VDI/VDE 2634 BLATT 2
Optical 3-D measuring systems - Optical systems based on area scanning
|Publication Date:||1 August 2012|
|ICS Code (Linear and angular measurements in general):||17.040.01|
This guideline applies to optical 3-D measuring systems based on area scanning, whose function is based on triangulation. The equipment can be configured by the user to suit a particular measurement task. Their sensors consist of several components such as one or several imaging sensors (cameras) and one or several projection systems projecting structures onto the object surface to be measured, or a system serving to illuminate any existing surface texture. Examples of such sensors are measuring systems based on fringeprojection or moiré techniques, and photogrammetric or scanning systems with area-based measuring capabilities.
This guideline applies to the measuring of threedimensional objects in a single elementary measuring process ("single view"). The components of the sensor shall not change their positions relative to each other during the elementary measuring process. This guideline does not cover systems where several single views are transformed into an object-related reference frame by repositioning the sensor and/or the object, for example by means of
• measuring translatory and/or rotary positioning axes
• externally measured reference marks
• arithmetical fitting of the single view into the overall point cloud (matching)
This guideline describes methods and artefacts for the testing of optical 3-D measuring systems. The methods are equally suited for
• the acceptance of optical 3-D measuring systems and
• the reverification of optical 3-D measuring systems (for the purpose of checking of test equipment as specified in DIN EN ISO 9000 through DIN EN ISO 9004)
The requirements to be met by the artefacts used for acceptance and reverification are specified, and examples of artefacts are described. For the purpose of this guideline, an artefact is a linear, two-dimensional, or three-dimensional arrangement of features to be probed. Examples are planes and spheres that can be probed optically. Artefacts shall be calibrated with respect to their dimensions and form.
Quality parameters are defined in order to assess the accuracy
of the measuring systems. Limits for these quality parameters are
specified for the acceptance of the optical 3-D measuring systems
and for their reverification by the manufacturer and by the user,
respectively. All three quality parameters together allow to
quantitatively evaluate the measuring system. Different system- and
The quality parameters serve to specify optical 3-D measuring systems, and to compare different measuring systems. For their values being dependent on the operating mode and operating conditions, it is recommended to define and specify particular operating modes and operating conditions for acceptance and reverification to ensure comparability of the test results. The same quality parameters cannot per se be used for any arbitrary measurement task.
Where no limitations to the operating modes and operating conditions are specified, the specified limits of the quality parameters must be complied with under all possible operating modes and operating conditions. Exceeding the limits of the quality parameters is possible, and permissible, where specified limitations are not met.
The term operating modes denotes adjustment and configuration options of the optical 3-D measuring system such as:
• type and intensity of illumination
• measuring volume
• type, number, and arrangement of the optical sensors used
• type and duration of image acquisition and processing
The term conditions of operation denotes external influences on the optical 3-D measuring system. These include, for example:
• temperature and its gradient
• vibrations (mechanical)
• electromagnetic interference
• environmental lighting conditions