[R-sig-Geo] Distance from point to specified raster cell value

[Alexandre Lafontaine]

Dear members,
I am looking for a way to extract the distance from spatial points objects to the closest raster cell of a specific value. I have not a found a way to do so yet with the raster or rgeos librairies...

Something like the gDistance function in which I could specify the raster value I am interested in:


         gDistance( spatialpoints, r[r==15])


If anyone have suggestions, (it needs to be fairly quick because I have thousands of points to compute).


Any help really appreciated,


Alex Lafontaine