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3D Forensics Capture Shoe Prints Instantly in Three Dimensions

Picture of Hanna Watkin
by Hanna Watkin
Nov 4, 2016

Researchers are developing 3D Forensics technology to capture high-resolution 3D images of shoeprints in snow and soil.

Watch any crime scene investigation show and you will notice the use of plaster casting to take shoeprints. Now, a 3D imaging system is in development that could enable 3D printed shoe-prints instead.

The National Institute of Justice has funded the project, giving it a two-year grant with $788,167. The 3D imaging system will allow investigators who have no technical knowledge to take high-quality images. The portable system will also have an intuitive user interface.

The technology is being developed by researchers at Purdue University’s School of Mechanical Engineering. They are cutting the costs of already available systems by one-tenth. Their system will cost only $5,000.

“This is the biggest contribution we are making to the forensics community,” said Song Zhang, director of Purdue’s XYZT Lab. “Current 3D imaging products on the market are very difficult to use. You need expertise to be able to capture good images. What we want to do is bring in some intelligence to the algorithms so the forensic examiner just has to click a button to capture good images.”

Watch the video below to hear Zhang explain the technology:

3D Forensics will Enhance Crime Scene Investigations

Zhang is working with two doctoral students and two forensic researcher scientists. The system will provide images with a resolution of 600dpi instantly, compared to the wait time of an hour for casting methods. This same 3D modelling data could conceivably be used as the basis of a solid 3D printed object.

Zhang and his team have invented a “binary defocusing technique”. This provides depth imaging by projecting LED light with encoded data onto soil or snow.

The light which bounces back has pre-encoded information. The system is then used to determine depth with just one camera. A laptop can be used to operate both projector and camera.

Forensic research scientist David Baldwin at the Special Technologies Laboratory said of 3D Forensics:

“Our project has promise to deliver a device that will improve the quality and accuracy of tire and footwear impression evidence. We plan to develop an affordable and easy-to-use system that will provide the forensic science community with more and better evidence from crime scenes.”

However, the team face challenges in developing a system which can take high-quality images on mixed soil, snow, diffuse and “specular” surfaces. Objects which evenly reflect light are known as diffuse, while bright highlights are reflected by shiny objects.

Zhang explains: “This specular light presents problems for 3D imaging because cameras do not respond properly to those highlights. So we have to adapt our sensor to be able to deal with both specular and diffuse light.”

The 3D Forensics project officially begins in January 2017.

Source: Purdue University

3D forensics

License: The text of "3D Forensics Capture Shoe Prints Instantly in Three Dimensions" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.

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