SHINE: The innovation that sets Hexagon’s 3D laser scanning solutions ahead

How does SHINE make laser scanning a more dependable metrology tool?

Over the past decade, technological improvements have seen 3D laser scanning become an increasingly important and viable alternative to tactile measurement across a wide range of inspection tasks. Modern high-performance 3D laser scanners can now acquire more than a million points in a second, covering an entire object instead of just a few key features and in much less time. The result: an easy-to-understand colour map that compares the acquired point cloud data against the design files.

A brief history of 3D laser scanning

The first generation of laser line scanners required the user to manually define and fix the optical exposure settings for the type or colour of material to be measured. For example, a car is grey, but it has some black areas. An early laser line scanner could either scan one or the other surface colour, but never both in one pass.

A second generation of scanners offered automatic exposure, meaning that for every scan line, the scanner would find the best settings automatically, according to the surface colour perceived by the scanner’s camera. However, in this case the entire scan line always needed to be on the same surface colour because every point on the scan line was measured at the same exposure setting. This was certainly an improvement, and with the right series of scanner orientations was a technology that could be helpful, but it was still not perfect.

In the next generation of scanning technology, Hexagon introduced the “flying-dot” scanning concept to the market. Scanners based on flying-dot technology could adjust the exposure setting on every single point along the laser line and therefore scan any material in any orientation. But this technique came with a drawback: the motorisation needed within the scanner to make this type of scanning possible also made it relatively slow.

Today, the laser line scanner market has evolved even further, especially with the introduction of dynamic exposure settings and automatic noise elimination, functions that have allowed great improvements in scanning usability and data quality. The current-generation Absolute Scanner and HP-L-10.10 laser scanner product ranges from Hexagon use a set of optical algorithms known as SHINE technology. This allows for 3D scanning on challenging materials such as chrome, shiny black or multi-colour surfaces with ease, as well as automatically filtering scan data outliers without compromising scanner performance and accuracy.

So far, there are four 3D laser scanners that boast integrated SHINE technology: the Absolute Scanner AS1 and Absolute Scanner AS1-XL, which offer high-definition feature and large surface scanning for Hexagon laser tracker and portable measuring arm systems; and the HP-L-10.10 and HP-L-10.10 Lite, the flagship and O entry-level laser scanners for stationary CMMs.

Here are some examples of real-world 3D scanning applications in modern industrial manufacturing that deal with challenging materials. Fundamentally, what these examples show is how often operators need to spend time finding the right exposure settings and laser intensity to use when scanning different surfaces.

Finding the right balance

With typical laser scanners, a measurement session would begin with the operator needing to choose appropriate settings for the part’s surface. Is the surface pale or dark? Is it shiny or matte? Is it rough or smooth? This complexity can cause different operators to interpret the scanner settings in different ways, causing variability in the scan data and introducing room for errors.
 
The table in Figure 1 shows the relationship between the part’s surface darkness and the scanner’s optical settings. As a surface becomes darker, the exposure time of the scanner’s camera (here shown as “Exp time”) must be increased to be more sensitive to incoming light, because a dark surface returns less laser light to the scanner’s sensor. The operator should therefore move the cursor to the right to a higher percentage value in order to scan the part correctly. However, this increase also raises the risk of spurious data — noise — appearing in the scan. This might result in a smooth part appearing rough in the scan, or give the scan an incorrect shape. Equally, if the settings are too low, there might be areas of missing information.
 
As you can see, it is often difficult to find the correct combination of settings that will allow the part to be measured in the most effective and accurate way possible.

Figure 1: Scanner settings adjustment options

 

What is SHINE?

SHINE stands for Systematic High Intelligence Noise Elimination.

It is a patented type of High Dynamic Range (HDR) technology that allows measurement of surfaces of different colours and levels of glossiness in a single scan pass. By using three different exposure levels for each measured scan line, all surface information is captured using the optimum settings at all times; one low-level exposure captures light or matte surfaces; a second high level exposure captures high-gloss and dark surfaces; and a medium-level exposure is used for other surface types.

Because SHINE ensures that the scanner is always operating in its optimum configuration, the range of surfaces that can be scanned is wider than with conventional scanners. Furthermore, this automatic adjustment to optimal exposure levels also allows for much cleaner data collection, avoiding the noise created when scanning at suboptimal exposure settings.

For the user, SHINE is a game changer, allowing them to simply pick up and user a scanner with very little training. Knowledge of the scanner settings described earlier in this document is not necessary, so parts can be scanned accurately without the variability caused by different interpretations of the settings. Operator A will obtain the same results as Operator B, regardless of their experience or skill level.

Another benefit of having fully automatic settings is improved reproducibility. When scanners had their exposure settings manually set, results between different users who used different settings — based on different personal preferences — were an issue. By using SHINE, different users will get the same result, making for a much more consistent metrology tool.

SHINE also saves time, as there is no need for running trials on the part before starting the measurement job. The SHINE algorithm could be compared to the best automatic camera settings ever developed; imagine a camera that can take photos in automatic mode better than a professional photographer — that is what SHINE offers.

The Absolute Scanner range and their positioners 

A laser scanner works by capturing 2D scan lines from the part surface. To provide a final 3D point-cloud to the user, this 2D information from the scanner must be combined with positional data that locates it in 3D space. This positional data comes from a ‘positioner’, which generally carries the scanner around the part. Examples of positioners include articulated arms, laser trackers and CMMs. The Absolute Scanner AS1 was the first scanner on the market that is compatible with multiple positioners, so that it can be swapped between laser tracker and portable measuring arm systems on the fly.

Laser trackers are portable systems able to accurately measure 3D points over large distances in any environment. Hexagon’s range of laser trackers are known as Absolute Tracker systems, named for the Absolute Encoders that ensure their high performance. They can be used to inspect parts from a size of just a few centimetres up to a those with a measurement volume of 160 metres in diameter. A laser tracker’s strength is on medium-to-large-sized objects like car bodies, railway bogies or coaches, aerospace frames and energy turbines.

The HP-L-10.10 laser scanner range 

For the HP-L-10.10 laser scanner range, the coordinate system is provided by a full stationary CMM. This includes Hexagon’s range of bridge CMMs for high-accuracy measurement, as well as horizontal arm and gantry CMMs for measurement of large parts.

Manufacturers employing ultra-high-accuracy CMMs have previously become accustomed to trading speed for that high level of accuracy when implementing 3D scanning solutions. Thanks to SHINE, the HP-L-10.10 range allows CMM scanning to offer similar repeatability and performance to tactile measurements carried out on the same measurement machine; the scanner is seven times faster than its predecessor while simultaneously delivering accuracy (probing form error) to within as little as 8 microns. 

Achieving this level of speed and precision along with excellent data quality and the ability to inspect a wide variety of surfaces and finishes within the same measurement sessions would simply be impossible without the advanced algorithms built into the SHINE platform.

What it all means for 3D scanning

SHINE is a powerful set of algorithms that have transformed the usability of 3D laser scanning. Embedding this technology in the Absolute Scanner AS1 and AS1-XL, as well as the HP-L-10.10 and HP-L-10.10 LITE, has created a range of scanners like no other on the market. Delivering fast, accurate results with minimal user input, our 3D laser scanners empower our customers to solve the challenges of virtually any application in manufacturing inspection.