TRANSFORMATION OF MAP INFORMATION FROM ONE DATUM TO ANOTHER

K. Engsager

Danish National Space Center, Geidetic Dep., Copenhagen, Denmark

null@monomax.org

The process of transforming the scanned coordinates of an old Sea chart to a new datum realised through orthophotos is described in details: from pixel coordinates to geographical coordinates, collocational interpolation griding of differences to coordinates in the new datum. A discussion of tools for this kind of transformation of ‘non-conformal’ projection data to a conformal realisation of a datum. The term ‘non-conformal’ means: Originally the old coordinate system is realised as a conformal coordinate system, - but compared to a new realisation of higher accuracy the old one is definitely not conformal.