When discussing 3D scanners, a frequently mentioned concept is 3D scanning precision. How do you understand the concept of 3D scanning precision? What are the differences between accuracy, precision, and volumetric accuracy? If you're confused by these 3D scanning terms, then this article is for you!
In simple terms, the most common 3D scanning terms are:
[Efficiency of 3D Scanning] - It affects the speed of the scanning process.
• Dot spacing
• Frame rate (FPS)
• Field of view (FOV)
• Object size
【Accuracy of 3D Scanning】- It affects the "error between the 3D object and the actual object" and the "quality of the scanned object".
• Accuracy
• Precision
• Volumetric Accuracy
This article will discuss the "error between 3D objects and actual objects" and the "quality of scanned objects." (For information on "3D scanning efficiency or speed," please refer to: [3D Scanning Knowledge] 4 Secrets to Improving 3D Scanning Efficiency Revealed! )
Accuracy vs. Precision vs. Volumetric Accuracy
When performing measurements, accuracy and precision must be considered because they represent how close the measured value is to a recognized or established value. The International Organization for Standardization (ISO) refers to this as "Accuracy (Correctness and Precision) of Measurement Methods and Results," defining accuracy as a combination of random and systematic errors. Accurate data is particularly important for applications such as automotive modification and industrial manufacturing.
Accuracy
Under certain measurement conditions, the degree of deviation between the estimated value and the true value of a single set of multiple measurements can be understood as 'the degree of closeness between the measurement result and the true value'.
Precision
Under certain measurement conditions, the dispersion of measured values among multiple measurements in a single measurement is characterized by lower precision and higher standard deviation.
Source: SHINING 3D Accuracy, also known as repeatable measurement accuracy, refers to the stability (consistency) of measured values after multiple measurements under the same conditions. Just as an athlete shooting a target can consistently hit the center area, a 3D scanner's precision can be compared to the area hit on the target, while accuracy can be compared to the stability of multiple hits.
Volumetric accuracy
A formula derived from precise testing and calculation displays the error relationship between the measured value and the true value when scanning the volume change of the model.
Most 3D scanner manufacturers also specify volumetric accuracy, which is the accuracy over several captures, and the global accuracy decreases as the size of the scanned portion increases.
For example: 0.05mm + 0.15mm/m.
For example, if your part is 2 meters long, the scanner's accuracy will be 0.05 + (0.15 * 2) = 0.035 mm. This is a significant difference compared to the original single-scan accuracy! Therefore, volumetric accuracy is more important than single-scan accuracy, especially if you are scanning large objects such as cars.
Just a quick addition!!
• Some 3D scanners with integrated photogrammetry modules can use scan-based positioning stickers to mark the 3D architecture of an object before it is filled in. The markers are precise reference points for the 3D scanner, much like connecting dots in a drawing. By using the "architecture" from a photogrammetric source, your data will be more accurate.
• Photogrammetry is a 3D scanning technique that involves taking multiple photographs of an object from different angles to calculate its shape and size.
Factors affecting measurement accuracy
Regardless of the manufacturer or market positioning, the accuracy of a 3D scanner will fluctuate due to various factors such as temperature, data integrity, algorithms, and scanning angle. Therefore, it is essential to understand how to prevent accuracy deviations and obtain the most reliable and accurate 3D data.
1. Temperature
To ensure optimal scanning accuracy, it is also crucial to allow the scanner to warm up and maintain a stable temperature. Once the temperature has stabilized, calibration should be performed before scanning to achieve the best accuracy. The sequence of warm-up, temperature stabilization, calibration, and scanning will produce the most accurate results.
2. Data Integrity
Data integrity is a crucial factor affecting accuracy. Incomplete data can lead to inaccurate or distorted results, impacting the overall quality of 3D information. Therefore, ensuring data integrity and authenticity is essential to obtaining the most accurate results.
Complete data
3. Algorithm
From calibration to data processing, algorithms play a crucial role in 3D data collection. They are a complex set of mathematical formulas that ensure accurate reconstruction of scanned objects. Calibration is also a vital component of this process, ensuring the accuracy of the scanner and providing the necessary data for the correct operation of the algorithm.
4. Scanning angle
Ideally, the scanner should be as perpendicular to the object as possible. This positioning helps the scanner extract the markings more accurately, resulting in more accurate 3D data.
Scan with FreeScan UE
Scanning larger objects results in greater cumulative errors. However, some scanning methods can help reduce these errors, such as global marking and photogrammetry.
Global markers
Before scanning the point cloud, we can first scan the global markers, which allows the algorithm to optimize accuracy, obtain more precise data, and ultimately improve volumetric accuracy.
Photogrammetry
Photogrammetry can improve the accuracy of global marking data. We can import a suitable scale file and place a matching scale near the object before scanning, based on the size of the object. Generally, photogrammetry is suitable for measuring large components requiring high precision in industrial applications. Of the two methods, photogrammetry is considered superior to global marking.
Scan the aircraft model using photogrammetry.
Comparison of Measurement Accuracy of the SHINING 3D Metrology-Grade 3D Scanner Family
For objects requiring high precision and small size, we recommend using two models: AutoScan Inspec and OptimScan-5M Plus . AutoScan Inspec is fully automatic and more convenient to use, while OptimScan-5M Plus can handle objects that are slightly larger than AutoScan Inspec.
How should we choose the FreeScan series ? If the object we need to scan is large and requires high precision, we can choose FreeScan UE Pro , because it is equipped with photogrammetry, which can greatly reduce errors in the alignment process.
FreeScan UE Pro application
Finally, let's talk about the FreeScan Trak . Unlike other scanners, this one doesn't require you to attach labels to the object being scanned. If it's difficult to attach labels to large objects, you might consider using this scanner.
Now you're familiar with accuracy, precision, and volumetric accuracy, but still clueless about SHINING 3D's scanner?
▶ Click here to filter for suitable 3D scanner recommendations ◀ (Link to SHINING 3D official website )
Manufacturers' websites and specification sheets often feature many different terms. What really matters are volumetric accuracy and grid resolution, and how they meet your specific needs.
While technical specifications for accuracy and resolution can help in easily and quickly comparing different 3D scanners, they should not be the sole deciding factor. Brand certifications, history, software, and after-sales service should also be considered.
If you are having trouble choosing a 3D scanner, or are unsure what your company's case (and budget) actually needs?
-Contact Us-
SanDima is happy to provide you with one-on-one demonstrations and high-quality solutions!
Follow our fan page to stay up-to-date with the latest news: https://www.facebook.com/3dmart.com.tw/
https://www.instagram.com/3dmart/
Reference 1
Reference 2