AI model trained to recognise fireworks more quickly after explosion
Incidents involving heavy-duty fireworks occur daily. The fireworks are used in attacks on homes, out of a desire for destruction or as weapons against the riot police. Together with the police and the Netherlands Public Prosecution Service, the Netherlands Forensic Institute (NFI) has developed a web application (vuurwerkverkenner.nl) to make the investigation of such incidents easier.
Investigating a firework incident is no easy task. The firework has been blown into countless fragments, often distributed over a wide area around the scene of the crime. In order to be able to conduct the investigation, it is essential that police officers know what type of firework was used and what they need to look out for. The application helps the police to immediately recognise which firework has exploded (assuming it was a professional firework), based on photos of fragments. The web application also provides relevant associated information.
AI models
The idea to develop the web application was suggested by the NFI’s Explosions and Explosives team, explains NFI expert Jan Dalmolen: “Firework fragments need to be examined following explosions, but the capacity of NFI experts is limited. The investigation in itself is not very complex, you just need to have a lot of knowledge about all the possible types of fireworks.”
The NFI’s Forensic Big Data Analysis (FBDA) department has experience in training AI models to recognise images. Dalmolen: “We wanted to see whether we could train a model to recognise firework fragments. That’s how the idea for the web application was born.”
Thousands of fragments
A team from FBDA then helped the Explosions and Explosives team to train the AI model. “We knew it was achievable, but we also knew it wouldn’t be easy”, says Kim de Bie, data scientist at the NFI. They were twice awarded grants from Innovation Court to explore and further develop the web application.
The NFI experts trained the AI model by showing it examples of fireworks, both intact labels and fragments. For this purpose, they had the Ministry of Defence’s explosives disposal service EOD blow up hundreds of items of heavy duty fireworks. Thousands of fragments were then collected and photographed, producing high-resolution images. The fireworks for the investigation were provided by the Public Prosecution Service’s Office for Financial, Economic and Environmental Offences and were obtained from seizures.
Trace evidence
Raoul de Graaff, forensics specialist at the Noord-Holland police unit, is convinced that the application will help in investigations. “When you are conducting an investigation after an incident, it is essential that you know which type of firework was involved. By identifying fragments at the scene of the crime, the application tells police officers what other fragments of the firework they need to look for on the street. Those fragments can contain trace evidence that leads to the perpetrator.”
Illegal fireworks come in all types and sizes – the so-called Cobra alone exists in dozens of varieties. De Graaff: “If we know exactly which type of firework was used, we may be able to use that knowledge to link different incidents. And if we encounter a specific type of firework in a suspect’s possession, for example one used in attacks, that can serve as evidence.”
Information about risk of endangerment
What’s more, says De Graaff, the application provides information about the firework. “For example, about the so-called risk of endangerment. Or in other words: how powerful the firework is. This is relevant for police officers on the street if they discover unexploded fireworks, but it can also determine which offence a suspect is subsequently prosecuted for.”
The web application can be used by any police officer on the street. “We have decided to publish everything open source”, says De Bie: “That is government policy. We make it public unless there are compelling reasons not to do so. In this case, there were none. It also makes us accountable. Everyone can see how the model has been trained and how it works.”
Complex investigations
In the future, the police will only need to request the help of an expert from the NFI if they need confirmation that a particular type of firework was involved or want to know how dangerous the explosion was in a specific situation. Are the NFI experts not concerned that they may become redundant? Dalmolen laughs: “Not at all. The fireworks application needs to be kept up to date. There will be new firework articles in the future and they will need to be added to the database. Plus, with all those explosions, there is plenty of work to be done. Thanks to the web application, the NFI has more time to focus on more complex investigations and we can really use that time.”
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