Several things you can do, none of them particularly great, since P4 doesn't support collision detection... Use a magnet to flatten the hair at that point. Make a custom transmap to make the poking through part of the hair invisible. Resize and/or reposition the hat.

I should have mentioned that I have P5, and I switched on collision detection for both hair and hat, not really knowing whether it would work or not....did'nt seem to.

Hmmm. Not having P5, I couldn't be sure, but I think collision detection only works on dynamic stuff.

From my reading of other posts I think collisions detection tells you when static objects are in contact, but doesn't do anything to adjust them. Select the hair, then Object>Create magnet. Move and scale the Mag zone prop so that it just encloses the projecting bits of hair, then select the Mag prop and try a combination of -z/-y translation and scale reduction to suck the hair out of sight.

Or if you have a graphics editor (Photoshop, etc.) you can do two renders - one with hair and hat, and one with just hat and no hair. Then in graphics, take the bit of the render with no hair and paste it on top of the same area in the render with the hair. Now you've got just the hat and the hair flowing underneath.

Hmm. Thanks all for your contribution, there are numerous workarounds - none of which are ideal. Sounds like the easiest way out is to doctor the transmap, so that that part of her hair simply doesn't exist. Using magnets sounds rather terrifying, from my previous experience with magnets it is not going to be easy doing it that way.....

addendum to my post: If one is an experienced Photoshop user - you can simply put the 2 renders on separate layers and then erase through the "hair and hat" one to the "just the hat" one.

mathman, now may be the right time to bite the bullet and learn about magnets. :) I'm by no means an expert but I'm more comfortable than I used to be, just from spending a day playing around with them.

The two renders would be the way I would do it. One with the hat, that will give the shadows. The other with just the hat, everything else deleted, on a black background, saved as Tiff or Psd for alfa channels. Layer the hat on the original render. Magnets will have to be perfect, so as not to mess the hair below the hat. I have done this with good results, just not as good as the layer rendering.

Attached Link: http://www.morphworld30.com/

For those not wanting/willing/unable to learn the magnet method, I think using the two (or more, how ever many is needed) renders, then either layering & erasing or cut/paste/erase method is the best thing - lord knows it's what I do. :)