This is a phase (intended only for stereometric shots) which aims to verify:
- the legibility of the photographic images and, therefore, the acquisition of the requested information;
- the recording of the frames determining the internal orientation;
- data relating to external orientation;
- the survey of the control points.
In the case of the stereometric chamber, the verification of the relief of the control points is replaced by the calibration of the stereocamera itself. The operations listed above assume that, in the shooting phase, the framing of the object has been taken care of from both points of view and that, therefore, the stereo vision cannot be disturbed by the presence of harmful close-ups.