TS2012 - I'm ready to pull my hair out, if I had some left. I am trying to build a layout using the methods in the video from Hminky. I have the room, baseboard, and walls. I want to dig some holes, and then cover them with a spine surface followed by changing the height of the spline to achieve the floor look that Hminky does. I am unable to get the floor surface (spline surface) to drop no matter what I do. The floor (spline surface) stays at the same height as the baseboard. I have watched the video several times, varied the order of the steps involved, and had a stiff drink - I still can't get it to work. Is there a printed tutorial somewhere that I can't find, despite much searching? I must be missing something.
Make sure you are on the scenery items and splines tab. Click on the advanced pull-out (down?) and type in a minus value. You can then apply that value to the spline circles and that should drop the splines to the "floor".