Orchid XP v2 <voi### [at] devnull> wrote:
> Very cute! How did you do the stones? Blobs?

Glad you like them. I think this is my most photographic image yet.

As I said, all the stones are made from one isosurface.

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"PM 2Ring" <nomail@nomail> schreef in bericht
news:web.43242b50bddb89c077d3bc6c0@news.povray.org...
> This group of stones is a single isosurface. The wet sand is a
> normal-perturbed plane. The stone textures are the standard textures
> in stones.inc.
>
> Now I just need to figure out how to perturb the stones' positions a bit
> more...
>
>
Very, very good!!

Thomas

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Not sure about the wet sand, but those stones are fantastic! The 
polished ones are 100% real, some of the others look a bit to smooth for 
their texture, but they're great nevertheless.

Now I'm just curious: Why did you use one single isosurface?


Florian

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Thanks for the code!  It's very instructive.

Dave Matthews

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I never knew that the standard stone textures could look so realistic!  I
guess they were always used in the wrong context or at the wrong scale.
Apparantly you've used them as they were intended to be used.  Very nice!

-Nathan


"PM 2Ring" <nomail@nomail> wrote in message
news:web.43242b50bddb89c077d3bc6c0@news.povray.org...
> This group of stones is a single isosurface. The wet sand is a
> normal-perturbed plane. The stone textures are the standard textures
> in stones.inc.
>
> Now I just need to figure out how to perturb the stones' positions a bit
> more...
>
>


----------------------------------------------------------------------------
----

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"Greg M. Johnson" <gregj;-)565### [at] aolcom> wrote:
> It's nice.

Thanks, Greg.

> As a piece of art, however, I think it would look cool if you put one
> "vectorish" texture in there, to let us know it's not a photo and provide
> thematic contrast.

Ok. However, this is just a demo, not the final scene, where I'll use
isosurfaces for the water & sand. Also, I'm not sure what you mean by a
'vectorish' texture. :) I guess it means something that's obviosly digital.

> > This group of stones is a single isosurface. The wet sand is a
> > normal-perturbed plane. The stone textures are the standard textures
> > in stones.inc.

> > Now I just need to figure out how to perturb the stones' positions a bit

Any hints on this, anyone? Calling Mike Williams...

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"s.day" <s.d### [at] uelacuk> wrote:
> "PM 2Ring" <nomail@nomail> wrote:
> > This group of stones is a single isosurface. The wet sand is a
> > normal-perturbed plane. The stone textures are the standard textures
> > in stones.inc.
> >
> > Now I just need to figure out how to perturb the stones' positions a bit
> > more...
>
> Excellent stones, I spent a while trying to get good isosurface stone shapes
> for one of my IRTC entries for this round. (I didn't get as intersting
> shapes as you managed would you mind posting the source for a couple so I
> can see how you did it....

Thanks, Sean. I guess you've seen my source code by now. :)

> Here's how I created one of mine
>
> #declare  S = function { sqrt(pow(x,2) + pow(y,2) + pow(z,2)) - 2 }
>
> #declare Stone1 = isosurface {
>   function {
>
S(x,y*(1.5-y/12),z)-f_wrinkles(x*0.3,y*0.5,z*0.03)*0.05-fn_scallop_ripples(x,y,z).gray*0.001-f_wrinkles(x*3,y*4,z*4)*
0.
> 005
> }
>         accuracy isoAccuracy
>         max_gradient 2.75
>         contained_by{sphere{0,2.2}}
> }

Interesting function, though I'm not familiar with your
fn_scallop_ripples().
I don't think I would use wrinkles on pebbles like these, such patterns are
more suited to large objects like really huge stones, whole landscapes,
asteroids and planets, where the self-scaling nature of such fractal noise
can be seen over several scales at once.

A couple of suggestions about your code, though. Firstly,
fn_pattern(x,y,z).red is more efficient than fn_pattern(x,y,z).gray, and
gives identical results for a pattern using the default grayscale colour
map. Secondly, the internal functions f_r() and f_sphere will be more
efficient than your S function.

Also, I'm pretty sure that x*x is generally more efficient than pow(x,2),
although if pow() is well-optimized, the difference may be negligible. The
POV source code experts will know the answer to that one.

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Florian Brucker <tor### [at] torfboldcom> wrote:
> Not sure about the wet sand, but those stones are fantastic! The
> polished ones are 100% real, some of the others look a bit to smooth for
> their texture, but they're great nevertheless.

Ok, I cheated very slightly with the smoothness, by rendering with
 +W1200 +H900 +A0.2 +AM2 +R2
then using the good old NetPBM package to scale up by 250%, then blur with a
simple 3x3 average convolution, then scale down to 1024 x 768.

> Now I'm just curious: Why did you use one single isosurface?

Because I could. :) Seriously, this started as an exercise in making large
sets of balls using a single isosurface for efficiency. The stone textures
& then the shapes just followed as a natural progression, since I'd just
been tidying up my stones reference chart.

Now the isosurface isn't generally one of POV's faster shapes, but it's very
efficient in terms of memory usage for complex objects. Using the isosurface
like this to make multiple things from one object, it can be more efficient
to trace than tracing a heap of separate objects, and it even gets
more efficient the more things there are! I just did some quick tests
earlier tonight (using +W256 +H256 -F -D), varying the W parameter, and
here are the run times:

 1/W  Time
  10: 28s
  20: 26s
  40: 23s
  80: 19s
 160: 17s

Remember, the number of stones is 1/(W*W), so 25,600 (tiny) stones took 17
seconds, compared to 100 stones in 28 seconds! I stupidly forgot to record
the momory usage. I'll leave that as 'an exercise for the reader'. :)

At the moment I'm rendering a scene with 4 overlapping rotated copies of the
isostone grid. It looks better than I expected, although the stones still
need more perturbing. I've added a bit of y-randomness in the positioning,
and I'm seriously thinking about a bit of randomness in the orientation,
but I just don't want them to start intersecting with each other.

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"Thomas de Groot" <t.d### [at] internlnet> wrote:
> "PM 2Ring" <nomail@nomail> schreef in bericht
> news:web.43242b50bddb89c077d3bc6c0@news.povray.org...
> > This group of stones is a single isosurface. The wet sand is a
> >
> Very, very good!!

Thanks, Thomas. If a geologist likes my stones, they must be good! :)

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"Dave Matthews" <dav### [at] mnwestedu> wrote:
> Thanks for the code!  It's very instructive.

Always a pleasure to give something back to the POV community, Dave. Thanks
once again everyone for all the positive feedback!

And thanks should go to Mike Williams, for his excellent isosurface
tutorials. Especially that neat trick of using mod()...

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