portrait of the author, Dan Collins
Of More Than Two Minds, 1994
Sculpture created by the author using 3D laser digitizing and CNC milling
by Dan Collins,
Siggraph 2002 STUDIO
Associate Professor of Art, Arizona State University
OK, we all know how the virtual space of the computer gives 3D artists godlike power to create objects, avatars, animations, and interactive worlds.
But there are a host of professional 3D input and output methods available that are still barely on the CRT of most of the 3D artist community. These techniques—some tried and true, others hot off the press—can serve to broaden the palette of animators, 3D web designers, and digital sculptors.
A few pioneering artists have discovered the power of 3D capture devices operating at full range of scales—from the nano- to the planetary. Others are pushing the boundaries of CNC milling and rapid prototyping. A sample: Using devices initially developed for reconstructive breast surgery, designers are creating “skins” for gaming. Downloading U.S. Geographic Service “DEMS” (digital elevation models), web artists are creating interactive sites with unprecedented topographic detail. Using new rapid prototyping systems, digital sculptors are creating tangible, full color objects that bypass the products of traditional model shops. Engineering their own CNC mills they are creating massive sculptures not limited by conventional build envelopes.
Welcome to the world of “extreme 3D art.”
The artist of the 21st century is, out of necessity, a boundary pusher, a cross-disciplinary thinker, and a cultural and technical tinkerer and hybridizer. Artists need to be savvy enough to talk themselves into labs and studios where the really cool equipment is hidden. Or, if necessary, build it themselves. While digital artists working in the 3D arena know their software—be it a solid modeling or animation package—many are out of the loop when it comes to bringing real-world data into their familiar virtual worlds—or, conversely, figuring out ways to push their designs out of the box and back into the real world.
The 21st century artist interested in the power of the third dimension needs to develop expertise in three domains: 3D Data Capture (input technologies); Computer Aided Design, modeling, and visualization (CAD), and Computer-Aided Manufacturing (CAM). While most computer artists are adept at modeling, a primer for 3D Data Capture and computer-aided manufacturing may prove useful.
3D Data Capture
The idea of 3D data capture covers a wide array of systems--from microscopes to satellites. Virtually anything that can be mapped in 3D can be rendered as a digital model.
Consider the following: Extremely tiny objects—blood cells, crystalline structures, and molecules—can be rendered as three-dimensional models using techniques such as scanning probe or atomic force microscopy. Objects are measured in nanometers—units a billionth of a meter long. Slightly cruder in its resolution is the confocal microscope, which is adept at rendering three-dimensional objects in microns—units a millionth of a meter long. While these systems aren’t going to be found at your nearest Fry’s, it may be worth a trip to your local University to see what the engineers or bioscientists are doing with such instruments. They may be able to provide you with data sets that could be integrated into your artwork.
Surface of a CD-ROM captured with an Atomic Force Microscope. Sample is 15 microns across.
At slightly larger scales, objects several millimeters across can be digitized with manual probes or optically scanned using 3D laser scanners. Depending on the lens configuration, resolutions as fine as 0.125 mm can be achieved. Whole body scanners—such as has been developed by Cyberware of Monterey, California—record a million data points spaced at latitudes 3 mm apart.
Camera based systems such as 3Q, Inc.’s are configured to digitally capture the human form in 3-D using a non-laser technique known as digital surface photogrammetry. This approach involves projecting a random light pattern on the subject and capturing the surface contours and color information with precisely synchronized digital cameras set at various angles. Since several of these systems are now located in shopping centers around the country, Gamers can get their “skins” for the price of a good haircut.
3Q digital surfacephotogrammetry originally used for breast analysis
Medical diagnostic technologies such as MRI, CT scanners, and 3D ultrasound give three-dimensional representations of internal morphology. A company called AmeriScan is providing state of the art CT scans in upscale malls for a fraction of the cost of a typical hospital visit (around $900). These technologies enable a new kind of “figurative sculpture” that reveals both internal and external anatomy.
Low cost CT scanning by Ameriscan
Long range scanners from companies like Mensi and Cyra produce high resolution 3D models of larger objects such as architectural facades, geological features, or archaeological sites. Using lasers and optical triangulation, these systems can acquire data up to 100 meters from the source object at accuracies up to 0.21 mm. Sample “point cloud” datasets can be downloaded from the internet and translated into polygonal files using applications such as Polyworks or RaindropGeomagic Studio.
At very large scales, terrestrial maps or extraterrestrial planetary surface data are delivered by satellites capable of measuring not only latitude and longitude but altitude. Satellite data in the form of digital elevation models is freely available from the U.S. Geological Survey. These models consist of a sampled array of elevations for a number of ground positions at regularly spaced intervals. Many of the height maps derived from these systems are encoded as value scale images (where lighter values correspond to higher altitudes). These can be translated into usable 3D models using conventional 3D modeling packages such as Rhinoceros or 3D Studio Max. New York media artist John Klima has used DEMS in his notorious web-based project The Great Game, which, during the recent events in Afghanistan, recorded troop movements in relationship to a 3D terrain map of the region.
The Great Game by John Klima
In sum, there are countless sources for real-world 3D data opening up unlimited possibilities for artists.
At the heart of the process of digital sculpture is the desire to translate three-dimensional objects designed in the virtual space of the computer into actual three-dimensions. Processes ranging from Computer numerically controlled milling, or CNC (a subtractive process), to rapid prototyping (an additive process) can be used for producing tangible prototypes and sculptures.
Advances in the range of materials available for prototyping permit particle sizes of as small as 40 microns (e.g. DTM’s”True Form”) which can be fused for fine feature definitions down to .004 inches resolution. A short list of the companies that manufacture RP devices include the following: 3D Systems pioneered the so-called “stereolithographic” systems (SLA) in which a bath of photosensitive resin is hardened by a laser. Stratasys specializes in a process known as Fused Deposition Modeling which involves the extrusion and precise layup of a continuous thread of hot thermoplastic. They have recently introduced a sophisticated FDM machine for under $30,000. Z-Corp’s technology is built on an MIT patent for “3D printing” which bypasses the need for support structures by building the object in a container of starch-based powder. While it is like other “layered manufacturing processes” in that it utilizes an .stl file format, it uses an “inkjet” type process to harden the layers of powdered starch/cellulose. Z-Corp recently introduced both a full RGB color machine (millions of colors) and a machine with a much larger build envelope (20” x 24” x 16”).
In the recent “Bit Streams” exhibition at the Whitney Museum of America Art, rapid prototyping tools were used by artists Robert Lazzarini and Michael Rees to create stunning sculptures generated from a combination of synthetically modeled data and 3D medical scanning.
Artist/inventor Bill Kreysler has been working for years developing his own CNC machines for scaling up sculptural work. His best known projects include several projects for pop artist Claes Oldenberg as well as the MGM lion in Las Vegas. The lion was first modeled in clay, then digitized using 3D laser scanning. Tool paths generated from this original model were used to cut massive styrofoam blocks. Molds were taken from the scaled up foam model, and a bronze version of the Lion—the second largest bronze sculpture in the world—was eventually produced.
All of these new concepts and systems depend on the computer for its ability to translate quantifiable data into visual information. Using systems that are becoming increasingly accessible to the non-technologist by virtue of improved graphical interfaces and hardware, artists can now move with impunity (if not total freedom) in a domain previously dominated by computer scientists and engineers. We are already seeing hi-res 3D scanners located in malls. Can it be long before we see a “3D Kinkos” that will provide CNC or RP services for the general public? Of course, then it will no longer seem so extreme.