I am using elevation splines hand drawn from viewing a GIS elevation plot for my lot. The Terrain I have drawn is the footprint of our lot and I have one built structure entered that is intended to have the slab floor surface approximately 40 inches below the grade on the north and west sides, sloping to ground level on the east side and at ground level on the North side (like a daylight basement). For some reason I cannot figure out, the area under the building is showing on the 3D image like is is a very deep hole. That causes a steep peak beside the building, probably due to smoothing? Any help with how to resolve is most welcome. with the elevation data, the plan file exceeds the 14Mb size limitation to attach so I have included a dropbox link in my signature hoping that will give you access?