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What do U.S. federal investigators and anthropologists at the Smithsonian Institute have in common? They are both pioneering the use of 3D scanning technology to solve challenging mysteries.

Physical shapes hold clues that can be essential in solving tough cases, and a transformation is ocurring in how people work with them. Experts from diverse locations collaborate to solve today's mysteries, and sharing physical evidence requires either transporting the evidence or key personnel. Both are expensive, and fragile evidence can be damaged while enroute. Digital 3D models allow authorized professionals to gain quick access to the information they need, regardless of location. Software that analyzes and compares 3D models can provide hard data that can help to convince juries and experts alike. To gain these benefits, the physical shape must somehow be digitally captured.

3D scanning bridges this gap between physical and digital, capturing highly detailed and accurate 3D models of physical objects. While 3D scanning is not a new concept, the availability of affordable, portable, and easy to operate 3D scanners is now putting this capability within widespread reach. When 3D scanners first surfaced a decade ago, they were the cost of a luxury car and required multiple days of training to operate. Now, they're available for the price of a professional laptop and can be picked up very quickly by first time users.

There are two types of 3D scanners employed in forensics. Crime scene scanners capture a large overview map of a crime scene. This overview map is helpful in understanding the relative position of objects, but the objects themselves are rough 3D shapes. New "close up" 3D scanners capture individual objects in full color and high resolution 3D. This level of resolution allows you to experience the object as if you were actually holding it in your hand.High resolution 3D models can even be beamed back into the real world using a 3D printer.

Most 3D scanners today use lasers to measure 3D information. A laser stripe or dot is moved across a target, and is photographed by a camera at a slight angle to the laser source. Depending on how far away the laser strikes a surface, it will appear at different places in the camera's field of view. This type of capture method is non-contact, meaning it does not touch or affect the original physical sample. For fragile or important forensic samples, this is very important.

It's possible to create castings, but for some items there is a danger of damage to the original in this process. Optically capturing the shapes using a 3D laser scanner provides a portable digital 3D model without any damage to the original. Some 3D scanners also capture the color surface of a physical sample, producing a visually accurate replica that would not be possible with plaster casts. Plaster casts work very well for some applications but are still physical objects that are difficult to share across locations and take up physical storage space. Plaster casts are easily captured by a 3D scanner and can be converted into digital models to solve these issues.

One key feature for 3D scanners in forensics is ease of use. New technicians and graduate students need to be able to grasp the technology quickly, and start applying it right away. Learning complex techniques can add delays, and can also introduce uncertainty in findings. This requirement for a fast learning curve is shared by forensic labs across the country, where time is a critical element in solving cases.

The United States is home to some of the best known and most comprehensive forensics research facilities in the world. A team of U.S. federal investigators is pioneering a hybrid approach that allows them to capture complete crime scenes with selective "3D closeups" on key features.

3D scan of 18,000-year-old skull

3D scan of talus bone

To capture "3D closeups" of key physical evidence, a high resolution from NextEngine is used. The cereal-box sized scanning unit is mounted on a tripod and aimed at the target object. Multiple laser stripes sweep across the target, and are cross referenced to provide a high level of data accuracy and a clean 3D surface. Color information is also captured for a visually accurate 3D image of the target.

One example of where they are using "3D closeups" is to capture shoe impressions. Traditionally, this has been done through the use of plaster cast, but this process produces a physical replica that is still difficult to share between locations. There is also a speed boost using this new technique. Creating a complete and highly detailed 3D model of a footprint takes less than 15 minutes, which is 125% faster than traditional method of pouring a plaster mold.

Footwear evidence is often the most abundant form of evidence at a crime scene. It can be used to determine the make and model of a shoe, and information about the owner can be gained from the angle of footfall and weight distribution. In some cases, it can prove to be as specific as a fingerprint. Since suspects tend to move around, having instant access to the footprint from a crime scene can allow investigators to quickly check a detainee against this data, or compare crimes and determine whether they may have the same perpetrator.

The team also captures an overview map of the crime scene using the large format ScanStation scanner from Leica Geosystems. The ScanStation consists of a backpack sized scanning unit mounted on a heavy duty tripod. The scanner is moved around the crime scene to capture it from multiple angles. These different captures can be assembled together in 3D software to create a complete 3D map of the crime scene.

When crime scene investigators make a traditional 2D diagram of a crime scene, they are required to make subjective decisions about what will be measured and what will not. High profile items such as human remains, bullet casings, weapons, and signs of struggle will always be located and recorded. However, sometimes the real story is told by a less obvious object which might be easily missed. The yellow tape can't stay up forever, and this information can disappear long before the case is solved. The 3D overview map is a permanent recording of everything in the crime scene, and allows investigators to go back in time long after the yellow tape disappears.

To give a sense of the difference: a crime scene scanner would provide enough detail to identify a body part as a hand, and a high detail scanner would capture the lines and wrinkles on that hand. Together, they provide a highly comprehensive digital record that is easily shared and can be referred to in court-rooms months or years later.

Anthropologists must often apply forensics principles and techniques. Like a criminal investigation, there's usually a body. There are few witnesses to question, and the remains and anything found nearby is usually all anthropolgists have to go on. In one tough case, the use of 3D scanning technology helped the Smithsonian Institute's Natural Museum of History discover and communicate a key finding.

12,000 years ago, a race of tiny people lived on Flores Island in Indonesia. Over the course of their life, they would never grow taller than the size of a modern three year old child. The remains of an adult female, six other individuals, and their stone tools were discovered in a cave in 2004. She was quickly nicknamed the "Hobbit" after the diminutive people in JRR Tolkein's Lord of the Rings.

In the wake of this astonishing discovery, a fierce debate has raged among anthropologists. The scientists who discovered the remains believed they were of a new non-human species, but some critics claimed these hobbits were modern humans with a disease that resulted in smaller bodies and brains.

A number of scientists of different specialties have analyzed the remains to provide evidence for the debate. One key difficulty for researchers has been getting access to the remains. They are currently stored in Jakarta University in Indonesia, but have been moved to other less-accessible universities in the past. Professor Teuku Jacob of Gadjah Mada University, the main critic of the finding that the Hobbit is a new species, was temporarily loaned the remains for his research. During his attempt to make castings of the skull, it was damaged and needed to be reglued. Also, his cleaning of the skull with acetone prevented further studies to extract DNA. This sheds light on the importance of non-contact reproduction methods like 3D laser scanning. For one of a kind samples, damage must be avoided at all costs.

When Dr. Matthew Tocheri of the Smithsonian Institute went to Indonesia, he brought along some new technology with him: a portable cereal-box sized 3D scanner which he could easily carry aboard the airplane. His lab at the Museum of Natural History has several 3D scanners, and for this project he chose the same scanner used by the federal investigation team for 3D closeups.

He used this high resolution laser scanner to capture 3D models of the Hobbit remains. This would allow him to "take home" the remains to his lab at the Museum of Natural History, and to compare the bones precisely to those of other species.

Dr. Tocheri is an expert in the study of the wrist and ankle bones. While much of the debate had previously centered around the damaged skull, Dr. Tocheri was able to provide strong new evidence with his findings on several small bones inside the wrist: the trapezoid, scaphoid, and capitate. While they may be small, these bones play a key role in the mobility of the wrist, and what the species is able to accomplish. For example, the unique shape of the human trapezoid allows for a very effective overhand throw, a key capability in early human hunting.

When Dr. Tocheri first saw the Hobbit's wrist bones, he was surprised that they looked nothing like human wrist bones, and more closely resembled those of a chimpanzee. The next step was to compare the bones mathematically and prove this initial impression.

The skull, wrist bones, and other remains were placed one at a time on the automated turntable that came with the scanner. This compact disc sized device automatically rotated the bones to capture them from all sides. The different sides were then automatically assembled in the scanner's software to create a complete model.

Once the digital models were captured, Dr. Tocheri compared them to previously captured scans of chimpanzee and human wrist bones. The result: the Hobbit wrist bones were a close match to chimpanzees, and were very different from those of humans. Wrist and ankle bones are formed very early in a developing fetus, before the diseases or birth defects some scientists had speculated were present in the Hobbit could have taken effect. This provided significant evidence that the Hobbit was a different species, and not a modern human with a birth defect or disease. With full 3D models in their hands, this made it easy for the Natural Museum of History to communicate the finding and convince other scientists of its validity.

footprint impression

There are many parallels between criminal forensics and anthropology. In both worlds, the face of a body is highly instructive. In criminal cases, it can help to identify the victim. In anthropological studies, it can reveal what a close human cousin may have looked like. Just as the skull of the Hobbit was scanned, law enforcement agencies worldwide are using high detail 3D scanners to digitally record skulls and reconstruct faces. Once a skull has been scanned, they can reconstruct the face using 3D software, or perform traditional clay reconstruction by outputting the skull to a 3D printer. In either case, the original is not touched during this process, eliminating the risk of damage or the need to transport the skull to the artist.

Many physical samples are temporary or fragile in nature. From shoe impressions in the dirt at a crime scene, to the ancient bones of an unidentified humanoid in a cave, they represent precious information that isn't easily shared through physical means. Today's easy accessibility to 3D scanning technology makes it possible for any lab to permanently record this data, and provide it instantly to the people that need it.

Peter DeLaurentis is a product designer and applications engineer for NextEngine. He has worked with 3D scanning technology since 2001, designing software for 3D scanning and helping customers explore the time-saving and creative possibilities of this technology. NextEngine, Inc., 401 Wilshire Blvd., Ninth Floor, Santa Monica, California, 90401, www.nextengine.com

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