Hi everyone. I want to perform viewshed analysis, so on my original DEM I wanted to add the heights of some points(watch towers). I transformed the points to raster, then I reclassified it so the null would become 0 (to have the same dimensions with my original DEM) and then Added them with raster calulator. I checked the new DEM and it was the same as the original with the heights of the points (watch towers) added. The problem is that when i performed the viewshed analysis the visible areas where less than those before !!. what went wrong ?? (before in the viewshed analysis I used the original DEM and the OFFSETA).