Why does "within distance" work with characters not scenery ground?

[PHD2B]

When I set Alice to detect distance to e.g. a toadstool character, my events all work, however when I try to detect distance to ground (grass world) or scene ground, it does not work? Obviosly I am attempting to keep the character above the ground and am having no luck. Everything else is great but I see no reason to continue with this game until I have this figured out.

Please advise.

[Chris101b]

I might know what the problem is. In Alice, when you are talking about distances between something you are not talking about the distance between the two objects, but rather the distance between the exact center of two objects. For example, if you have 2 spheres and you tell the program that when the spheres are within 0 meters of each other, you want something to happen. This means that if the two spheres touch, nothing will happen, the EXACT center of the first sphere has to touch the EXACT center of the other one. This is going to be the same with your world. If you tell the program that you want something to happen when you are 5 meters away from the ground, nothing will probably happen, because you have to be 5 meters away from the center of the ground (very middle of the map). You can also use the whole "Distance above" and "Distance below" options in the functions menu.

[PHD2B]

Based upon the way it was reacting that makes perfect sense. How do I use the above and below functions? The "threshold" and "within" functions are the only ones that will accept above and below.

Thanks for your help

Jeff