Active triangulation is the most fundamental and widely used 3D measurement principle in intraoral scanners. Structured light and laser line scanning technologies are essentially variants of triangulation.
Basic Principle
Triangulation originates from the classic trigonometric ranging method. The system consists of a light source (projector or laser) and a camera separated by a known fixed distance (baseline length bbb) and angle. The light source projects a known pattern (fringes, spots, or a laser line) onto the object. The camera captures the pattern from a different viewpoint. Depth variations on the object surface cause the pattern to shift in the camera image (parallax). Using the principle of similar triangles, the depth Z of each point can be calculated from the known baseline, projection angle, and imaging position.
A simplified depth formula is:
Z=(b * f) / d
where bbb is the baseline length, fff is the camera focal length, and ddd is the parallax displacement. A longer baseline improves accuracy but increases device size. Fitting both the projection and imaging systems into the extremely compact scanning tip of an intraoral scanner remains a significant miniaturization engineering challenge.
Structured Light Triangulation
A sinusoidal fringe or Gray-code pattern is projected. A single image captures depth information across the entire field of view, delivering high speed and dense point clouds. Representative brands include 3Shape, Shining 3D, and Aident.
Laser Line Scanning Triangulation
A single laser line is projected. The camera records the deformation of the line on the tooth surface. Three-dimensional data is acquired line by line by moving the laser or the scanning head. Representative systems include Planmeca (blue light) and early E4D systems (red light).
Factors Affecting Triangulation Accuracy
Baseline length: Longer baselines improve precision but are constrained by scanning-tip size.
Angular resolution: Determined by camera resolution and lens quality.
Sub-pixel algorithms: Feature localization can reach one-tenth of a pixel.
Surface optical properties: Translucent or highly reflective surfaces interfere with pattern recognition.
Ambient light interference: Stray light reduces the signal-to-noise ratio.
Active triangulation is mature, cost-controllable, and offers excellent real-time performance. It is the foundational principle adopted by the vast majority of current intraoral scanners. Its main limitations are sensitivity to surface optical characteristics and the accumulation of errors during large-field-of-view stitching.
At Aident Technology, the AI-30 intraoral scanner series is built on advanced structured-light triangulation combined with high-speed imaging and intelligent processing. It delivers ≥30 frames per second, ≤10 μm full-arch accuracy, powder-free true-color scanning, and reliable real-time 3D reconstruction-engineered for efficient clinical and laboratory digital workflows.
Explore our intraoral scanner solutions:
Contact Aident for OEM/ODM collaboration, wholesale pricing, or a live demonstration and experience how precise active triangulation translates into accurate, efficient digital impressions.
