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How is a 3D Scan Performed?

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3D scanning a part, as you might imagine involves quite a few steps and an appreciation for the advanced technology that it is. A 3D scan is performed with care and knowledge of the part needing to be scanned and the purpose of the final data. 

The journey begins with understanding the purpose and characteristics of the part to be scanned. This foundational step is crucial, as it guides the entire scanning process, ensuring precision and efficiency. From discerning the part’s function to assessing its physical attributes, each decision is tailored to meet the unique needs of the project, whether for reverse engineering, quality inspection, or design optimisation.

Step 1: Part Review

Our process starts with a grasp of the data’s intended purpose, as this shapes the subsequent scanning stages and ensures a thorough yet cost-efficient scanning process.

This stage in the 3D scanning process is crucial as it involves understanding the specific purpose of the scanned data, which significantly influences the approach and methods employed in the subsequent stages of scanning.

Determining the Purpose

The initial step involves understanding the specific reasons for scanning the part. This could include reverse engineering, quality inspection, digital archiving or design optimisation.

The intended use of the scanned data dictates the level of detail, resolution and completeness of scan – there’s no point in scanning the whole assembly if we are only focused on one region for example.

Assessing the Part’s Characteristics

Factors like the part’s size, geometry, material composition, and surface characteristics are considered. This assessment helps in determining the most appropriate equipment and techniques. For instance, complex geometries or parts that require fixturing will need extra set up or clear glass-like surfaces will need spray.

The Scanning Strategy

Each part is different so a tailored scanning strategy is developed. This involves deciding on 3D scanner settings and parameters, understanding what needs to be captured and planning the scanning sequence.

If the part is large or has intricate details, it might require multiple scans from different angles.

Step 2: Setting Up

Whether we’re in our scanning studio or on-site, we execute the set-up portion of our strategy to scan in order to capture the necessary geometry. After that, we scatter scanning markers or reference objects randomly to ensure the 3D scanner knows where it is in 3D space.

Differences in Location

The decision to scan in a controlled environment like a studio or at an on-site location depends on the object’s size, mobility, and the specific requirements of the project.

On-site scanning offers the advantage of capturing the object in its operational context, which can be crucial for certain applications.

Scanning at our studio is often the choice for smaller parts that can be sent via courier and won’t incur travel costs and are generally cheaper being billed on a part-by-part basis rather than a half/day rate.

Targets and Fixtures

As all our equipment can be packed up and brought on site, this step is very much the same whether on-site or in-house. The parts are target up with reference markers that tell the 3D scanner where it is in 3D space. These markers are placed randomly but strategically on or around the object. As the scanner captures the object, it uses these markers to orient itself and accurately plot the object’s geometry.

Fixtures are used to mainly support the part and hold it securely at certain angles that have been pre-determined in our scanning strategy. Fixtures can also be used to simulate how a part needs to be measured based on it’s end-use. If a part is a component of a larger assembly, the fixture can replicate this and arrest the soon- to-be 3D scanned part as it would be in the assembly thus being a reliable way to measure a part.

Scanner Calibration

Before starting the actual scan, the scanner is calibrated. Calibration is essential to ensure the accuracy of the data captured. It involves aligning the scanner’s sensors and software to the known dimensions and geometry of the calibration plate or reference objects.

Test Scan

In some cases, test scans might be conducted to verify the setup’s effectiveness. This step helps identify any potential issues before the full scanning process begins.

Step 3: 3D Scanning The Object or Assembly

We cover every part of the object that requires data collection, just like digitally spraying paint on it. This data is then sent to our computer as a point cloud for further processing.

Beginning the Scan

Once the setup is complete, the scanning process begins. The scanner is methodically moved around the object, ensuring all surfaces are covered. This process can be likened to digitally spraying paint over the object, ensuring no area is left un-scanned.

Data Collection

As the scanner moves over the object, it emits a laser which reflects off the object’s surface. The scanner’s sensors capture this reflected light, translating it into digital data. This process happens rapidly, with the scanner capturing millions of data points per second.

Creation of Point Cloud Data

The collected data forms a point cloud, which is a set of data points in three-dimensional space. Each point represents a tiny portion of the object’s surface, and together, these points create a detailed digital representation of the object. From this a mesh can be created or we can go back in to re-scan any areas that need special attention.

Initial Review and Quality Check

Once the initial scanning is complete, a quick review of the point cloud data is often conducted to ensure all necessary areas are captured and the data quality meets the required standards. If gaps or insufficiently captured areas are identified, additional scanning may be performed to fill in these gaps.

Workspace and Part Clean up

Once we’re happy with the data collected it’s time to clean up the working area and remove and 3D scanning target that we used to capture the data.

Step 4: Post Processing

The post-processing stage of the 3D scanning process is where the raw data collected during the scanning stage is refined and prepared for its intended use. This stage involves several key steps.

It’s worth mentioning that depending on the end-use for this data it may not to desirable to refine the mesh.

Cleaning up noise is about as much processing NDT or quality control applications require and hole filling or surface re-meshing may alter the geometry of the scan away from the real part.

Cleaning the Data

Once the mesh is created, it often contains imperfections or unnecessary information. These can include scanning artefacts, noise, or data from background surfaces that were inadvertently captured.

The cleaning process involves removing these inaccuracies to ensure that the mesh accurately represents only the object that was scanned.

Refining and Optimising the Mesh

This step involves further refining the mesh for quality and usability. This can include filling in holes, smoothing rough areas, and correcting any distortions that may have occurred during the scanning process from target artefacts.

The aim is to create a clean, accurate, and high-quality digital representation of the object.

Output Format Decision

Depending on the project requirements, the final mesh can be saved in various formats such as STL, OBJ, or PLY. These formats are compatible with a range of applications, including CAD software, 3D printing, and more.

Supplying Clean Mesh Data

At this point, if the project requirement is simply to provide a 3D representation of the scanned object, the clean mesh data can be supplied to the client for their use in analysis, inspection, or as a digital archive.

Proceeding to Reverse Engineering (if required)

If the end goal is to create a CAD model or to reverse engineer the scanned object, the post-processed mesh serves as the foundation for this next stage.

In reverse engineering, the mesh is used to recreate the object in a CAD environment, allowing for modifications, enhancements, or understanding the object’s design and functionality.

Wrapping up

The 3D scanning process is a carefully planned and well-executed procedure, tailored to each project’s unique requirements. It begins with a thorough understanding of the part’s purpose and characteristics, guiding the choice of scanning methods and equipment used.

The process involves precise setup, accurate data capture, and expert post-processing to ensure high-quality results. Whether for reverse engineering, quality inspection, or design optimisation, the attention to detail at each step ensures the scanned data is both precise and valuable for the intended application.

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