distmap

Dear sig-geos,

I have to calculate a distmap (that is, a map
in which the value of each cell is the distance
from the cell to a given object) for a set of polygons.
It seems to me that distmap.owin in spatstat would do it
fine, but distmap.owin does not accept objects
imported from shp vectors via readOGR. distmap.owin requires
type "polygonal" and readOGR yields class 'SpatialPolygonsDataFrame'
Is there any way to cast or convert from 'SpatialPolygonsDataFrame'
to "polygonal" or an alternative function to calculate the distances
to the boundaries of the polygons?

Thanks

Agus

Dr. Agustin Lobo
Institut de Ciencies de la Terra "Jaume Almera" (CSIC)
LLuis Sole Sabaris s/n
08028 Barcelona
Spain
Tel. 34 934095410
Fax. 34 934110012
email: Agustin.Lobo at ija.csic.es
http://www.ija.csic.es/gt/obster