Invisibility cloak? A new sweater escapes detection by AI machines
New discoveries in transformation optics will one day pave the way for the realization of the dream
By Kiran N. Kumar
Invisibility cloaks have attracted science fiction with many Hollywood movies or Harry Potter series keeping it up to date. Soon we might see an actual “invisibility cloak” to hide us from vigilant cameras using artificial intelligence.
Scientists at the University of Maryland, College Park, in collaboration with Facebook Artificial Intelligence, have developed an “invisibility cloak” which is a colorful sweater to prevent machine vision from finding you. The contradictory patterns on the sweater escape the most common object detectors, making the person undetectable, therefore invisible.
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While working on testing vulnerabilities in machine learning systems, scientists have developed an impression on clothing that AI cameras cannot see. They used the dataset on which the “YOLOv2” computer vision algorithm is trained and designed a model to recognize a person.
Then they created an opposite pattern and turned it into a picture – a print on a sweater. When a person wore this sweater, they could hide from AI detection systems.
The colorful sweater features a stay-dry microfleece lining, a modern fit and a clashing pattern that evades most common object detectors.
“The YOLOv2 detector is eluded using a model trained on the COCO dataset with a carefully constructed lens,” the team explained.
The detectors work by taking into account thousands of “priors” (potential bounding boxes) in the image with different locations, sizes and aspect ratios. To fool an object detector, a contradictory example must fool all priors of the image, which is much more difficult than fooling the unique output of a classifier.
Is the invisibility cloak possible?
However, the claim of invisibility is not 100% accomplished but partially works and one cannot completely escape the security cameras however. Additionally, the opposing sweatshirts targeting YOLOv2 only achieved about a 50% success rate in the wearable test. “When measured in hit rate, sweatshirts with Yolov2 patterns achieve hit rates of around 50%, but they do not transfer well to other detectors,” the research authors write.
The first step in making an invisibility cloak was taken in October 2006 when a cloak was developed to channel microwaves of a particular frequency around a copper cylinder to make them nearly invisible but for a small shadow.
However, camouflaging a human-sized object to achieve the invisibility that was portrayed in Star Trek or Harry Potter remains a far-fetched dream since it involves working simultaneously with all the wavelengths, or colors, that make up the light.
In 2009, some scientists developed a cloak that made objects invisible to near-infrared light using technology that did not use metals, which caused light loss.
Another section of researchers from the Berkeley Lab and the University of California at Berkeley came up with the idea of performing masking at optical frequencies using non-conductive (dielectric) materials.
The first of its kind, the cape was constructed using a dielectric – or insulating material – which absorbs far less light than previous designs. In early 2011, a new cloaking system was announced that hides microscopic objects from visible light.
By using calcite, the crystal system was able to refract light around a solid object positioned between the crystals. It made the object invisible “for at least three orders of magnitude greater than the wavelength of light in all three dimensions”.
Read: A real-time invisibility cloak that can hide you from AI cameras (November 21, 2022)
Another in-context design marries tiny metal needles inserted into a hairbrush-like cone at angles and lengths that would force light around the cape, causing whatever is inside to disappear of the cone.
“It sounds a lot like fiction, I realize, but it’s very much in accordance with the laws of physics,” Purdue researcher Vladimir Shalaev said afterward. “Ideally, if we made it real, it would work just like Harry Potter’s Invisibility Cloak,” he said.
So, beyond the invisibility of the fictional world, perhaps these discoveries from the perspective of transformation will one day open the way to the fulfillment of the dream.