2DTraC: An Excel add-in for 2D spatial transformations with applications in microscopy and microanalysis

A Microsoft Excel add-in has been developed to aid the relocation of analysis points on petrographical samples between analytical runs on different microscopes and instruments. The general procedure is as follows. Two readily identifiable reference points are defined on the sample. During the first analytical run, the positions of these reference points and of any features of interest are recorded using the co-ordinate system of this instrument. During a subsequent run, which may be on a different instrument with a different co-ordinate system, the positions of the reference points are recorded. The add-in then uses the reference point positions to calculate a set of transformations that maps the co-ordinate system of the first instrument into that of the second. These transformations are then applied to the co-ordinates of the features of interest to calculate their expected positions on the second instrument.