What is the meaning of rotating thorn in aerial triangulation?

In aerial triangulation, it refers to an instrument that punches selected image points on emulsion or punches image points from one photo to another with high precision under stereoscopic observation. The structure of the stereoscopic puncture instrument is similar to that of the stereoscopic coordinate measuring instrument, but it is a precise automatic puncture device without precise guide rails and measuring tools.

Point-to-point instrument, the full name of which is stereo point-to-point instrument, is an instrument that turns the field control points on the indoor measurement images in various ways or marks the encrypted control points and other control points selected by the indoor industry on the same name image points of the stereo image pair under the condition of stereo observation. It mainly consists of a high-power observation system and a needle (or laser needle).

When the three-dimensional target is aimed at the model point, the pricker (or laser pricker) pricks holes in the photo. This plays an important role in improving the accuracy of analytical aerial triangulation.