Not really any shoreline intended in the first place, just so happens there is
one anyway.  It's only a thin line running along the edge where islands and
water meet.  The water is a box extending below the island isosurface extent.
The upper surface (being the water) is very slightly above 0*y.  Only a normal
using a noise3d 'function' is used for the water, not actual displacement.
But that isn't the problem.  Not caused by refraction either, I removed both
finish and normal leaving only pigment.  Also, fog was commented out to check
that.  Seems to be nothing wrong except a peculiarity going on with the island
isosurface.  Which btw this scene file started out as the mtn&lake.pov demo
for MegaPov and I didn't see anything wrong with it before I changed several
parts of the equation.  'max_trace_level 10' didn't make any difference, along
with some haphazard guesses for threshold, sign, max_gradient, etc.
If anyone has encountered this kind of thing and/or has any ideas for a fix I
welcome your thoughts.

P.S.  the clouds are a isosurface too but ignore them, not exactly turning out
like I planned.  Forgot to mention that if the pigment color of the water is
increased through higher ambient, diffuse I believe it diminishes the dark
bordering line except at one point I couldn't seem to do that either.

Bob
--
omniVerse http://users.aol.com/persistenceofv/all.htm

Post a reply to this message

Attachments:
Download 'desertisles.jpg' (34 KB)

Preview of image 'desertisles.jpg'

On further checking I didn't get anywhere with this apparent "bug", which
shows when the water box is set amid the isosurface.  Only thing needed to see
the defect (can't be certain it is though) is to have a pigment with filter or
transmit for the water.  It's not caused by any other texturing such as
normals and finishes in either the water or island parts.
This pair of attached renders makes it very clear to see.  The top is without
the water to show the unbroken isosurface.  Bottom image has a filtered
pigment "water" and a normal and finish, but it still does this without like
I've said.

"Bob Hughes" <per### [at] aolcom?subject=PoV-News:> wrote in message
news:393dc887@news.povray.org...
| a thin line running along the edge where islands and
| water meet.  The water is a box extending below the island isosurface
extent.
| The upper surface (being the water) is very slightly above 0*y

Whether the surface is at 0*y or above or below makes no difference.

Bob

Post a reply to this message

Attachments:
Download 'isobug1.jpg' (28 KB)

Preview of image 'isobug1.jpg'

I really know nothing about isosurfaces, but for me it looks like the
isosurface is "hovering" over the water and casting a shadow on it. Can you
align the camera with the watersurface and look "under" the isosurface?
It reminds me of some heightfields, were I set the water_level above the
plane for the water ...

You use noise3d for the water (which I also know really nothing about),
perhaps it extends the "clipping-box" (if there is something like that) of
the water-box in y-direction? [What should that have to do with filter or
transmit? Don't know]

Just the thoughts of a newbie, perhaps it helps (probably not :-))

Marc-Hendrik

Bob Hughes schrieb in Nachricht <393e9bbd@news.povray.org>...
>On further checking I didn't get anywhere with this apparent "bug", which
>shows when the water box is set amid the isosurface.  Only thing needed to
see
>the defect (can't be certain it is though) is to have a pigment with filter
or
>transmit for the water.  It's not caused by any other texturing such as
>normals and finishes in either the water or island parts.
>This pair of attached renders makes it very clear to see.  The top is
without
>the water to show the unbroken isosurface.  Bottom image has a filtered
>pigment "water" and a normal and finish, but it still does this without
like
>I've said.

Post a reply to this message

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

Post a reply to this message

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

Post a reply to this message

Attachments:
Download 'isobug2.jpg' (3 KB)

Preview of image 'isobug2.jpg'