No, sorry Marc, that ain't it.
And welcome Outback, glad to see you can post okay.
Fact is, the water "box" (it's just a plain ordinary box prim.) can be
textured with just 'pigment {rgbf 0.75}' and the effect can show itself.  Also
likewise for the isosurface, removing all other texturing still causes the
border line.
I had put the camera at the water surface (top of box) to check for the
mysterious gap and none is actually there.  Good suggestion though Marc, nice
to know you're thinking.
Far as the negative/positive noise goes I can't see why that would change
anything about this really.  It doesn't appear to be a real cutaway or
anything, just that it shows up with the box present and having a filtered
pigment so you can see below the box surface.
Attached another image having camera near but below the top of the box
instead.  My guess is it's some sort of precision error with object
intersection (no CSG done though. Hey! I'll try 'union' then...).  The scales
of this scene are on the small side, not too small I'd think though.  Entire
thing is encompassed by a sphere for the sky at 30 units radius, camera is
about 2 units from <0,0,0>.
Thanks for any further insights or ideas.  I'll be checking further anyhow
putting + and - in the island isosurface per Outback's suggestion though I
hold no hope for it just now.

Bob

"Outback" <out### [at] huntelnet> wrote in message
news:393edb29$1@news.povray.org...
| I remember reading somewhere in the ~ 40,000 messages here or
| in an isosurface tute that:  noise and bump always "remove" material
| from the surface. However, if you apply it using negative values, it
| will "add" and raise the surface.  Could it be that the gap you are
| seeing is the missing material?  Would neg values raise the level
| above your box or at least to it's bounds?
|
| Sorry Ken for emailing you for help . . . I think I finally figured out
| the problem. But of course I won't know until I see this make the post.
|
| Thanks all - just discovered these newz groups. I'm jazzed !!!   TS

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