The piezoelectric materials langasite (LGS) and calcium tantalum gallium silicate (CTGS) have been investigated with the X-ray rotation tilt (XRRT) technique using a new evaluation method. The XRRT technique is a microdiffraction method where diffraction lines are registered on a two-dimensional detector. These lines can be described using conic sections analogous to Kossel lines. Their form and position depend upon the lattice parameters and orientation of the investigated crystal. They can, therefore, be used to obtain these parameters. The new evaluation method allows for an automatic indexing of XRRT and Kossel reflections without knowledge of the pattern centre and detector-to-sample distance. This enables the investigation of more complex crystal structures like LGS and CTGS, where in this work the lattice constants and orientation were measured at various points on the sample.