From Film to 3D: The Evolution of Motion Analysis in High-Speed Imaging

With the invention of high-speed cameras, the demand quickly grew - not only for qualitative observation but also for quantitative analysis. In the early days of high-speed imaging using 16mm film cameras, each frame was projected manually onto white paper or onto a projector screen with a blank sheet. Operators would mark specific points by hand - an extremely time-consuming process that required full concentration for extended periods.

Moreover, only 2D analysis was practical at the time, as 3D analysis would have been far too complex and time intensive.

As PC performance and programming techniques advanced, motion analysis software began to emerge, allowing direct import of digital high-speed camera data for movement analysis. This marked the beginning of what is technically known as data reduction, a highly relevant concept in high-speed imaging. In most sequences, only a small region of the image contains relevant motion, while the rest remains static and uninformative. By focusing solely on object movement, motion analysis significantly reduces the amount of data that needs to be stored and processed - compared to saving full video files.

Thanks to sophisticated tracking algorithms, automatic tracking soon became highly reliable. Today, even 3D tracking with six degrees of freedom (6DOF), while still challenging, has reached an impressive level of accuracy.

From the early days, AOS collaborated with leading motion analysis software developers to ensure compatibility between camera data formats and the tools used by industry professionals. This commitment continues today, and AOS is proud to remain an integral part of the motion analysis community.

As a general rule in all measurement applications, the same principle applies to high-speed image analysis:
The better the quality of the high-speed video data and the clearer the movement, the more reliable the tracking results.

Motion video analysis requires clear and precise data to produce accurate results. Two important factors must be considered:

1. Sampling frequency:
   The frame rate (sampling frequency) of the recording should be at least twice the frequency of the object’s motion. This is based on the sampling theorem, a well-established mathematical principle in measurement technology, which also applies to data acquisition with high-speed cameras used for motion analysis.

2. Image clarity (motion blur reduction):
   Accurate tracking depends on sharp images. A commonly used rule of thumb is:

   “The shutter time should be shorter than the time it takes for the object to move across one pixel.”

There are two ways to achieve this:

• Reduce the shutter time of the high-speed camera
• Use strobed illumination during recording

In the image series on the side, a mousetrap is filmed with a long shutter time. The result: the movement is blurred and difficult to interpret. While this might have some artistic value, it is not suitable for motion analysis.

In contrast, the picture below shows the same scene recorded with a significantly shorter shutter time. The frames are crisp, making it easier to visually follow the motion. This kind of high-quality input is essential for delivering accurate results with any motion analysis software.

 

It’s a common assumption that motion analysis combined with high-speed cameras is used mainly in automotive crash testing or defense applications—especially where precise trajectory analysis is required. While these are certainly prominent use cases, they represent only the tip of the iceberg.

Motion analysis based on high-speed video data provides valuable insights across a wide range of scientific and industrial fields. Here are just a few examples:

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Human Gait Analysis

In medical applications, patients recovering from injuries are recorded with cameras. Motion analysis software extracts movement data, allowing physicians and therapists to track recovery progress over time. Quantitative data provides objective measures to support clinical decisions and tailor rehabilitation programs.

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Sports Performance Optimization

In sports science, motion analysis is used to evaluate the interaction between foot and shoe, among other biomechanical factors. These precise measurements can help optimize equipment—like tailoring shoes to an athlete’s body—to gain small but critical performance advantages. Sometimes, that inch of improvement is the difference between winning and losing.

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Industrial Applications

In industry, precise timing and movement data are often crucial. For example, in the image shown, engineers analyzed the performance of a relay switch to ensure it met minimum switching times required to interrupt a power source. Surprisingly, they discovered an unexpected oscillation that could cause a dangerous "almost contact" state. Based on this insight, they were able to revise the mechanical design and improve safety and reliability.

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Bringing Insight to Every Frame

Motion analysis is about translating high-speed videos into facts and figures. AOS Technologies AG supports various third-party motion analysis packages and also offers a built-in point-and-click measurement tool in Imaging Studio V4, allowing users to obtain quick, actionable results directly from video footage.

Whether in science, medicine, sports, or industry, motion analysis brings clarity, precision, and measurable insight to dynamic processes.