While hand-craftsmanship still has its place, if you need 100 identical pieces there is a strong case for applying new technology—and it doesn’t have to be costly or difficult to use. The key is understanding where the technology can be applied appropriately and identifying the right people to help you. The cost of the software to do these reproductions is high, but you can outsource this step to an outside designer, which will still save you money and time. Here are two high-tech methods I’ve recently used.
I needed to match a set of hand-cut roof strut details and reproduce a set of five identical pieces. A computerized drawing would make it easy to adjust scale, make changes to the shape and curvature, and quickly explore new shapes and profiles before cutting.
All I needed were two good-quality photographs taken from different angles. By using two photos, any standard PC with EOS Systems’ PhotoModeler software can extract three-dimensional information about the shape. The process is called photogrammetry, which uses two images of the same target taken from different positions to mathematically calculate the distance to the target.
These don’t have to be digital images, either. You could even use stereo vision image pairs of public buildings and historical sites captured for use in the stereo viewers that were popular at the end of the 19th century.
The photos are then processed using PhotoModeler, which finds features common to each photograph, automatically matches them up, and uses them to calculate the distance from the camera. The process corrects for lens distortions and reproduces the shape in 3-D.
The 3-D model then can be imported into a 3-D CAD package and positioned perfectly flat so a true profile can be traced. Using standard 2-D CAD drawing tools, trace the profile into a new 2-D CAD drawing suitable for cutting with a CNC (computer numerical control) router, which uses a high-speed spinning cutter much like the hand-held router that most builders are familiar with.
Why 3-D to 2-D? With just a single photo, there’s a good chance that the image will be distorted. By capturing everything in 3-D, you can orient and trace the item in the computer and counter the effects of lens distortion and perspective.
Once the 2-D CAD drawing is complete and fit to the final design, you can take it along with the raw material to a fabricator with a CNC router who can fabricate any number of identical finished pieces quickly, accurately, and with a faithful nod to the original builder.
I found 3-D scanning a fast and cost-effective way to get a hand-carved detail to cover an entire length of a fireplace mantle.
Unlike the prior example, this time I brought a hand-carved sample to the 3D Scancraft office in Portland, Ore. 3D Scancraft provides digital 3-D solutions for mechanical, art, and architectural reproduction and preservation. (If you’re not in Portland and lack a similar service provider in your area, you can ship items to Scancraft for reproduction.)
3D Scancraft president Daniel Ferguson and his team used a High Definition Imaging (HDI) Flexscan Advance 3-D scanner—a white-light 3-D scanner—from 3D3 Solutions, and captured the scan. They copied the single scan and duplicated it to form a continuous repeating pattern that could then be cut to the 84-inch installed length. The installation also called for two more repeated details in 24-inch lengths so we used the same pattern for the shorter lengths as well.
3D Scancraft then cleaned up the digitized pattern using special computer sculpting tools designed specifically to work with 3-D scan data, in this instance, ZBrush software from Pixologic. With the computer, it was easy to make adjustments to the final shape and ensure everything blended seamlessly over the entire length of the shape.
Working with a digital 3-D model is much faster and more forgiving than working with real stone. The computer offers an array of digital carving tools familiar to any traditional sculptor, as well new features such as “rescaling” and the “undo” command, which are only possible with a digital model.
Once satisfied with the digital model, we sent the file to a local CNC router to cut a prototype in high-density foam. The foam cuts quickly and easily and allows you to see how the final shape will appear after it’s cut. This step is important—especially when working with expensive or hard-to-cut materials. The final shape may differ slightly from the 3-D computer model, due to the shape of the cutting tip and the controlled path of the machine. Detailed shapes such as this may have slightly less detail than their finished counterpart, and it’s worth the extra cost to have something in your hands quickly so adjustments can be made early on.
Once the final finish was approved, we sent the same pattern to a specialty stone carver who was able to reproduce the entire carved mantle with exceptional precision and detail in just a few days.
The greatest danger in reproducing an object from a photo is parallax correction. Parallax is the result of viewing an object from one perspective, which creates distortions. While your eyes and brain can largely correct for this through the stereoscopic nature of your two eyes, a camera cannot. But as shown here, with multiple photos and the right software, a true 2-D drawing can be generated.
When not corrected, however, parallax can cause unintentional problems. The existence of parallax and the brain’s desire to find it is why drawings using the vanishing point are so realistic and pleasing. In other words, we see parallax all around us all day, and introducing it into a drawing can make it “come to life.” Artists have exploited this trick for centuries.
Here are two more ways to do fine precision cutting other than the CNC router mentioned in this article. Lasers offer a cost-effective way of reproducing profiles in flat metals. The most common commercial laser cutters are set up to cut thin plastic, steel, aluminum, or any material that will melt in response to intense heat. Lasers can cut paper and wood material in some applications, but will leave a charred edge where the laser makes the cut and may not be suitable in all applications. Water-jet cutting is versatile and works well with common architectural materials. The water jet uses a high-pressure jet of water and abrasive grit to blast through nearly any material.
—Clint Howes is a remodeler in Portland. Ore., who is always seeking to connect the past to the future. Daniel Ferguson is president of 3D Scancraft, in Portland, Ore. He performed the digital services for the examples used in this article.