3D Scanning Glossary

A glossary of key terms frequently used within 3D scanning and reverse engineering processes.
  • 2D Drawing- In CAD we can create a two-dimensional view of a product or object, this object is perceived with reference to 2 axes, where a 3D model would be with reference to the 3rd ‘Z’ axes.
  • 3D Laser Scanning- Laser stands for Light Amplified by Stimulated Emission of Radiation. 3D scanning device that uses a laser to allow the scanner to determine and create coordinates. The laser scanner omits an intense single beam onto the surface of the object, unlike an optical scanner that projects a ‘volume of light’ projecting a ‘fringe pattern’ onto the surface of the object. Due to the intensity of the laser it is less susceptible to changes in ambient light conditions. There is a debate on which system, optical or laser have the greatest resolution / accuracy. Both systems have their own advantages, depending on multiple factors.
  • 3D Modelling- Is the use of CAD software to create the representation of a three-dimensional model of an object so it can be designed in a 3-dimensional space. Through the use of powerful CAD software, large 3D models can be generated to enhance and speed up the design process.
  • 3D Optical Scanning- This is where digitised scan data is obtained shot by shot, as a ‘fringe pattern’ of light which is projected and laid over the component being scanned. As a scan is completed the digitised point cloud data is modified, and the software determines the 3D coordinates by calculating the returned patterns of high accuracy divergence and convergence of the fringe pattern. This type of scanning can be used within a blue light scanner. PES Scanning uses equipment from the internationally-respected German measurement company GOM’s structured blue light 3D scanning system. GOM is the system of choice for the major OEMs including Rolls-Royce, Jaguar Land Rover and Boeing.
  • 3D Scanning- This is a process that involves measuring an item and capturing its data, using one of a number of systems including: 3D optical Scanning, CT Scanning and 3D Laser Scanning. This data forms a point cloud which is then imported into CAD. Note that the data imported into CAD is a ‘dumb data’ and cannot be used until it has been reformatted in CAD using specialist ‘bolt on’ software
  • As Scanned or As Built- This is the process of using the scan data without modification, therefore the PES Performance engineers will reverse engineer the part from the data and reproduce all the wear, distortions and defects as per the original scanned part. (This excludes and breakages or stress fractures etc).
  • Blue Light Scanning- In 3D optical scanning this refers to the colour of the light projected onto the surface of the object. Blue light scanners are less sensitive to heat and reflectivity than white light scanners, and so produce more accurate results. PES Scanning uses a blue light GOM system capturing 5 million data points per scan.
  • CAD- Stands for Computer Aided Design and is a type of software used to create precise models or technical illustrations. CAD has become the main tool of design engineers. There are varying CAD software packages on the market from basic entry to advanced packages. Both PES Performance and PES Scanning use the advanced CAD packages, Siemens NX Version 10 to 12, and Catia.
  • Colour Map Deviation Report- This is one of the reporting processes we use for our clients to highlight deviation of the scan data from the original CAD model or physical control part. The deviation or surfaces outside the specified tolerance band are highlighted using colour mapping to identify such deviations. This allows the client to quickly identify areas which are out of tolerance, from the inspection scan data. This approach is very easy to monitor for quality inspection purposes.
  • Competitor Bench-marking- This process is used by clients to review and carry out analysis of a competitor’s product. Competitors will not give their CAD models and data away for the product they have on the market. The only way it can be analysed or ‘Bench-marked’ and compared against the client’s own products will be through reverse engineering. This can include scanning all the components parts, importing the digitised data into CAD and then turning that data into a 3D model. Once the 3D models have been produced the parts can be tested and run through simulation software, i.e. FEA & Computational Fluid Dynamics (CFD) as a single component or as a complete, digitised assembly. It must be noted that to prevent infringement of intellectual property it is crucial that the data is only used for analysis.
  • Cross Section Analysis Report- Compares cross sections of CAD model data against the original designs and can be used for the verification of part thickness as selected and or to inspect the geometry.
  • CT Scanning- Stands for computed tomography and is a non-destructive process which uses x-ray equipment to inspect the internal and external features of a component and produce 3D representations of the component. This is a very powerful tool for inspecting internal components without destroying the part being inspected. It has limitations based on material thickness and type.
  • Design Intent- As opposed to ‘As scanned’ the PES Engineers would use the scan data as a guide, reverse engineer and reproduce the part as we believe it was originally designed; the design intent. This process could include repairing any worn or broken sections, truing up bores and creating flat planes to name a few.
  • Design Optimisation- This is to achieve the “best” design relative to a set of prioritised criteria or constraints set by the client or design engineer. Engineers are often required to identify a few appropriate design solutions and then decide which one best meets the need of the client. This decision-making process is known as optimisation. For the scanning and reverse engineering of legacy parts, our engineers, use the data to reproduce the part ‘as design intent’. However, they could then look to make improvements to the design and function not available to the original designers, as the technology either did not exist at the time or was not cost effect. Optimisation could include manufacturing the part in lighter, stronger materials, changing bearings to reduce friction, wear and heat and improve lubrication through design. The options are varied.
  • Digital Archiving– This is the use of data capture technology to create a digitised copy of a part or object. The data is stored in a digital archive and used as and when required. PES Scanning use it for multiple applications. One main area in engineering is during a client’s Planned Preventative Maintenance period. PPM is used to define a period of maintenance for critical machinery, so the client can limit production down-time. With large legacy equipment where spares are limited, expensive or no longer available, the components can be scanned, and the digital data archived to be used when required. E.g. The last critical part has been used to repair the machinery and if it fails there will be a long and costly lead time to make a replacement. However, if there is already a digital database the part can now be reverse engineered and manufactured to reduce the risk and cost of a failure. Archiving is also used to create a digital file of priceless items either for insurance purposes, identification, repair or making a reproduction for display therefore protecting the original piece. It can typically be used in the high-end classic car market when a car is damaged. The car can be brought back to its original condition using the archived data. Simply data archive allows our clients to have back up data to ensure if anything happened to the item, there is digital data available to fall back on if you needed to identify, repair or reproduce the item.
  • Dimensional Inspection – the acquisition of measurement data (usually 2D or 3D) of an object. Then those dimensional inspection results are typically compared to drawing specifications or CAD models to check whether the measured object is within/outside specified tolerance
  • Dumb Data- There is an assumption that scan data, or the mesh can be manipulated from the raw data. This is not the case as it needs to be imported into a suitable CAD software to transform it into a working geometry. This process can take hours or for more complex geometry, days. Therefore, the data is known as ‘Dumb data’.
  • First Article Inspection (FAI) –  This is a formal method of providing a reported measurement for a given manufacturing process. FAI consists of comparing inspection results of an initial sample item against given specifications, such as a drawing, CAD model or certified sample. Despite the name, the inspected item may not be the ‘first’ produced, but rather a random sample of parts from the first production batch.
  • Geometric Dimensioning & Tolerance (GD&T)– It is a system or process of symbols, rules and definitions used to define the geometry of mechanical parts. It is one of the most powerful tools available that can improve quality, reduce cost and shorten delivery time. It is an international language used on drawings and models to accurately describe a part. The language consists of a well-defined set of symbols, rules, definitions, and conventions to describe the size, form, orientation, and location tolerances of part features.
  • Initial Sampling Inspection Report (ISIR) – ISIR provides a systematic overview of sample parts, which require evaluation before large scale production. Inspection tests include; dimensions, functions, materials, reliability, attributes and a visual inspection.
  • Laser Scanning –  (see 3D Laser Scanning)
  • Legacy Part- There are still machines and parts operating today that, whilst still very effective are becoming difficult to maintain due to shortage of spare parts or no spares at all. 3D scanning, through reverse engineering can help to reduce the costs and eliminate the risks through Planned Preventative Maintenance.  A legacy part is any part or equipment that was not designed in the digital age and has no or limited drawing available. This can be from a 100-year-old 1000-ton press or large 100-ton gearbox to a complete classic car or aircraft. Through 3D optical scanning we can scan the parts or even a worn broken part, import the data into CAD and through reverse engineering produce a new part, either with the wear built in, or as a completely new part. A brand-new ‘worn’ part can be designed to interface and fit this existing component in the system. The parts can be produced ‘as scanned or commonly known ‘as built’ to ‘design intent or the part could be completely optimised.
  • Line of Sight- Excluding CT scanning, 3D scanning systems can only capture ‘line of sight’ data. It is a literal term as the scanners can only capture surface data that you can see. Line of sight is also dependent on how the scanning head can be positioned to capture the data. For example; a bracket where the inside face is close to another feature it may not be possible to capture all the data.
  • Metrology – This is the science of measurement and its application. When referred to in engineering metrology  means the process of measuring the properties of individual objects; dimensions, weight, etc.
  • Optical Measurement –  This refers to noncontact measurement using various light sources. It usually requires at least one lens, a light source and a detector. It differs from other forms of inspection, such as tactile measurements (like touch probes).
  • Optical Scanning – (see 3D Optical Scanning)
  • Photogrammetry- This is a technique of taking measurements from photographs. A camera is positioned close to the subject and is typically hand-held or on a tripod. The output of photogrammetry is a 3D model of a real-world object.
  • Planned Preventative Maintenance (PPM)- This is about minimising the risk of lost production time if crucial equipment fails. If a company has a scheduled maintenance period then this is the best time to undertake 3D scanning of key components, parts and equipment to produce a digital archive. The digital archives provides the point cloud data needed to produce spare parts or replacement parts, and at the same time reducing the down-time to minimise impact on production.
  • Point Cloud Data- Is a set of data points in space which are generally produced by 3D scanners. For example our GOM 3D Optical Scanning system will produce up to 5 million data points of the object being scanned.
  • Polygon mesh- This is where a collection of edges and faces are made up to represent a polyhedral object in 3D computer graphics, either in our GOM inspect software or in our Siemens NX CAD software. The faces usually consist of triangles that make up this model.
  • Post Data Clean Up- If after scanning, the scan data or mesh is not watertight the data can then be imported into our GOM inspection software. The mesh is then filled manually by one of the PES design engineers. For a large complex part this could take a number of days.
  • Production Part Approval Process (PPAP) – This is used to establish confidence in suppliers and their production processes. Measurements are taken of the parts produced in order to ensure; the manufacturing and quality requirements of the parts supplied are met; there is evidence that the engineering design record and specification requirements have been fulfilled; and, it can be demonstrated that the manufacturing process can consistently produce parts to the quality required.
  • Quality Inspection Part- Through data capture processes such as 3D Optical Scanning, CT scanning and 3D Laser scanning we can undertake quality inspection by using the digitised data or large data set point cloud. This highly accurate data is used to compare a physical part against the original CAD models to ensure the manufactured part is ‘as designed’. The data can also be used to compare against original scan data of a part, inspecting changes or variances in tolerance (so called ‘tolerance creep’) during the manufacturing process. PES Scanning can generate a bespoke inspection report tailored to the requirement of the client and which can be used to refine the manufacturing process or archived for auditing purposes, such as in aerospace and medical sectors.
  • Quality Inspection Tooling- As with quality inspection, a brand-new tool can be scanned and inspected against the CAD model to ensure the tool is within the correct tolerance band before manufacture. This can ensure the tooling can be fine tuned before production starts. See also Tooling Trend Analysis and Inspection.
  • Reference Points or Un-coded markers- These round un-coded markers are geometrically accurate and are placed on the part to be scanned, or around the part onto a jig or fixture. They are used within 3D scanning to ensure high accuracy in the measurement. The markers come in a variety of sizes; which size you use will depend upon the volume and lenses selected on the scanners, factors which are dictated by the size of the part and the resolution required. By using un-coded markers, the part and the scanner can be moved, once the first scan has taken place. This is a key feature of our GOM Optical scanning systems.
  • Reverse Engineering- This is the process of collecting data from an item, component, or piece of equipment, through analysing its function and structure. For example, if there is no original documentation of the item available we can use reverse engineering to produce CAD models for several purposes. i.e. analysis, reproduction or replacement parts, or design optimisation.
  • Siemens NX- This is an advanced CAD software package used by the PES Performance team. We are currently working on version 10 to 12, but also use CATIA. The software includes additional features allowing the team to import .stl file format from the scanner.
  • Small and Large Batch Bureau Service- This is where we can 3D scan large or small numbers of parts, for quality inspection or reverse engineering in our scanning workshop facility. In the case of large quantities, we can design and manufacture or 3D print jigs that will help to secure the part. This can save time and money for the client and be a more efficient method, rather than placing coded markers on each part.
  • .Stl file Format- This is an acronym for a variety of terms e.g. ‘stereolithography’, ‘standard tessellation language’ and ‘standard triangle language’. It is a type of file format which has a triangular representation of a 3D object and the surface of the object is made up of a series of connected triangles. It is widely used for rapid prototyping, 3D printing and computer-aided manufacturing. Not all CAD software packages have the capability of reading. stl formats and in most cases require the user to purchase a ‘bolt on’ package. More CNC machining software are now able to manufacture a part directly from. stl format scan data, removing the requirement for a manufacturing drawing. (This approach can only be used in certain circumstances).
  • Tooling Trend Analysis and inspection- This is the process of measuring a piece of tooling or fixture to understand the point at which it moved outside of an acceptable tolerance band for the part being produced. The process is to first scan the part and inspect against the original CAD model then at regular intervals carry out further inspection and measurements to monitor changes in shape and form during the life of the tools. The information can be used to build up analysis of how the tool performs over time. The data can also be used to compare against other tooling performance in the same family. Using this data our PES Performance engineers can help clients to improve and optimise the process, maintain quality, reduce wastage and improve margins.
  • Water-tight Scan- A water-tight scan or mesh is where a scan can capture all the surface data. If there are line of sight challenges some data may be omitted, leaving gaps in the mesh. In these cases the scan would not be completely ‘water-tight’ and would therefore require some post-data clean up work to replace the missing scan data.

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