Two ways to capture a shape
Measuring a three-dimensional object means recording where its surface is in space. Early methods fell into two families: touching the surface and not touching it. Touch probes were developed first in metrology laboratories and workshops. Optical methods, especially laser triangulation, followed as lasers, cameras and computers became affordable enough to use outside a research lab. Most commercial 3D scanners are descended from one or both.
Touching the surface
A coordinate measuring machine, or CMM, moves a probe to points on a part and records the position of each along three axes. Machines of this type were developed in the middle of the twentieth century, with British firms such as Ferranti often mentioned among the early builders, though the precise sequence of who built what is difficult to establish.
A key improvement was the touch-trigger probe. It sends a signal the moment its tip makes contact, so the machine records the position at that instant, with no guesswork about how hard the probe is pressing. David McMurtry, working at Rolls-Royce in the early 1970s on the problem of measuring complex engine parts, is usually credited with the design. His work led to the founding of the company Renishaw in 1973.
Touch probing is accurate but slow, because each point is collected one at a time. To capture a freeform surface such as a car body or a sculpted part, an operator had to choose points carefully. The method also cannot be used on soft, fragile or hot objects without risk of altering them.
Light instead of touch
Optical measurement avoids contact. In laser triangulation, a laser projects a dot or a thin line onto the surface, and a camera, offset by a known distance and angle, views where the light lands. If the surface is closer or farther, the spot shifts in the camera image. Because the laser, the camera and the spot form a triangle with one known side and two known angles, simple trigonometry gives the distance.
A single dot gives one measurement at a time. A line gives a full profile across the object in one instant, and moving the object or the scanner produces many profiles that, joined together, describe the whole surface. This is the approach behind many handheld and desktop scanners today.
The precision comes with caveats. Shiny, transparent or very dark surfaces can confuse the camera, deep recesses may be hidden from the line of sight, and the scanner must be calibrated to know the exact geometry between laser and camera.
Laboratories and early systems
Research groups in several countries worked on range sensing in the 1970s and 1980s. Canada’s National Research Council is often cited for its work on laser-based range sensors and their use for recording objects and artwork. Meanwhile, companies appeared that built scanners for particular jobs. Cyberware, founded in California around 1980, became known for scanners that captured the human head and body and were used in animation and film production. Such details are usually drawn from company histories, so dates should be treated as approximate.
Other measuring principles developed alongside triangulation:
- Time-of-flight, which measures how long a laser pulse takes to reach a surface and return, suited to buildings and landscapes.
- Structured light, which projects a pattern such as stripes and calculates shape from how the pattern bends.
- Photogrammetry, which reconstructs shape from many ordinary photographs.
Each has strengths: triangulation excels at short range and fine detail, time-of-flight at long range, and photogrammetry at low equipment cost.
From lab bench to catalog
Three developments moved scanners from experiment to product. First, solid-state lasers and digital cameras replaced larger and costlier parts. Second, computers became fast enough to process millions of points; sensors built on silicon chips supplied the images, and software turned them into usable meshes. Third, demand arrived from several industries, including automotive design, reverse engineering of existing parts, film and games, and quality control in manufacturing.
Commercial systems of the 1990s often took the form of a laser head on an articulated arm or a rotating stage. Later, handheld devices tracked their own position and removed the need for a fixed setup. The result was a gradual drop in cost and size, though high-end metrology scanners remain expensive.
How scanning connects to printing
Scanning and printing grew up as complementary technologies. A scanner can capture an existing object and a printer can reproduce or modify it, and scanning is used to check printed parts against their designs. That relationship helped scanning find a market beyond traditional measuring labs.
What is well established
The broad outline is firm: contact probes came first, optical triangulation followed, and commercial scanners appeared from about the 1980s onward. What is less certain is attribution. Many people worked on range sensing in parallel, and claims of “the first 3D scanner” depend on how a scanner is defined.