I have been trying to generate an elevation model from contour lines using first v.to.rast.attr and then r.surf.contour. Generally, it works pretty well, execpt for one issue. My data contains a lot of sea without contours, and r.surf.contour spends a lot of time in the sea region where there are no pixels in the raster generated from r.to.rast.attr. Actually, I'm running one now on a reasobly large area, and after 24 hours, it is at 70%.
The solution for me would be simple. I have sea polygons (and even lake polygons with elevation). I could generate a separatr raster for that using v.to.rast.attr.
But then I need to combine the two rasters into a single raster before running r.surf.contour.
How do I do that?