Extensive Testing and Comparison of a New Type of Target for Use in Engineering Surveying

The paper deals with the testing of a special target for determining the exact dimensions of steel structures and their descriptions. In most cases, the accuracy required in mechanical engineering is on the order of millimetres, and the location of a point on a steel construction is marked by a centre punch. Due to the segmentation of steel constructions and the impossibility of the vertical placement of a target, it is very difficult to use ordinary prisms because of their size and the linear error from a wrong rotation and a nontrivial conversion of the centre of a prism into a centre punch on a steel construction. For a more accurate determination of spatial coordinates, a special reflective target with a reflective foil and a mechanical collimator, which ensures the correct angle to the target device according to the instructions of the person at the instrument, has been developed. Centration with a high degree of accuracy is achieved by a spike. Its functionality and usability goals have been tested and compared with standard methods of measurements and goals in engineering structures.