3D measurement methods and systems

A set of different methods are available for the acquisition of 3D data.  SINTEF assists the industry in deciding which method to choose in order to solve a particular measurement problem. In some cases it will be adequate to measure two dimensional shape profiles, while in other cases it is necessary to provide complete three-dimensional information. Sometimes measurement time is not a critical issue (such as for off-line shape measurements in the laboratory) but in many cases it is necessary to perform the measurements within a few seconds (e.g. for in-line product inspection in factory lines) or even in a fraction of a second (such as for autonomous navigation based on real-time 3D imaging of the surroundings.)

Some of the 3D shape measurement systems that are in use at SINTEF include:

• Structured light systems (also known as fringe projection systems)
• Time-of-flight cameras
• Laser scanners and laser triangulation systems
• Stereo vision
• White light interferometry

SINTEF has developed its own, low cost 3D camera based on structured light suitable for product inspection and shape measurement in general. For more information, see our structured light webpage.

3D analysis and interpretation

SINTEF assists its customers in the development of sophisticated data analysis algorithms for 3D data, in order to semi- or fully automatically determine e.g.:

• Geometric properties of objects (e.g. sizes, distances, angles, cross sections etc.) 
• Deviations between a produced product and its CAD model (for quality control)
• The position and pose of objects (e.g. to pick and place objects with a robot)
• Interpretation of a scene (e.g. to enable autonomous robot interaction and navigation)

We have a growing set of algorithms ready for use, but the algorithms typically need to be adapted to each individual problem. By using detailed knowledge about the physics of the imaging sensor, the imaging situation and the characteristics of the 3D scene, we try to ensure that an optimal performance is achieved.

Applications

Some important applications for 3D measurements and analysis at SINTEF are:

• Product Inspection (in-line or off-line)
  Optical systems provides a fast, relatively low cost and non-contact solution for measuring the 3D shape of products. This makes them suitable for a wide range of industrial applications, such as in-line quality control in production lines.
• Robot Picking
  3D imaging allows the position and pose of objects to be estimated with six degrees of freedom. This information can be used to pick and place objects with a robot.
• Robot Navigation
  Emerging new technology, such as time-of-flight cameras, can be used to equip robots with real-time 3D vision. This allows them to see and interpret their environment in three dimensions, to navigate and to make decisions.
• Other applications of 3D shape measurement systems
  SINTEF has utilised 3D shape masurement technology in a number of projects that do not fit into the categories above, such as for 3D digitization of petroglyps and cultural heritage and as a guide for navigating surgical instruments inside the body during non-invasive surgery.