system that can perform both the in-air and in-water portions of the inspection the time required to perform the inspection and the number of deployments required can be reduced.

Example applications where these sensors may be used both in air an in the water is:
Sewer inspections, where part of the tunnel is flooded and part is dry.
Gas pipe inspection where compact and rugged inspection equipment is critical
Surge shaft inspections where the top portion of the shaft is dry and the bottom is below the water line.

Case Study

The 2G Robotics ULS-100 has been used for the inspection of welds and dents to gas pipeline. The ULS-100 was selected because of the rugged and compact construction of the sensor making it ideal for deployment on a tracked vehicle. Using the resulting scans the client was able to accurately assess the geometry of the scanned pipe sections. Using geometry information for welds and dents clients can ensure that maintanence funds are allowcated only where they are needed.

For additional information on Underwater Intervention visit :http://www.underwaterintervention.com/index.htm

Subsea Jacket Certification

Underwater inspection of these jackets includes the thorough examination of all areas where small or large flaws could occur. Subsea jacket inspection is an ongoing concern for the industry and regular recertification is required for their continued use. High detail visuals are required on key areas such as weld areas and other joint areas found all over the structures. These inspections are often carried out over longer periods during the recertification process. While the importance of such inspections is widely accepted, it is sometimes difficult to discern what the best methods for inspection are, but high detail and reliable information is a must.

The high demand for accuracy has led to technological breakthroughs in underwater imagery and measurement. Underwater laser scanning technology has stepped to the forefront with unrivaled accuracy. Able to capture data 100 times more detailed than sonar, units such as the ULS-100 and the new ULS-500 have created an opportunity for inspection companies to report measurements with confidence. In subsea jacket inspection these sensors can collect up to 250000 points per second with the data streaming real time to the standby vessel above. Laser scanning devices and sonar systems can all be easily deployed by a wide variety of ROV systems or a team of divers.

Subsea Jacket Defects

Possible applications for the 2G Robotics ULS Underwater Laser Scanners during subsea jacket inspection include:
- High detail weld inspection
- Diametrical readings of members
- Visuals in dark and hazardous areas
- Measuring any imperfections in the structure
- Ability to retrieve accurate data through moderate visibility

Intuitive Visualization

The data collecting by the ULS systems can be displayed and manipulated in many different software applications as well as being viewed in the scan viewer software supplied with the rental or purchase of the unit. Isolating higher priority areas within scans is easily done to further investigate specific areas of interest.

Finding, analyzing and maintaining problem areas will greatly extend the lives of these structures therefore increasing their value. Jacket structures are strong, reliable, and resilient; designed for purpose and are highly tolerant to many deformities and damage but none the less inspection and maintenance will continue to play a vital role in their future. Hopefully all inspection will be performed by high detail measurement systems in the future, ensuring a high level of quality when it comes to the safety of these important structures.

2G Robotics has expanded our line of underwater laser scanners with the development of the ULS-500. This longer range higher power underwater laser scanner is designed for scanning over larger areas reducing the number of setups required to obtain complete coverage.

ULS-500 Operation

2G Robotics line of underwater laser scanners uses light to capture measurements underwater rather than sound. By using light, a far more detailed and accurate understanding of your subsea asset can be obtained. Based on the same principles of operation as the ULS-100, the ULS-500 uses higher power lasers and is a physically larger system. 2G Robotics ALF technology (Ambient Light Filtering Technology) allows the system to operate in a wide range of environments. With a maximum data capture rate of more than 250,000 points per second, very fast scan speeds can be achieved.

Applications

The high power class 4 laser system is capable of scanning at 3 to 5m and will cut through and filter out a moderate level of silt in the water. The capabilities of the ULS-500 make it ideal to obtain underwater measurements with certainty. The system can be used for:

Offshore Oil Metrology

Pipeline Surveys

Bridge and Dam Inspection

Internal Large Tunnel Inspection

Ship Husbandry and Propeller Inspection

Underwater Archeology

CASE STUDY -

Parks Canada Takes Delivery of ULS-500

Underwater archeologists with Parks Canada have taken delivery of a ULS-500 Underwater Laser Scanner for high detailed inspection. Parks Canada is currently using the ULS-500 for the underwater inspection of a variety of historically significant shipwrecks. The ability of the system to inspect relatively large areas capturing crisp 3D models of the asset is beneficial to Parks Canada for preserving and documenting these wrecks. By comparing multiple scans over time, the underwater archeologists at Parks Canada will be able to assess the deterioration of these shipwrecks. Upon taking delivery of the system, Parks Canada personnel were trained at a testing site with a sunken plane fuselage. The ULS-500 was capable of capturing a very crisp 3D model of the fuselage section, clearly defining not only the shape and dimensions of the windows but also the rivet seams around the windows and between the panels of the plane fuselage.

This level of detail can be useful when assessing any subsea asset where details matter. Whether you are performing an underwater retrofit or wish to collect as built information as a baseline in the event of future damage, the ULS-500 is the most detailed underwater measurement system available.

Plane Fuselage Picture

Plane Fuselage 3D Scan

Scan Animation Video

Offshore Oil and Gas Construction

Underwater-Inspection-Offshore-Platform

Underwater Laser Scanner Deployed in Antarctica

Underwater Pipeline Inspection

Underwater Tunnel Inspection

click here to view a video presentation of this paper.

Turbidity (Silt)

Turbidity is a measure of the cloudiness of water: water with a high silt content (low visibility) has high turbidity. However, describing the behaviour of light as it passes through water is not easily described by a single turbidity value. As light is transmitted through the water it is scattered and absorbed by the particles. Both scattering and absorption reduce the total laser intensity reaching the target surface, and scattering has the added problem of creating false returns at locations other than the target surface itself.

Scattering occurs by the light reflecting in all directions off of the particles in the water. The size of the floating particles has an impact on the scattering characteristics of the light. With many smaller particles in the water the light will scatter relatively uniformly and the scatter pattern will be consistent over time. Fewer but larger particles will scatter light in a more variable manner.

Ultimately, the light transmission characteristics of an environment cannot only be characterized by the turbidity value of the water as size of particle and the makeup of the particles has an impact. For the purposes of demonstrating the performance of the ULS-100 in turbid conditions, a qualitative comparison between the scan quality and image quality is presented.

Results

To understand the impact of silt in the water on the scan quality a number of scans and corresponding pictures were taken with increasing levels of silt in the water. With increasing silt content in the water the quality of the scans degraded. At the point where there is nearly zero visibility in the water it is still possible to obtain some measurement data.