Scanning large castings often involves oversized workpieces, subtle surface geometry, difficult multi-view alignment, and large point-cloud datasets. The challenge is to improve scanning efficiency while maintaining data completeness and stable alignment.

When using the 3DeVOK MT Gen2 3D scanner for large castings, choose a scanning mode suited to the workpiece and plan marker placement and resolution carefully. This article draws on practical experience to share three techniques: blue-laser marker-based alignment, infrared structured light + Markers First alignment, and a sensible point spacing of 0.5–0.7 mm. Together, they help streamline scanning and post-processing while maintaining data quality.

1. Why Are Large Castings More Difficult to Scan? Three Key Challenges

Large Workpieces Require Many Alignments

Large castings are typically 1–2 m or more and may require dozens or even hundreds of view alignments, significantly increasing the risk of cumulative error.

Weak Surface Features Can Affect Positioning

Cast surfaces are rough and often geometrically repetitive. Relying on geometry alone can cause incorrect alignment, layered data, or loss of tracking, directly reducing scanning efficiency.

Large Datasets Take Time to Capture and Process

Castings have a large surface area and volume. High resolution can make the point cloud grow rapidly, causing scanning delays and lengthy post-processing; a full day may not be enough to scan more than a few parts.

2. Tip 1: Blue-Laser Marker-Based Alignment (Recommended First)

For large castings, blue-laser marker-based alignment is a strong option to consider, especially when stable positioning is important, surface geometry is limited, or the scan area is large.

Live point cloud in the scanning software

2.1 How to Place Markers Correctly

• Spacing: For large castings, start with markers about 6–8 cm apart, then adjust to the part shape, scanning distance, and scanner recognition requirements.
• Use an irregular layout: Avoid arranging markers in overly regular or repeated patterns.
• Avoid prominent features: Where possible, do not place markers over pronounced features, as this can interfere with filling the areas beneath them later.

2.2 How to Maintain Alignment Quality During Scanning

Maintain enough common markers. Aim to keep at least 4 common markers visible in every scan frame.

Ensure sufficient marker overlap between adjacent scan areas. Pay attention to marker continuity between neighboring areas to improve alignment stability.

Keep scan areas continuous. Place markers in a way that provides a continuous path through adjacent scan areas and avoids gaps in marker coverage.

With the 3DeVOK MT Gen2 3D casting 3D scanner in 34-line blue cross-laser and marker-based alignment mode, the frame rate can reach up to 80 fps. A higher frame rate can improve data acquisition efficiency during continuous scanning; actual performance depends on the scanning environment, operating technique, and workpiece surface.

2.3 Three Advantages of Blue-Laser Marker-Based Alignment

3. Tip 2: Infrared Structured Light + Markers First for Faster Large-Part Scanning

In addition to blue-laser marker-based alignment, the 3DeVOK MT Gen2 can use an infrared structured-light source with Markers First alignment to improve efficiency when scanning broad areas of a large casting.

This combination is particularly suitable when you need to cover a large surface quickly, the geometry is relatively simple, and you want to reduce the number of markers to place.

3.1 How to Configure the Mode in 3DeVOK Studio

In 3DeVOK Studio scanning software, add a custom mode and configure the scanning method as follows:

1. Open the scanning mode settings and add a custom mode.
2. Select infrared structured light as the light source.
3. Set the alignment method to “Markers First.”
4. Confirm the settings, start scanning as prompted by the software, and monitor the tracking status in real time.

Adding a custom mode in 3DeVOK Studio: infrared structured-light source + Markers First alignment

3.2 Why Infrared Structured Light + Markers First Works Well for Large Castings

Infrared structured light covers a wider field, so each frame captures a larger area. This enables faster, more efficient scanning and is particularly suitable for sweeping across the broad surfaces of large castings.

Far fewer markers are needed. In pure marker mode, a frame needs to recognize 4 markers to align. In Markers First mode, a frame needs only 1 marker. This can reduce marker placement substantially and save considerable setup time. Note that although normal alignment needs only 1 marker, at least 2 markers must be recognized to restore positioning if tracking is lost. Keep markers distributed continuously and avoid long marker-free sections.

More stable alignment with less dependence on surface features. In Markers First mode, the software uses “geometry + markers” for alignment but prioritizes markers for positioning. This is useful for castings with few distinctive edges, holes, or curved features. By anchoring positioning with markers and using geometry as a supplement, the mode helps scan such workpieces steadily and efficiently.

Re-acquisition requires one additional marker. Although a frame can align normally with just 1 marker in Markers First mode, at least 2 markers must be recognized to restore positioning if tracking is lost. Keep marker distribution continuous and avoid crossing long marker-free sections to reduce repeated re-acquisition failures and interruptions.

3.3 How to Choose Between the Two Modes

The two modes can be combined in practice: use blue-laser marker-based alignment in critical areas where accuracy matters, and infrared structured light + Markers First across broad areas to improve efficiency.

4. Tip 3: Set 3D Scanning Resolution Sensibly (0.5–0.7 mm)

“Higher resolution means better data” is a common misconception. In practice, choose resolution according to how the data will be used. A suitable setting improves efficiency and avoids the cost of using unnecessarily high resolution.

4.1 Recommended Resolution for Large Castings

A point spacing of around 0.5–0.7 mm is generally sufficient for the main features of a large casting, including its outer contour, parting surfaces, and stiffening ribs.

4.2 Why Not Use High Resolution Throughout the Scan?

Larger datasets: Each frame takes longer to process, which can cause stuttering and dropped frames.

Higher hardware load: Computer resources are strained, and opening files in post-processing software may take a long time.

Lower scanning efficiency: Files can grow to several gigabytes, making transfer, archiving, and inspection comparisons more demanding.

Longer processing time: Total scanning time can multiply, cutting the amount of work completed in a day.

4.3 Recommended Workflow: Overall Scan + Local Fine Scan

The goal of 3D scanning is to capture complete, usable 3D data efficiently, not to maximize point-cloud density.

For large castings scanned primarily for contour inspection or reverse engineering, medium-to-low resolution with stable alignment can reduce scanning time by more than 50% while providing data quality suitable for downstream use. Switch to a local high-resolution fine scan for specific critical areas, such as mating surfaces that need close inspection, instead of using high resolution across the entire part.

5. Additional Practical Advice

Scan the main surfaces first, then the details. Build an overall framework before filling in deep holes, grooves, corners, and blind spots. The MT Gen2’s single-line blue laser mode is effective for capturing deep holes and blind spots; switch to it for deep cavities.

Move at a steady pace. Maintain a suitable scanning distance and ensure that each frame captures enough common markers. Moving too quickly can reduce data quality.

Consider a developer spray for highly reflective surfaces. The MT Gen2 handles black and reflective materials well, so ordinary castings generally do not need powder. If a highly reflective casting produces noticeable noise or stray points, first increase laser brightness. If the result is still unsatisfactory, apply a developer spray to reduce glare, then place markers and scan.

Path overlap: Around 30% is generally sufficient to maintain continuous alignment without wasting time.

6. 3DeVOK MT Gen2 Key Specifications

The 3DeVOK MT Gen2 supports multiple light sources and scanning modes. Choose according to workpiece size, surface condition, and scanning requirements.

Frequently Asked Questions

Q1: What equipment should I use to scan large castings?

A: Choose an industrial 3D scanner with a large scan field (≥ 1000 mm), a high frame rate for marker-based alignment (≥ 60 fps), and good adaptability to dark, reflective materials. For example, the 3DeVOK MT Gen2 has a scan field of 1100 × 1000 mm and supports marker-based alignment at up to 80 fps.

Q2: What is a suitable spacing for blue-laser markers?

A: For large castings, place markers irregularly about 6–8 cm apart and avoid prominent features. In pure marker mode, keep at least 4 common markers visible per frame. In Markers First mode, each frame needs only 1 marker.

Q3: How do I set up infrared structured light + Markers First mode?

A: In 3DeVOK Studio, add a custom mode, select infrared structured light as the light source, and set the alignment method to Markers First. Each frame needs only 1 marker, and the alignment strategy is “geometry + markers, with markers prioritized.” This is particularly suitable for large castings with simple shapes and few pronounced edges or curved features. If tracking is lost during scanning, at least 2 markers must be recognized to restore positioning, so keep marker distribution continuous.

Q4: What resolution should I use for large castings?

A: Use ≥ 0.5 mm point spacing for contour capture or reverse engineering. For general inspection, point spacing can be increased to ≥ 0.7 mm. Use a local fine scan at 0.1–0.2 mm for critical areas.

Q5: How should I scan deep holes and blind spots in a casting?

A: First scan the part to establish an overall framework. Then switch to the 3DeVOK MT Gen2’s single-line blue laser mode to scan deep holes and blind spots, improving data completeness in hard-to-reach areas.

Q6: Do highly reflective castings need a powder spray?

A: The MT Gen2 handles reflective materials well, so ordinary castings generally do not need powder. If noticeable noise or stray points remain after increasing laser brightness, apply a developer spray and then scan with markers.

Conclusion

Scanning large castings efficiently depends not only on scanner performance but also on the scanning mode, marker layout, and point spacing.

When scanning a large casting with the 3DeVOK MT Gen2, choose between blue cross-laser marker-based alignment and infrared structured light + Markers First according to the workpiece size, surface features, and accuracy requirements. Combine an overall scan with local fine scans to maintain data completeness and stable alignment while reducing unnecessary data capture and post-processing.

Choosing suitable equipment and a well-planned scanning strategy helps make 3D digitization of large castings more efficient and reliable.

About 3DeVOK & SCANOLOGY

SCANOLOGY draws on more than a decade of expertise in industrial 3D scanning, backed by a company listed on China's STAR Market. Its technology serves the automotive, aerospace, energy, heavy industry, railway, and shipbuilding sectors, among others. Committed to innovation and reliability, SCANOLOGY delivers high-precision, portable, and intelligent 3D measurement solutions to customers worldwide.

3DeVOK, a brand of SCANOLOGY, focuses on professional 3D scanners for applications including automotive customization, medical rehabilitation, museum and cultural heritage digitization, education and research, art and design, and maker projects. Committed to making professional 3D scanning easier and more accessible, 3DeVOK empowers users to bring their ideas to life.