If fragments taken from different perspectives are compared, one can see than accuracy decreases due to matching errors. In the same time there are the following matching technologies:
- Matching by geometric features of an object. This is the most accurate technology provided that there are enough geometric features on the object. Accuracy at such matching decreases a little, if the object doesn’t get in the scanning area completely. If geometric features are few, for instance, when scanning smooth fragments of a car, it is necessary to use matching by markers.
- Matching by markers. Markers are being attached to an object before scanning (white round pieces on a black background). Their coordinates are being calculated by the scanner automatically and used for fragment matching. When scanning big and lengthy objects, errors of marker coordinate determination are being accumulated. Such objects should be scanned by means of photogrammetry. Markers should be stuck on correctly, i.e. chaotically and evenly over the whole surface as possible and not creating rows or lines.
- Matching by markers through using a photogrammetric system. In this case matching is also done by markers, but markers’ coordinates are being identified by a photogrammetric system beforehand and with high accuracy. This allows to minimize accuracy loss, when matching big or lengthy objects.