Huge human head in a world you can walk on.

#1 Five minutes to walk from one side to the other (assuming default walk/run speed) is bigger than one entire non-repeatable terrain block (without tweaking the terrain scale) so that is definitely massive.

My first thought to implement such a large structure would be to split it into smaller sections and place it as multiple interior (.dif) files. At a scale that large much of the surface area would appear to be fairly featureless and flat so most of these pieces wouldn't be very complicated structures. You'd then benefit from implementing LOD per section too.

Of course you'd have to deal with the limitations of the interior format which will make creating details a bit tricky, but making a .dts shape that large might give you collision problems. You could also create the basic head shape in sectional .dif interiors (or heck even by shaping the terrain if you only need one half the head) and add the features as .dts shapes. You'd have to experiment though, since (for example) a head that takes five minutes to walk across means an ear that is at least a one minute walk from end to end; still a pretty big shape to be implementing as a .dts.

#2 Well 5 mins might be much to big lets say I make it a 1 min walk from end to end. If I did that could I use a dts shape. Because I want to have the head facing the sky so when you walk to a certain point you will fall off the edge. I'm not going to have it all be the same group so It shouldn't heve collision probs. It won't have a back etheir.

#3 I just did a few tests with some simple static shapes, and certainly you wouldn't want this to be all one shape. There appear to be many problems with having one humongous .dts, not the least of which is there seems to be distance culling based on the center of the object. At the edges of a very large shape the shape simply disappears. You could potentially modify the source to fix this issue, but there are others to deal with too. It would be difficult if not impossible to implement proper collision for all the smaller features of the head this way since a single .dts shape has limitations on the number and complexity of collision geometry. This is another benefit of using .dif files where every brush is independently collision-tested.

One minute travel time is between 1/3 and 1/2 the distance across of a default-scaled terrain block, so this is a more reasonable goal and I think doable if you use the right combination of sectioned .dif's and dts accent shapes.

Another alternative to investigate is to make the head normal (or perhaps slightly larger than normal) sized, and make your characters much smaller, scaling their size, movement speed, etc. This will probably present its own problems but it is probably worth looking into.

#4 Do you think it's posible to make the head a little bigger that normal and make the player very very small.

#5 There might still be some issues with velocities, collision-detection, etc. so it might be something to just try and see how well it works. I don't know of any major reasons why it shouldn't work though (perhaps someone else has tried this already and can comment though.)

#6 If you are talking face towards the sky why not make the terrain itself shaped like a head, and scale down the player to say 0.5 0.5 0.5 to make it seem even larger? I'm not sure exactly how to create the heightmap for the head, but I've got to imagine it's possible.

#7 And now for something completely different...