I've created a DEM from LiDAR data. After combining all the files, I could see that there are some problems through the tile borders. This is an screen focused in one of the cross section of 4 files connected.
All the values are around 800m, while the "black lines" contain values around 400. I'm looking for a raster tool where those values can be interpolated.
Here is the peace of raster (.tif, epsg:25829) to try by yourself. https://drive.google.com/open?id=18LgIp6VNyCphDpnRVPlZelLFd3m8JF4y