Re: [Algorithms] It looks terrible (was: Lightmap Terrain)

[Jim O. <j.o...@in...>]

Hey Niki,

Some suggestions which might make your lightmap (and not to forget your
terrain) look better/nicer. Maybe you have already considered these, but
then again, you never know :-)

- Perhaps you could use a lighter ambient color (instead of something
nearing total blackness, say about 20-25% gray or something). Near black
shadows are not really common in real life, specially not in open terrains -
always plenty of ambient light.

- When raytracting your lightmap, you could perhaps use the corners of each
pixel/texel instead of the centers and then use the average of the four
corners as the pixel's color, essentially applying a bilinear filter to your
light map.

- It is just a hunch (no scientific basis, other than my own observations),
but it might look good if you lighten the shadow areas based on the slope of
the terrain, so that shadows on steep areas look darker than those on flat
areas, which in my eyes also happens in reality. Reason for this effect
could be that more diffuse light is being reflected on the flat areas by the
clouds, but again, I have no scientific basis for this assumption.

Jim Offerman

Innovade
- designing the designer

----- Original Message -----
From: "Klaus Hartmann" <k_h...@os...>
To: <gda...@li...>
Sent: Sunday, August 27, 2000 6:32 PM
Subject: Re: [Algorithms] It looks terrible (was: Lightmap Terrain)


> Welcome, Ralf :)
>
> ----- Original Message -----
> From: Ralf Schneider <rap...@ra...>
> > Niki,
> >
> > well it do NOT look that terrible!
> > it's a lightmap, isn't it? what du you suspect?
>
> What I suspect is a nice image :) See, I've actually tried this shadow
stuff
> in my terrain engine, and in 3D it looks far worse than the lightmap. I
> tried this with a hybrid multifractal, though... maybe it looks better
with
> real world data as show in the image. Gotta try this, but it's a bit more
> work.
>
> > shadows make scenes nore realistic, not neccesarily beautiful.
>
> This is a good description. The unrealistic dot-product-only lit scene (in
> 3D) looks much better, even though it's not as realistic as the shadowed
> version.
>
> >you are loosing visual information if yo add shadows to a top down view
of
> a heightfield. you know that already, because you are trying to avoid it,
by
> using a second light source instead of ambient light (we can say the
second
> light is simulating the reflection of the sun at the other mountain...).
>
> Yes, this is quite a problem. If I use no second light source, then
there's
> zero shading on the faces opposite to the sun, which basically means that
I
> lose all the nice features. If, on the other hand, I use a secondary light
> source (plus shadows), then I get artifacts as the one's in the
upper-right
> shadow-area of the image I posted. This looks as if I used false gays (as
in
> false color). In 3D this becomes even worse.
>
> > take a look at some landscape/mountain top-down photos. i guess, you
will
> recognice you lightmap is ok!
>
> You should see John Ratcliff's work... I remember his moon-lightmap and it
> looks great. John, are you still a member of this list? Could you please
> upload that moon-lightmap of yours again?
>
> Niki
>
>
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