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Inventor Connections February 2005
Direct Dimensions Breaks New Digital Imaging Ground
By Lynda Rutledge
The ability to digitally scan an object, import the scan data into a CAD system, and end up with a highly accurate 3D solid model within a matter of days is a compelling concept for designers and engineers. It’s no wonder, then, that 3D laser scanning is beginning to see wide-spread use. Industry analysts tell us that the technology is being adapted not only for reverse engineering, evaluating, and reworking models in the design realm but also for projects in the AEC realm, such as creating an as-built model or tracking the progress of a construction job.
The latest research indicates that sales of 3D laser scanning devices reached new heights in 2004. While analysts predict demand will drive down scanner prices in time, costs are not expected to drop significantly this year. More affordable “rental” options have become available, but with prices for high resolution scanners in the six figures, owning the technology — however appealing — will likely remain out of reach for small and mid-sized businesses for the time being.
This is where 3D imaging service providers like Direct Dimensions, Inc. (DDI) come in. Specializing in the on-site application of portable coordinate measurement machines (PCMMs), digitizers, and laser scanners, this Maryland-based company is taking digital imaging in bold new directions.
Using an array of scanning systems — including a portable combination CMM/laser scanner — DDI has measured and modeled NASA space shuttle components and scanned human limbs to create perfectly-matched prosthetics. Consumer projects have included reverse-engineering a line of fast food kid’s meal toys and scanning the head and upper torso of Baltimore Ravens linebacker Ray Lewis for the creation of a marble bust. Other, still more high-profile projects have included scanning priceless works of art and national monuments for historical preservation. Among these projects have been digitizing the Lincoln Memorial and the Liberty Bell.
An Extensive Toolkit
DDI was established in 1995 by an engineer who helped develop the FARO Arm® portable CMM, the first ever seven-axis contact digitizing device for a manufacturing environment. Today, 10 years later, digital imaging knowledge and experience abounds at DDI. The company’s digital imaging capabilities range from simply capturing a few dimensions on a geometric part to creating a complex free-form surface model of a sculpted design or a fully parametric 3D solid model that can be integrated into mainstream CAD systems. And given that the company is an authorized sales representative of several leading 3D scanning and digitizing systems – DDI sells some 12 different devices from a number of manufacturers – DDI engineers can assemble and apply just the right combination of tools to handle projects that require capturing large scale views (of a building’s interior, for instance) or super-fine surface detail (such as the lettering on the Liberty Bell) — or both.
Resembling an artificial human arm, with a shoulder, elbow, and wrist, the FARO Arm was originally used in medical applications for measuring spine curvatures and other body-gauging applications. Michael Raphael, DDI’s co-founder, president and chief engineer, played a key role in FARO Technologies’ repurposing of the machine for industrial applications.
Back in the late 1980s, when Raphael was working as an engineer for a large aerospace manufacturer, he and his co-workers were starting to design aircraft parts in 3D (using CATIA software). They were assembling some very large aerostructure components, and they were having trouble understanding some of the complex contours in 3D. They had few tools they could use on the factory floor, however, to measure in 3D. CMM technology had been around awhile – at least 20 years from a manufacturing standpoint, but the machines were very large and required specific facilities. They also employed both photogrammetry solutions as well as computerized theodolite systems. But often, Raphael and his colleagues were forced to take apart the structures and haul the parts to the CMM area for more detailed measuring.
Then, in the late 1980s, Raphael spotted FARO Technologies’ measuring device. Seeing its potential for solving his quality control difficulties, Raphael partnered with FARO to help the company understand the specific requirements needed to convert the device from a medical to an industrial tool.
By the mid ‘90s, Raphael had quit his job at the aerospace company and started Direct Dimensions, initially reselling the FARO Arm and providing measurement and engineering services both at his facility and at customer sites. The projects kept coming as customers realized the speed and accuracy possible with the FARO Arm. “We can arrive at a site with the FARO Arm and scanner and start scanning in 15 minutes to a half hour,” noted Raphael.
But Raphael soon realized he needed a wider range of digitizing technologies to handle the varying types of projects he was taking on. “No one tool even comes close to doing it all,” he notes, pointing out that he often uses different methods of measurement for different aspects of a single project. He began to adopt some of the newer, high-resolution laser line scanners from companies such as Kreon in France and Perceptron in Michigan that are capable of capturing several million data points in a single scan.
Raphael and his team also use modular-type, long-range laser scanners with large fields of view, such as iQvolution’s iQSun, capable of scanning entire factories.
Raphael also came to discover that no one software package does it all, either. To deal with the CAD integration issues involved with getting huge point clouds into a CAD system. Raphael and his team have adopted several of the reverse engineering and digitizer data incorporation products that have come out over past five to ten years. These include InnovMetric’s PolyWorks, products by Raindrop Geomagic, UGS Corp.’s Imageware, and others.
While gaining 3D measurement experience over the past 10 years, DDI developed its ScanSys® product line of 3D imaging solutions. One version of the ScanSys® provides wide range and mobility using 3D imaging cameras that can also capture colors in 3D. Another system uses a laser line scanner attached to an articulating arm similar to a human arm. This system provides mobility with higher resolution. And another version of the ScanSys® product line, providing the highest accuracy, is a laser scanner mounted on a computer controlled motorized CMM. All ScanSys® systems can be supplied fully integrated with modeling and analysis software and provided with customized application-specific training from DDI’s expert users.
One of the more widely used ScanSys systems is based on the FARO Portable CMM. The FARO Arm gathers data by measuring angles to position objects in space within 1000ths of an inch. Users collect simple X, Y, Z point variations with the Arm’s probe and attached laser scanner to capture data at a rate of several thousand points per second. The CMM machine tells the laser scanner where it is in 3D space, while the scanner passes a red line laser wand over the object’s surface to collect point clouds. Together, the two technologies capture the millions of data points that allow for the creation of highly complex and accurate surface models. “CMMs have lots of accuracy as a machine, says Raphael, “but when you add a high-resolution scanner to a conventional CMM, you can practically scan a fingerprint.”
Years of application experience on a wide variety of projects has allowed Raphael and his team of 12 engineers and technical staff (at present) to amass a depth of knowledge about this relatively new technology that few have. “One of our biggest skills,” he notes, “is knowing what to do when, knowing how to do it, and knowing what solutions to use.”
In recent years, says Raphael, customers requesting DDI’s measuring services on non-traditional projects have been “coming out of the woodwork.” Projects of this sort completed by DDI number into the hundreds. Here are just a few examples:
Replicating the Liberty Bell
The Liberty Bell project came about in the spring of 2004 when DDI was approached by the owners of a centuries-old French foundry who had decided to create a replica of the original 1752 bell — now housed at the Independence National Historical Park in Philadelphia. The replica was for a celebration that June honoring the 60th anniversary celebration of the Allied invasion of Normandy, or D-Day. The goal was to make the replica as close as possible to the original design. Here’s how Raphael described the challenge to a Time-Compression Technologies reporter shortly after beginning the project. “How precisely can we measure what we’ve got and back into what we think the designers of this bell intended this thing to look like — and sound like?” Raphael and his team of engineers performed the scanning one evening in February ‘04, after the building was closed to the public. “We loaded our van with our FARO arm, a Perceptron laser scanner, and a Minolta Vivid 3D laser scanner.” The chief curator of the Independence National Historical Park and a National Park Service ranger were on hand to observe the process — and to ensure that no equipment actually touched the priceless Liberty Bell.
Raphael and his team performed an initial scan with the Faro Arm and Perceptron scanner mounted on a mobile stand. They were able to record in great detail all of the lettering, scratches, and imperfections on the bell, including its famous crack, which historians say extended to the point of making the bell unringable on Washington’s birthday in 1846. The Vivid 3D laser scanning imaging camera from Konica Minolta, mounted on a tripod, provided redundancy and overall data coordination. The entire scanning process was completed in six hours, and DDI came away with a hundred precise 3D scanned images from the Vivid 3D and millions of cloud data points from the Perceptron. After preliminary processing, Raphael and his team got to work on a complete engineering analysis of the data, painstakingly evaluating the dimensional and geometric characteristics of the model to arrive at the design intent of the original bell.
Raphael discarded the data from the bell’s crack in order to better capture the tonality of the original Liberty Bell, and the foundry cast a bell from the model that would provide a sound unheard by generations. Said Raphael in the above interview, “They [the foundry owners] like to say they are putting the voice back into the Liberty Bell, and we are helping them to do that.”
Preserving the Lincoln Memorial
DDI used a mix of digitizing tools to measure the Lincoln Memorial in Washington, D.C., a project prompted by the September 11, 2001 attacks. Shortly after the attacks, the federal government asked DDI and its partner company to measure the Lincoln Memorial so that it could be reconstructed in the event of further terrorist attacks. The idea was that, working from 3D models, curators could accurately recreate the Memorial — in whole or part.
DDI worked on the project in coordination with Spatial Integrated Systems, Inc., a 3D modeling and visualization company. They faced the challenge of scanning the front columns, some of the steps leading up to the chamber, the entablature, the statue of Lincoln in his chair, and the wall directly behind the statue, including the inscription — all while minimizing disturbance to visitors. The teams roped off a small working area and used batteries for their equipment to avoid running power cords across the chamber. They were given one day to get demonstrate their equipment and do initial scans. Using the Cyra Cyrax Laser, they took close to 20 shots to scan Abe and the chamber’s interior detail, scanning from about 40 feet away. The teams also captured the front stairs and columns, taking these scans from up to 100 feet away.
DDI performed the post-processing over the next several weeks to create the STL files that could be used for rapid prototyping a 3D model of the Memorial — one that would show such fine detail as the chisel marks on the statue.
Preserved for Posterity – and Ravens Fans
Perhaps less historically significant, but nearly as intriguing, is the work DDI did for the Ray Lewis 52 Foundation to create a marble bust of Baltimore Ravens Linebacker Ray Lewis. DDI used the Konica Minolta Vivid 3D Imaging Camera to scan Lewis’ head and torso. Using Innovmetrics’ PolyWorks software to create a lifelike STL file, DDI rapid-prototyped the bust, which was then rubber molded and cast in marble resin. The bust was auctioned at the Foundation’s Second Annual Cocktail Party and Auction in May 2004, with the proceeds benefiting Ray Lewis’ Foundation.
I haven’t even touched on DDI’s many fine arts preservation projects, including the company’s help in the creation of a life-sized 3D model of a dancing couple depicted in a well-known painting by French Impressionist Painter Pierre-Auguste Renoir. I’ll have to assume that those still reading up to this point will check out more examples from DDI’s vast collection of customer stories and images on its website at www.directdimensions.com. Direct Dimensions staff have recently added a very cool new online 3D visualization tool that can show off some of these case study projects in full 3D.
Asked to forecast future trends in digital imaging and modeling, Raphael said that it’s difficult to say where the technology might go, but he did tick off this list of predictions:
• Accelerated demand for 3D digital imaging.
• An increase in the use of digital scanning for medical applications. In a project that made national news in the summer of 2004, DDI worked with Johns Hopkins Hospital in a pre-surgical analysis involving 13-month-old conjoined twin girls. DDI volunteered its time and equipment to laser-scan the twins’ conjoined heads and construct first a virtual, then a physical model that allowed surgeons practice the procedure and determine a surgical plan. (As it turned out, one of the girls died during the surgery, but the other is doing very well today). (See Figures 11-12).
• An increasing demand for turning more and more types of objects into 3D for sharing visual information, including collections of objects. Raphael was recently approached to scan a collection of valuable, one-of-a-kind duck decoys, and he’s currently meeting with Baltimore museum officials about scanning the museum’s entire collection to create a multi-media, virtual museum tour. “Laser scanning technology collects color as well as shape,” notes Raphael, adding that DDI can scan a building or room and create a representation with a degree of accuracy that makes visitors feel as though they’re practically there. He also sees the technology being used for collaboration in science and academia.
The possibilities for laser scanning technology — whether industrial, commercial, civic, and artistic — seem endless, as does the creativity and stamina of Raphael and his staff at DDI. Expect to hear more from this company in the near future.