**WHICH ACCURACY DO WE NEED IN GIS**

K. Engsager

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

*ke@spacecenter.dk*

Map
projections are discussed in relation to the accuracy that the users need and
their expectation.

A short
presentation of the transformation of an old map to a new datum is given. Some
big errors appeared and the tracing of the errors is described.

The
accuracy of the projection formulas is discussed in relation to the complexity
of the formulas versus the difficulty of using and performing the calculations.