Hi there.

[first post in a very long time]

I've just started trying out the f_ridged_mf function to create a
landscape with, but I have a slow computer (p233) and figuring out a
decent set of parameters by trial-and-error is beyond my limited
patience.  Has anyone got a "ready-made" isosurface they could post that
demonstrates good parameters and scaling to create a landscape with?
I'm thinking something along the lines of the one in Gilles's recent
masterpiece - ie a mountainous desert region.

Thanks in advance.

Andrew

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3ce4eb27@news.povray.org...
> Has anyone got a "ready-made" isosurface they could post that
> demonstrates good parameters and scaling to create a landscape with?

Here are the two I used :

// foreground
// the 0.15... at the end makes the terrain flatten in the z direction
isosurface{
    function {y-f_ridged_mf( x*0.5, y*0.5, z*0.5, 1, 2, 9, -1.3,
3,3 )*0.15*(-z+50)/80}
    max_gradient 2.4
    contained_by{box{<-2000,-0.01,-30>,<2000,1,50>}}
    translate y*-0.4
}

// mountain
// the (1-...) at the end makes the terrain flatten in the -x and -z
direction

#declare RESOLUTION = 100;
//#declare RESOLUTION = 1000;
height_field {
    function RESOLUTION,RESOLUTION {
        f_ridged_mf( z*2, y*2, x*2, 1, 2, 9, -0.5,
3,3 )*0.8*(1-y*0.98)*(x+0.2)
    }
    translate <-0.5,0,0>
    scale <120,5,60>
}

--

**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
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"Gilles Tran" <tra### [at] inapginrafr> wrote in message
news:3ce4f377@news.povray.org...

<snip>

I've not yet played with any of the h-f/function stuff in 3.5.

Can anyone give a quick explanation as to what they're for? For example, in
Gilles's post, why use a hf with the ridged mf rather than just using the ridged
mf directly?

I know, I know - I could read the docs and test things out, but I thought that a
discussion on this might be of general interest anyway.

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"Gilles Tran" <tra### [at] inapginrafr> wrote in message
news:3ce4f377@news.povray.org...

> 3ce4eb27@news.povray.org...
> > Has anyone got a "ready-made" isosurface they could post that
> > demonstrates good parameters and scaling to create a landscape with?
>
> Here are the two I used :
>
> // foreground
> // the 0.15... at the end makes the terrain flatten in the z direction
> isosurface{
>     function {y-f_ridged_mf( x*0.5, y*0.5, z*0.5, 1, 2, 9, -1.3,
> 3,3 )*0.15*(-z+50)/80}
>     max_gradient 2.4
>     contained_by{box{<-2000,-0.01,-30>,<2000,1,50>}}
>     translate y*-0.4
> }
>
> // mountain
> // the (1-...) at the end makes the terrain flatten in the -x and -z
> direction
>
> #declare RESOLUTION = 100;
> //#declare RESOLUTION = 1000;
> height_field {
>     function RESOLUTION,RESOLUTION {
>         f_ridged_mf( z*2, y*2, x*2, 1, 2, 9, -0.5,
> 3,3 )*0.8*(1-y*0.98)*(x+0.2)
>     }
>     translate <-0.5,0,0>
>     scale <120,5,60>
> }
>
> --
>
> **********************
> http://www.oyonale.com
> **********************
> - Graphic experiments
> - POV-Ray and Poser computer images
> - Posters

Thanks Gilles!  That's just the kind of thing I'm after.

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"Tom Melly" <tom### [at] tomandlucouk> wrote in message
news:3ce50a2b@news.povray.org...
> "Gilles Tran" <tra### [at] inapginrafr> wrote in message
> news:3ce4f377@news.povray.org...
>
> <snip>
>
> I've not yet played with any of the h-f/function stuff in 3.5.
>
> Can anyone give a quick explanation as to what they're for? For
example, in
> Gilles's post, why use a hf with the ridged mf rather than just using
the ridged
> mf directly?
>
> I know, I know - I could read the docs and test things out, but I
thought that a
> discussion on this might be of general interest anyway.

Not that I've tried it out yet, but I think that the height field would
render faster than an isosurface, as it is precalculated at a fixed
resolution.  That way, when it traces, the surface doesn't have to be
calculated.

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Tom Melly wrote:
> 
> [...]
> 
> Can anyone give a quick explanation as to what they're for? For example, in
> Gilles's post, why use a hf with the ridged mf rather than just using the ridged
> mf directly?

It is faster usually.  For a direct comparison see the 'landscape.pov'
demo scene from POV-Ray 3.5.  

It should be mentioned that Gilles' code does not use the classical
'hf-style' function which would have constant gradient in vertical
direction:

function {y-f_ridged_mf( x, 0, z, ...

Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
TransSkin and more: http://www.tu-bs.de/~y0013390/  
Last updated 05 May. 2002 _____./\/^>_*_<^\/\.______

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3ce50a2b@news.povray.org...
> Can anyone give a quick explanation as to what they're for? For example,
in
> Gilles's post, why use a hf with the ridged mf rather than just using the
ridged
> mf directly?

Speed was already mentioned but in this case it was also the ability to use
a low res version during the tests. And I wanted to test the feature in a
real image too.

G.



--

**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters

>

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3CE50EC8.BC3F19C1@gmx.de...
> It should be mentioned that Gilles' code does not use the classical
> 'hf-style' function which would have constant gradient in vertical
> direction:
> function {y-f_ridged_mf( x, 0, z, ...

In fact, the height_field example can also be simplified as the z coordinate
is not used.
height_field {
      function 100,100 {
        f_ridged_mf( x, y, 0, 1, 2, 9, -0.5, 3,3 )*0.5
      }
}

G.
--

**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters

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