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Data can be transformed to comply with new spatial data following the orginal data capture. Usually these are limited to Affine, Helmert and Projective type transformations.

The following table summaries the types of distortion and the methods that may best suit the original data set. It should be noted that even after the transformation there may still be distortions, however the mathematical models of each transformation type are designed to minimise distortion.

"Transformation Type                                         Affine                    Helmert                    Projective
Equal X, Y scales                                                                                 X
Different X and Y scales                                         X                                                            X
General axis rotation                                             X                            X                              X
Skewed co-ordinate axis                                        X                                                            X
General XY origin translation                                 X                            X                              X
Varying localised scaling along X and Y axis                                                                          X    "

Abakos Digital Images

If you are using Microstation the Abakos Digital Images Transformation Utility is and excellent tool.

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Last modified: February 20, 2001