How to interpolate an elevation raster from vector data set?

Hello Grass user,

  I digitized a topographic map (scale 1:25000) to get a vector
  data set with contours, representing the elevation.

  How to interpolate the vector data set to generate a raster
  data set representing the elevation information?

ciao

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Dipl. Geol. Andreas Holz email: asholz@cip.informatik.uni-erlangen.de
Institut fuer Geologie und Mineralogie
Schlossgarten 5
91054 Erlangen
GERMANY