What is Video Metrology and How Does it Work?

What is Video Measurement?

In manufacturing, video measurement is optical technology producers use to check the quality of products. Industries like automotive, electronics, aerospace, medical, and military use optical metrology to improve the quality of their products by using the light spectrum and high-powered lenses to detect product flaws.

Video measurement quantifies the physical quantities and characteristics of video data streams. This process is called video verification, image quality assessment, or digital watermarking. Video measurement is quantitative and objective, requiring a numerical value and associated probability for each measured characteristic. While the video data may still be subjective, the measurements are not. A video measurement system requires an objective measurement device and methodology to function properly.

The main objective of video measurement is to determine whether or not a measured characteristic meets its image quality target value. This is typically performed as statistical analysis. If the measured characteristic falls outside its target range, the manufacturer must determine why this happened.

Industries can use video measurement systems for many purposes, such as certification and inspection, product quality control, decision support, and vendor management. Video measurement is often applied to check the quality of products such as automotive components, electronic components, and hand tools.

The Two Parts of Video Measurement

Video measurement has two major parts: metrics and reference models. Metrics perform the actual measurements, whereas reference models contain the mathematical formulae that describe how metrics perform the measurements. Video metrics measure the characteristics of a video processing system's output.

The Process of Video Measurement

• Capturing the image.

• Decomposing the image into image features.

• Segmenting the image into regions of interest.

• Analyzing the information.

• Verifying that the product meets certain quality standards.

Some video metrics are based on human perception, called perceptual metrics. Examples of perceptual characteristics include brightness, contrast ratio, color saturation, and hue. Other video metrics are based on machine vision technologies, such as area and edge detection. The primary difference between perceptual and machine vision metrics is that perceptual measurements of standard video equipment are generally linear with magnitude, whereas machine vision measurements are not.

Video measuring devices offer fast, non-contact 3-axis coordinate measurement with industry-leading accuracy. This multisensory quantifying equipment can easily verify critical dimensions on first articles, production samples, or full runs.

Since its introduction, video measurement has come a long way; however, the basic concepts are still the same. The difference between today and in the past is that manufacturers have improved video measurement technology to make it more accurate, sensitive, and versatile. Furthermore, the cost of video measurement has decreased as well.

What is Video Metrology?

Metrology is the science of measurement and deals with applying precision measurement to all disciplines.Of course, there are countless measurement techniques, from simple ones like rulers to more complex techniques like radar engineering. But one area of particular interest is VMT, a discipline that studies video and vision through instruments.

VMT

Manufacturers utilize video technology to measure and verify the quality of their products, but how do they do it? Understanding VMT is a two-step process. First, there is a need to understand the principles behind VMT. Secondly, there is the need to understand the techniques used to perform video measurement in the manufacturing environment. This article will provide an overview of both aspects of metrological videography.

Video metrology (also known as VMT or metrological videography) is a multifaceted technology fast becoming the single most important application of imaging technologies in the manufacturing industry. This technology facilitates the process of quality control to reduce or eliminate product variability. VMT works by quantifying a product's optical and electronic signals to verify its quality. By using video technology, manufacturers can collect and analyze data from the environment, and by doing so, they can determine whether or not a product is up to standard. VMT also includes techniques that facilitate and improve the process of measurements, such as image segmentation and self-reference.

VMT is widely used in several medical, aerospace, automotive, and electronics industries. The VMT process involves six main steps: capture, decomposition, segmentation, analysis, monitoring, and verification.

Capture

Metrological videography uses video cameras to capture a product or component. This may be performed by using a camera with a high frame rate, which captures images at over 50 frames per second. The camera may also capture images in both color and black and white.

Decomposition

When capturing a video of a product, the video needs to be decomposed into smaller, more manageable, and useful images. Decomposition is done to investigate specific parts of the video footage, and decomposition may be performed using an optical or computerized method.

Segmentation

Segmentation involves splitting an image into smaller, more manageable regions. Segmentation is useful for manufacturers performing VMT on a specific part of the image.

Analysis

The analysis part of VMT is performed by analyzing the video information. The analysis will include:

• Identifying the location and distance of different features in the image.

• Quantifying and comparing the values to expected values.

• Extracting numerical data from images.

Various tools and techniques, such as computerized edge detection and optical flow, are also used to analyze video images.

Monitoring

The monitoring step involves monitoring the product's performance while it is being measured. The monitoring step is often considered the most important part of VMT because it is where quality control is done.

Verification

The verification step involves comparing the measured results of a product to its required specifications. If the results comply, then the product is considered verified. This step is part of quality assurance, verifying that a product meets certain requirements or specifications.

The History of Measuring

The history of measuring dates back to the beginning of human existence. Aristotle wrote a treatise on metrology around 340 BC. During this time, one of the metrology's main objectives was to standardize weights and measures. By the 16th century, metrology began to designate the standards and measurements used in conjunction with industrial production.

In the early 17th century, Galileo Galilei, considered by some to be the father of modern physics and astronomy, was an advocate of the use of metrology in industry. In his published works on mechanics, he mentions the need to improve the measurement of weights and measures.

The industrial revolution, often called "The Great Awakening," started in the 1700s with John Kay's invention of the flying shuttle for weaving. The 19th century saw the development of several metrology techniques and instruments. The early part of the 1800s was dominated by quantifying systems such as the slide rule and micrometers used to measure precise geometric dimensions.

Industry leaders in video measuring technology have been pursuing the possibilities of light for more than 100 years. It all began with the production of precision optical glass, and the glass was used to manufacture lenses for microscopes and telescopes. Since this departure in 1917, there has been significant growth in light use in several key industries. The development of light-based measurement techniques has significantly impacted these industries and continues to do so today. The decades following the inception of this new technique saw the introduction of polarizing and stereo microscopes, further enhancing the use of light in industrial quality control. The 1990s saw the development of new instruments and techniques, such as the Eclipse range of infinity optics.At the turn of the millennium, the industry giant Nikon unveiled digital imaging solutions like microscopy, further enhancing light's use in industrial quality control.

Nikon has diversified its portfolio with 3-D imaging products. The continuous innovations in this market give industry leaders the flexibility to meet growing market demand. 3-D imaging has given the industry a new measurement means, improving overall quality control.

Types of Vid

eo Measuring Systems and Techniques

VMT's objective is to measure and assess a product's quality systematically. VMT is crucial for many industries.

With today's technology, there are many ways of assessing the quality or performance of a component or product. Often, the assessment of a product entails two elements; part geometry and performance. Performance is typically measured by determining if a product meets or exceeds its requirements.

CNC Video Measurement

CNC video measurement systems can be used to assess the geometry of a product. If a product is manufactured with errors, it is important to eliminate or correct these errors before performing any quantifying operations. If there are no errors in the part geometry, it is important to ensure that the product's performance meets or exceeds its specifications.

Automated Precision Measurement

Automated Precision Measurement systems are metrological videography systems that allow for the measurement of complex geometries. Automated precision measurement systems are typically used for inspecting and verifying intricate parts.

The Manual Field of View System

This is also used to measure a product's performance and geometry using manual methods. With manual measurement systems, it is possible to use a handheld magnifying glass or loupe device. Manual systems are commonly used when only a gross measurement of the part is required.

Measurement By Parts

Measurement by parts inspection (MBP) is a non-destructive method where a component is assessed to see if it meets the specified requirements. Measurement by parts inspection combines visual inspection with measurement data. This is done by taking a video still frame of the component or product where the measurement data is recorded. These video still frames are then digitally analyzed and compared to the required specification. The difference between the two may then be used to determine if there is an inconsistency.

Minute Part Measurement

Minute Part Measurement is used by automotive, medical, and transportation industries to determine how fast a component or product moves. This is done using the mechanical measurements of speed and distance, and mechanical measurement can be done with a linear CMM, an optical quantifying system, or both. Minute part measurement is used to determine if there is a variation in speed or distance, which is important when estimating parts under varying conditions or for different tasks.

Time of Flight

Time-of-Flight (ToF) is a technique used to determine distance using light. The typical application of ToF is a 3-D imaging technique where the distance between two points is determined. The two points in question may be analyzed for geometric purposes or to determine if the part is out-of-tolerance.

Interferometry

Interferometry is an optical measurement technique to determine the distance between two points. The distance between the two points is measured in millimeters, and angular velocity is used to calculate the distance between the two points.

Conclusion 

These are only some types of metrology systems used in metrological videography. It is imperative to use the right technique for the right application. With the introduction of technologies, there has been a significant impact on industry leaders and those looking to enter the field of quality control.The end goal of any VMT process is to ensure that a product is consistently manufactured and meets or exceeds its specifications, and this is where the value of VMT lies.

Video measuring instrument working principle

 

The video measuring instrument is a high-precision high-precision camera composed of a high-resolution CCD color lens, a continuously variable magnification objective lens, a color display, a video cross-hair display, a precision grating ruler, a multi-function data processor, data measurement software and a high-precision workbench structure. Optical image measuring instruments.

The image measuring instrument is based on artificial intelligence technologies such as automatic edge extraction, automatic matching, automatic focusing, measurement synthesis, and image synthesis based on machine vision. Image map target guidance, full field of view eagle eye zoom and other excellent functions. At the same time, based on the automatic focusing process under the precise control of machine vision and micron, it can meet the needs of auxiliary measurement under clear images, and can also add a contact probe to complete coordinate measurement. Excellent software performance that supports spatial coordinate rotation, batch measurement and SPC result classification can be performed when workpieces are placed randomly or using fixtures.

Video measuring machine uses

Image measuring instrument is a high-precision, high-tech measuring instrument that integrates optical, mechanical, electrical, and computer image technologies. It is mainly used to measure two-dimensional dimensions. The items that can be measured by the image measuring instrument are:

1. Multi-point measurement of points, lines, circles, ellipses, ellipses and rectangles to improve measurement accuracy;

2. Combined measurement, center point structure, intersection point structure, line structure, circle structure, angle structure;

3. Coordinate translation and coordinate correction to improve measurement efficiency;

4. Collecting instructions, batch measurement of similar workpieces is more convenient and quick, and the measurement efficiency is improved;

5. The measurement data is directly input into AutoCAD to become a complete engineering drawing;

6. The measurement data can be input into Excel or Word for statistical analysis, a simple Xbar-S control chart can be cut out, and various parameters such as Ca can be calculated;

7. The image measuring instrument can be switched in multiple languages;

8. The automatic image measuring instrument can record user programs, edit instructions, and teach execution;

9. Large map navigation function, special 3D rotating lamp for knife mold, 3D scanning system, fast auto focus, auto zoom lens;

10. Contact probe measurements are available for purchase. The software can freely realize probe/image conversion for contact measurement of irregular products, such as ellipse, radian, flatness and other dimensions; it can also be directly imported into reverse engineering software for further processing with the probe!

11. The image measuring instrument can also detect the roundness, straightness and radian of circular objects;

12. Flatness detection: The flatness of the workpiece is detected by a laser probe;

13. Professional gear measurement function;

14. Special measurement functions for test sieves used by major metrology institutes across the country;

15. The automatic image measuring instrument has the function of comparing drawings and measured data.

Optical measuring device application fields 

The image measuring instrument is suitable for all application fields for the purpose of two-coordinate measurement, and is widely used in machinery, electronics, aerospace, molds, springs, gears, terminals, circuit board contacts, hardware and plastics, magnetic materials, electronic circuits, components, Measurement of watches, hardware stamping industry, ore industry, mobile phone accessories, home appliances, connectors, mechanical accessories, precision fixtures, plastics, hardware, computer peripheral industries, etc.

Optical measurement equipment accuracy

Accuracy is the fundamental of measuring instruments, and it is one of the very important indicators for users to choose instruments. The measurement accuracy of the image measuring instrument mainly depends on the quality of the image measuring head, the performance of the illumination light source system, the movement of the instrument and the positioning accuracy, and the quality and level of the software and hardware of the data processing and measurement are also extremely important factors. As an automated measuring instrument, the measurement efficiency of the video measuring instrument is one of the most important factors for customers. High measurement efficiency can reduce equipment investment, improve production efficiency, and reduce labor costs.

The two-dimensional image measuring instrument used for on-site measurement in the factory usually has a resolution of 0.001mm and a measurement accuracy of about (3+L/200) μm. The two-dimensional image measuring instrument used in high-precision measurement fields such as precision measurement and value transfer, the measurement accuracy is generally better than (1.0+L/300) um.