Hope Never Dies:Cross-Age AI Tech Brings The Lost Children Home!

Parents of missing children will never stop searching for their children but after years and years they often give themselves closure by saying, (we) “don’t expect (our children) them to come back to us, (we) just want to know where they are, look at them, know how they are doing.”

Between 2006-2014, 10 children went missing. Sichuan Provincial Public Security Department and Public Security Authorities determined through investigation and various evidence found that these children were abducted and sold in Guangdong. However, no results were obtained through the national DNA database comparison of anti-trafficking.

Over the past 5 years, the Sichuan Provincial Public Security Department and Public Security Authorities have actively been searching for these 10 abducted children. Through interviews, mock portraits, and undercover middlemen, though they’ve come up short.

That is until they received a breakthrough in December of 2017. 

Chen Shiqu, Deputy Director of Criminal Investigation Bureau of the Ministry of Public Security, learned about Youtu’s cross-age facial recognition technology. He approached Tencent for research and introduced this breaking technology to the Sichuan police force.

When colleagues received photos from the parents of the 10 abducted children, everyone was silent. Photographs were wrapped in thick oiled paper for fear of contamination. Most children were under the age of three and some parents only had 1 photo of their child.

Jiang Xiaoming, Director of the Anti-Trafficking Department of the Criminal Investigation Bureau of the Sichuan Provincial Public Security Department, recalled that many parents repeatedly told them not to lose the photos.

“For many parents, these photos are the only thing left of their children.” she said.

“We didn't know if the technology would work and be beneficial for investigation but when we received the thick packages of pictures, we decided to give it a try.”

At the time, there was no success with finding a missing child by facial recognition technology. Since many of the children were under the age of 3 when they were abducted, by the end of 2017 the would be anywhere from 8-13 years old. 

There can be a dramatic change in facial features during this time period. 

Dr. Li and his colleagues, who lead the research of optimal face recognition algorithm, simulated and modeled the growth and change of faces from 0 to 18 years old, generated a large number of face samples for learning, and then used the deep neural network algorithm to learn the complex changes of these faces during the growth process.

They came up with the idea of "teaching machines by machines". After thousands of model trainings, a deep neural network model can be trained for age facial recognition.

"In a nutshell, it's like I'm using an adult face recognition model as a teacher, and I'm using a child face recognition model to learn the 'tricks' and try to eliminate the negative impact of age on recognition accuracy." Dr. Li said.

After nearly 6 months of hard work and many nights of burning the midnight oil, they finally made a breakthrough. The algorithm model, known as a distributed distillation learning algorithm, has an accuracy rate of more than 96% for age facial recognition.

According to Tencent Youtu lab's cross-age facial recognition technology, police conducted further DNA paternity tests and found 4 children who had been missing for about 10 years. 

“It's a first for the country, and it's really a remarkable breakthrough!

As of now, 7 of the 10 children abducted in Sichuan have been recovered. It is fully proved that artificial intelligence can play an important role in finding abducted children for many years. In addition to DNA comparison, this technology of cross-age facial recognition provides an effective way for the public security organs to find abducted children, which is milestone.

At present, there are only a few dozen cases of child abduction and trafficking carried out by criminals in the form of theft, robbery, and abduction. A total of 6,108 children have been abducted.

Police are also considering applying Youtu's cross-age facial recognition technology across the country.

According to Dr. Li, their team is also optimizing the cross-age facial recognition model with an accuracy rate of more than 99.80 percent, which will challenge a larger age span.

The power of technology is amazing!

Editor: Crystal Huang

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