In today’s market, it seems like all 3D scanners have similar specifications as if manufacturers look at their competitors’ data and use the same numbers. Datasheets, marketing videos, and even product appearances all look comparable, making it difficult to distinguish quality based on technical data alone.
So, when faced with multiple options, how can we identify a high-quality 3D scanner?
In this article, we introduce 3 practical tests that require no calibrated artifacts to determine whether the performance claimed on technical specification sheets is achievable in real-life scenarios or just numbers without tangible value on paper. The purpose of these tests is to help you identify which manufacturers have rigorously developed and tested their 3D scanners.
Form Defect Measurement (Cylindricity)
A form defect in GD&T is the deviation of a machined part from its ideal shape. This measurement indicates the quality of a 3D scanner by revealing its ability to measure true-form defects.
Test #1: Cylindricity Test
Further, when assessing the quality of a 3D scanner, the extensive point filtering process focuses primarily on the raw data. No doubt, noisy and low-quality raw data will lead to questionable 3D models.
The Result: A Cylinder or a Mushroom
If you cannot obtain a good cylindricity value and clearly see the edge of the cylinder at right angles at high resolution, it suggests that the sensor is capturing poor-quality raw data. This raises concerns about the entire data capture and analysis process. When a cylinder looks like a mushroom, it indicates that the 3D scanner’s raw data is noisy. As a result, the software uses reconstruction algorithms to smooth the cylinder’s body and edges (and make the data look better), creating a mushroom shape. However, these algorithms can cause various unintended effects.
Poor-quality raw data with lots of noise means a thick point cloud. Therefore, how do we know where the real surface is in this point cloud? How can we ensure the mesh is created using accurate raw data and real surface points? Are there any hidden smoothed surfaces at high resolution that might affect the accuracy of the mesh?
Mushroom effect visible with a low-quality 3D scanner
As a pioneer in handheld 3D scanners, Creaform ensures high-quality data with minimal noise, enabling surface reconstruction algorithms to deliver consistently superior results.
Evidence supporting the claim: Cylindricity measured with Creaform’s MetraSCAN BlackTM|Elite
Test #2: Volumetric Accuracy Test
This test aims to show the consistency of the 3D scanner’s measurements. A high-quality 3D scanner must be repeatable, i.e., produce repeatable measurements with minimal variation. In contrast, a low-quality 3D scanner may give inconsistent results across repeated measurements or different operators.
To ensure consistency, operators must group measurements taken multiple times on the same part. In the repeatability test, one operator takes five consecutive measurements, while in the reproducibility test, five operators each take one measurement. The results from both tests should be presented in grouped formats.
A calibrated reference tool or artifact is not required to assess volumetric accuracy. You can measure any part within a certain period (e.g., same day, same hour). The results are even more evident on large parts.
The Result: Same Part, Identical Dimensions or Not
If operators do not group the results, it is a good indicator that the datasheet probably claims the wrong volumetric accuracy.
Ungrouped results obtained with a 3D scanner of similar price (gray columns) compared with the volumetric accuracy measured with the Creaform HandySCAN Black+TM|Elite (Blue columns)
If a 2-meter measurement varies by over 30µm or a car’s dimension changes by 2mm between attempts, the scanner’s claimed precision of 15µm/m or 1mm/m is questionable. When results differ, which one is accurate? During its early R&D, Creaform faced similar challenges but gained the expertise to overcome them. With a 10-year innovation lead, Creaform solves problems others still face.
Test #3: Thermal Stability Test
Another indicator of a 3D scanner’s quality grade is its performance under varying environmental conditions, such as temperature. Manufacturers design high-quality 3D scanners to remain stable under different conditions, while poor-quality scanners may react more to environmental changes.
Another way to distinguish high from low quality is the frequency to which the 3D scanner requires recalibration to maintain accuracy. High-quality 3D scanners generally remain calibrated for longer periods. In contrast, poor-quality 3D scanners might drift quickly and require frequent recalibration.
To perform this test, simply connect your 3D scanner and measure a part, any part. Then, repeat the measurement after 20 minutes, 1 hour, and 2 hours. Then, place the results on top of each other. Are the results consistent?
The Result: Constant Recalibration Required or Not
Drifted results obtained with a 3D scanner of similar price (gray line) compared with the thermal stability measured with the Creaform HandySCAN Black+TM | Elite over 15 minutes
With high-quality 3D scanners, various mechanisms (mainly software) manage thermal expansion within the sensor, ensuring stable and reliable measurements over a long period of time. However, these mechanisms are absent for low-quality 3D scanners, so results tend to drift.
The solution to address repeatability and thermal drift issues is to recalibrate the 3D scanner. However, it can quickly become inconvenient, even painful, for users to recalibrate their sensor each time they use it throughout the day.
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