The comparison of the measured point cloud to CAD or master part data can also be used directly to correct injection molds. To do this, the nominal to actual deviation calculation is performed as a first step. The deviation data are then mirrored around the nominal data set (this  corresponds  to  a change  in  sign  for  each  deviation  value). The data set thus generated can be used as the basis for the correction of the tool, or even to make a new one. The process is shown schematically. The starting point is the 3D CAD data set of the work piece to be manufactured. Using a suitable programming system and considering the technology parameters of the injection molding process, such as material shrinkage; a data set is generated for the injection mold. This can be output and stored either in CAD format or as triangulated data (STL format).  An executable CNC program for a machine tool is then generated from these geometric data by a post processor and the injection mold is directly machined.  Another method is to machine an EDM electrode that is used to produce the actual mold in a die sinking process. After the mold is complete, the first sample part is produced using injection molding to check and correct the mold. This part is then measured using X-ray tomography. A deviation data set is generated from the comparison to the CAD data. Using these data, either the work piece CAD model can be changed or the geometric data of the tool can be modified appropriately. The latter can also be done directly in STL format.  In practice, these processes have to be done only for those mold parts that actually need to be corrected due to their relations to the tolerances.  Using the corrected mold data, the mold is then either reworked or, in the worst case, remade. The work pieces that are then produced are corrected by the deviations captured in this process. In exceptional cases, a second correction loop may be needed to increase precision. It is critical for the process described above that all other technological parameters, such as temperature, plastic material, and other influencing factors are held constant.