So I'm struggling here, trying to get a decent DEM for the Azores Islands because I want to include bathymetric data on it.
I have a raster with elevation for the islands (land) with a 30 meter resolution, which is actually more detail than I would ask for but, unfortunately, the bathymetry I have managed to acquire are vector points 3000 meters apart.
I converted the raster into contour lines and tried to make an interpolation using both elements (points and lines), needless to say I run into problems around sea level.
My best results were obtained using a spline interpolation with different smoothing for lines and points on GRASS, but I get artifacts whenever the distance between a vector and a line is close to 3000 meters.
Any tips on how to get a decent DEM when using data of different types and with such different resolutions?