Did you know there are cameras out there that can take pictures of sound? ipXchange didn’t, but gfai tech have been doing it for years. They can measure image vibration from DC into the audio range, and with WaveCam, you can too. All you need is your phone camera!
In this rather intriguing ipXperience, Eamon chats with Benjamin from gfai tech about the mind-blowing world of seeing sound through a camera. Yes, you read that right: gfai tech can capture images where the level of sound and vibration is noted across the scene!
How gfai tech measures the sound of an image
gfai tech’s WaveCam is a software that accepts video data in standard formats. You can use anything from a mobile phone camera to an industrial camera to produce the raw data. Inbuilt algorithms then determine the vibration level at all points in the image, allowing you to visualise sound/vibration and the structural properties of an object.
The frame rate of the raw data determines the vibration frequency range that can be measured. The higher the frame rate, the greater the frequency range and the more data you can gather. A standard video at 30 frames per second can capture vibration at up to 15 Hz, from Nyquist’s theorem.
But, as Benjamin highlights, many phones do have a high-speed mode: the latest iPhones can film at up to 240 frames per second for vibration capture at up to 120 Hz, and some Samsung phones can exceed 1000 frames per second for over 500-Hz measurements. This is definitely getting into the audio range!
Why would you want to take a picture of sound?
The high flexibility of WaveCam enables its use in a many structural monitoring applications. This includes automotive break analysis, industrial predictive maintenance, building analysis, and electronics board testing for high-vibration applications.
By observing how these objects behave when excited by certain frequencies, engineers can determine what modes of vibration could cause damage. They can then alter the design or put measures in place to mitigate against this damage. For skyscrapers in earthquake-prone areas, as an example, this is essential.
gfai tech’s solution effectively creates an array of virtual vibration sensors for frequency and time data on each pixel of a video taken by your choice of camera.
Why use WaveCam over traditional methods?
Physical vibration sensors and laser-based measurements have their merits, but they introduce many complications and cost implications when compared to WaveCam:
Adding a physical vibration sensor to an object can fundamentally change the resonant frequencies, making the testing inaccurate or just downright pointless. It is also not viable for smaller objects and requires a lot of computer modelling and setup time for analysis.
Like WaveCam, Laser doppler vibrometry is contactless – so it does not affect the resonant frequency of an object. That said, it is very expensive and not so easy to use, especially when compared to simply pointing a camera.
The limitations of video-based vibration monitoring
The main limitation of WaveCam is frequency range, but Benjamin has already worked with setups measuring vibration at up to 5 kHz using this technology. Beyond that, things get difficult as the frames are so short that good lighting is essential – the exposure for each frame becomes the issue as an image still needs to be captured.
The size of the video files also becomes massive. This puts strain on both the software and the computer hardware for handling all this data. Laser vibrometry is therefore the current way forward for measurements up to 30 kHz.
Additionally, WaveCam requires an optical reference on the object. The algorithm tracks the pixels, so uniform surfaces require preparation – marking – before making a measurement. WaveCam is, therefore, best suited for more complex objects.
Evaluating WaveCam
As long as you have a good PC, you can get started using WaveCam today with a trial license supplied by gfai tech. You can also send your own video files to its team for analysis.
If you have a commercial project and are interested in working with gfai tech, head to our user-defined board page – link below – to apply for a consultation. Don’t forget to specify gfai tech in the project description.
Full-hardware acoustic camera setups
Eamon and Benjamin then discuss gfai tech’s hardware-based acoustic cameras that use beam-forming technology and feature a lot of microphones combined with an optical camera. Sometimes a great conversation just keeps going, and this is less relevant to design engineers per se. This is for R&D engineers needing a test and measurement device.
This second discussion starts at around 17 minutes into the interview, so enjoy it if you’re interested in taking pictures of vibration into the ultra-sound range. We won’t spoil the details, and it’s a great discussion if you’re into predictive maintenance and animal sounds. You can still ask for more information about this technology by using the form on the user-defined board page.
Keep designing!