Dr Thomas Knudsen, National Survey and Cadastre
Dr Simon Kokkendorff
Dr. Karsten Engsager
Dr. Karsten Bormann
KMSTR, the transformation system of the Danish National Survey and Cadastre (KMS), has served as the official tool for transformation between Danish map projections and horizontal and vertical datums for half a century. The system originated as a fairly simple implementation of a few conformal mappings, using one of the first compilers for the Algol-60 language. But it has evolved dramatically since then and survived through a range of three programming languages (Algol, Fortran, C), and a large number of operating systems and machine architectures.
Today, in addition to a large number of map projections, KMSTR supports a range of datum shift operations, implemented using either Molodensky transforms, high order polynomials, or NADCON style grid interpolations. KMSTR also includes support for time varying transformations based on plate tectonic motion models, for deriving the proper transformation between a global datum (e.g. ITRF89) and regional, plate fixed reference systems (such as ETRS89) at different epochs.
Recently the extended transverse mercator implementation of KMSTR was included in proj, the leading open source projection package. This is the first step towards making KMSTR more interoperable with other open source projection and transformation packages. From a KMSTR point of view this is highly desirable, since closer relations to proj and other open source projects will facilitate maintenance and development of KMSTR, and will help keeping it in line with the state of the art in geospatial software.
Thomas Knudsen, PhD, is a geodesist and senior adviser at the Danish National Survey and Cadastre, where his primary focus is on geodetic software tools.