Fabian BRAU wrote:

> I already saw some attempt to create wood
> with hieghtfield, the result was more or less good but it took
> several weeks for the guy to get a "good" result so...

But does displacement mapping solves the problem of having a good displacement map
in the first place ?
For me the main problem in using isosurfaces for displacement mapping in Megapov
is that it is restricted to what isosurfaces can do. For instance, using it on CSG
is not straigthforward, if not impossible. The second problem is that it's not
fast. Otherwise it's not that complicated.

Below is a setup for a floor with displacement mapping in Megapov (equivalent to a
height field).
#declare hf=function{pigment{image_map{png "floorbump" interpolate 2} rotate
x*90}}
#declare rs=0.005;
isosurface{function{y - hf(x,y,z)*rs } contained_by{box{<-2,-1,-1>,<2,1,2>}}
threshold 0    rotate x*-90
        texture{pigment{image_map{png "floormap"}} finish{ambient 0 diffuse 0.8
specular 0.2 roughness 0.1} rotate x*90 }
}

And a picture here (uses official focal blur, official caustics, a big image map
for the texture and another big one for the displacement).

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Attachments:
Download 'parquet.jpg' (30 KB)

Preview of image 'parquet.jpg'

Gilles Tran wrote:
> 
> But does displacement mapping solves the problem of having a good displacement map
> in the first place ?

If i see it right your sample is similar to the heightfield solution.  The
obvious starting point would be to take the image map used for the texture and
try to get a reasonable corresponding heightfield/isosurface map using filter
functions.  

[...]
> The second problem is that it's not
> fast. Otherwise it's not that complicated.
> 

heightfields should be a lot faster than isosurfaces in many cases, but of
course they are not that flexible.

Christoph

--
Christoph Hormann <chr### [at] gmxde>
Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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Exactly!! I forgot that we can use image map in iso surface :).
But yes this slow but feasible!
I will have a look!

Fabian.


> 
> Fabian BRAU wrote:
> 
> > I already saw some attempt to create wood
> > with hieghtfield, the result was more or less good but it took
> > several weeks for the guy to get a "good" result so...
> 
> But does displacement mapping solves the problem of having a good displacement map
> in the first place ?
> For me the main problem in using isosurfaces for displacement mapping in Megapov
> is that it is restricted to what isosurfaces can do. For instance, using it on CSG
> is not straigthforward, if not impossible. The second problem is that it's not
> fast. Otherwise it's not that complicated.
> 
> Below is a setup for a floor with displacement mapping in Megapov (equivalent to a
> height field).
> #declare hf=function{pigment{image_map{png "floorbump" interpolate 2} rotate
> x*90}}
> #declare rs=0.005;
> isosurface{function{y - hf(x,y,z)*rs } contained_by{box{<-2,-1,-1>,<2,1,2>}}
> threshold 0    rotate x*-90
>         texture{pigment{image_map{png "floormap"}} finish{ambient 0 diffuse 0.8
> specular 0.2 roughness 0.1} rotate x*90 }
> }
> 
> And a picture here (uses official focal blur, official caustics, a big image map
> for the texture and another big one for the displacement).
> 
>   ------------------------------------------------------------------------
>  [Image]

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Christoph Hormann wrote:

> If i see it right your sample is similar to the heightfield solution.  The
> obvious starting point would be to take the image map used for the texture and
> try to get a reasonable corresponding heightfield/isosurface map using filter
> functions.

Which exactly what I did here. The map was desaturated, and then I made a copy of it.
On
this one I painted the planks white, leaving only the gaps black. I gaussian-blurred
it
and then added this map to the previous map.

> heightfields should be a lot faster than isosurfaces in many cases, but of
> course they are not that flexible.

Heightfields are surely faster in the case of  flat objects. I rendered the previous
picture with a height field instead of an isosurface and it rendered 5 times faster
for
an identical output (no need to post it !).
Their main problem is that they are not tileable (unless you make copies of them and
stitch them together) while an isosurface can be of any size.

G.

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Gilles Tran wrote:

> Heightfields are surely faster in the case of  flat objects. I rendered the previous
> picture with a height field instead of an isosurface and it rendered 5 times faster
for
> an identical output (no need to post it !).
> Their main problem is that they are not tileable (unless you make copies of them and
> stitch them together) while an isosurface can be of any size.

 And they consume much more memory, and have a finite resolution, while
isosurfaces can have infinite resolution (with precedural displacement).
 Happily, both exists !  Twice the fun !

Fabien.

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What's going on here?  The pots seem to come out of the picture like
one of them 3D glasses things.  Has a chillingly realistic feel to it
but something in there lookks very flat at the same time, gives me a 
slight feeling of vertigo.  

-- 
Cheers
Steve              email mailto:ste### [at] zeroppsuklinuxnet

%HAV-A-NICEDAY Error not enough coffee  0 pps. 

web http://www.zeropps.uklinux.net/

or  http://start.at/zero-pps

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In article <3993ADDC.EA0B3F81@umh.ac.be>, Fabian BRAU 
<Fab### [at] umhacbe> wrote:

> There is only image map in this scene :).

Yes, but the map is tiled over the vases, right? It isn't a single image 
wrapped over the vase. So lighting can affect it as it normally would. 
However, it looks like much of the "lighting" effect on the wood is part 
of the image_map.


> Procedurial wood look always fake :).

Not always...I have seen some very convincing wood textures, some which 
you really couldn't tell from real wood. And no offense, but even many 
of the less convincing ones looked better than this. There is a very 
noticeable discontinuity between the bases of the vases and the wood 
texture.

-- 
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://homepage.mac.com/chrishuff/
TAG Web page: http://tag.povray.org/

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> Not always...I have seen some very convincing wood textures, some which
> you really couldn't tell from real wood. And no offense, but even many
> of the less convincing ones looked better than this.

No problem, I wait your art ...

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