**THE LENGTH OF COASTLINE OF THE ISLAND OF RAB**

D. Tutic, M. Lapaine, N. Vucetic

*Faculty of Geodesy, Chair of Geoinformation, Zagreb, Croatia*

*dtutic@geof.hr*

The paper gives an overview of the measurements of the length
of coastline of the Island of Rab in the Adriatic Sea from maps at scales 1:25
000, 1:50 000, 1:100 000, 1:200 000, 1:300 000, 1:500 000 and 1:1 000 000. All
maps were or still are the official topographic maps produced by the same
institution. Maps in smaller scale were derived by manual cartographic
generalization from maps in larger scale. An elimination of deformations of map
projections was performed. An estimation of the accuracy of measurements is
given. The results of the approximation of the measured data by methods
proposed by Volkov N. M. and Hakanson L. are given in order to predict the
length of the coastline at larger and smaller map scales. Since new official
datasets are available at larger map scales, predicted lengths by these two
methods were compared with lengths obtained from real data. The predicted
lengths were too short compared to lengths from real data and thus not
satisfactory. A new approximation method by a logarithmic function is proposed
which gives significantly better results. The results show that only moderate extrapolation
of data is of use.