The  number  of  rotary  steps  should  be  between 400 and 1600 per 360° revolution. By using a function for image averaging, several images can be overlaid for each rotary position. Thus, noise can be reduced at the cost of measurement time and the repeatability of the measurement  results  can  be  improved.  The magnification  for  tomography  must  be  selected according to the desired resolution and measurement uncertainty. If required, raster tomography can be used.  The X-ray images are stored during tomography. The 3D volume data is reconstructed in parallel in a step wise progression. After the measurement is completed, the measured point cloud is calculated and provided in STL format. Both the reconstructed volume data and the measured point cloud can then be used for further analysis, or archived for later analysis. The latter is of particular interest with respect to requirements in the sense of product  liability,  because  any  desired analysis.  Analysis of the tomography results generally starts with a comparison of CAD data to the point cloud position and orientation (work piece coordinate system) and subsequent overlaying of both. Various methods are available for this. One method consists of constructing one coordinate system for both the measured points and the CAD model. Geometric elements, such as points, lines, cylinders, or planes, are selected or measured to define the two coordinate systems and are used for the overlay. The result is shown graphically in the software as the overlay of the measured point cloud and the CAD model.  An alternative method is available in the  form of  an  automatic  overlay  function that orients the point cloud to the CAD model using the least square error method. Here again, the measurement point cloud is then overlaid to the CAD model for further measurement data analysis.

Seen : Comparison between measurement point cloud and CAD model: a) CAD model b) Measured point cloud c) Result of the comparison