scope:

This guideline applies to mobile, flexible optical 3D measuring systems with one or several imaging probes (such as cameras), whose function relies on triangulation (such as photogrammetry). The equipment can be configured by the user to suit a particular measurement task. The workpiece is measured by tactile or optical probing. In both cases, the quantity to be measured is recorded optically by analysing the images of discrete features of the workpiece, or of auxiliary equipment (measuring adapters). Such features are represented, e.g., in the form of circular reflecting measurement marks or light-emitting diodes (LEDs).

This Part 1 of VDI/VDE 2634 describes methods and artefacts for the testing of optical 3D measuring systems with point-by-point probing. The methods are equally suited for

• the acceptance of optical 3D measuring systems

• the reverification of optical 3D measuring systems (for the purpose of checking of test equipment as specified in DIN ISO 9000 through DIN 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 optically extractable edge intersections, circles, or spheres and surfaces that can be probed mechanically. Artefacts must be calibrated with respect to their dimensions and shape.

A quality parameter is defined in order to validate assess the accuracy of the measuring systems. The permissible limits for this quality parameter is specified by the manufacturer for the acceptance test of the measuring system, and by the user for the reverification, respectively.

The quality parameter serves to specify optical 3D measuring systems and to compare different measuring systems. For its value being dependent on the operating mode and operating conditions, it is recommended to select and specify particular operating modes and operating conditions for acceptance and reverification in order to ensure comparability of the test results. The same quality parameter cannot per se be used for any arbitraty measurement task.

Where no limitations to the operating modes and operating conditions are specified, the specified limit of the quality parameter must be complied with under all possible operating modes and operating conditions. Exceeding the limit value of the quality parameter is possible, and permissible, where specified limitations are not meetmet.

The term operating modes denotes adjustment and configuration options of the instrument 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 evaluationprocessing;

• type, number and form of features to be analysed

The term conditions of operation denotes external influences on the optical 3D measuring system. These include, for example:

• the temperature and its gradient

• humidity

• vibrations (mechanical)

• electromagnetic interference

• environmental lighting conditions

• dust