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Thomas de Groot wrote:
> That's a thoughtful analysis, Jim. Thank you.
>
> I suppose that all this is the reason why, when I saw this last image by
> Tek, I was immediately reminded of Hokusai's Big Wave, or some marines from
> the 17th/18th century.
>
In fact, as soon as I read the title, and before I opened the image, I
remembered this one:
http://www.irtc.org/ftp/pub/stills/2000-08-31/dmwave.jpg
But yes, the portrayal of water might be a fascinating subplot to the
history of art, but I have never come across such a treatment. I wonder
what Gombrich might have said about it.
Also there are pictures like this that I grew up with and loved:
http://www.ago.net/www/picture.three/harris.jpg
http://tinyurl.com/ylzcm6
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"Tek" <tek### [at] evilsuperbrain com> wrote:
>
>
> ...but foam shouldn't be able to have sharp edges.
>
> I can't really think of a way to smooth off ridges in a ridged fractal, so
> I'll just try to cover it up with some mist/spray effects!
>
I'm just enthralled with your water. It is *so* inspiring, and presents (to
me) a *new level* of the power of POV-Ray.
I've been doing a great deal of isosurface experimentation lately, learning
lots of new things, and there might be a way to alter those crests. The idea
involves "fading" one isosurface function into another, over a certain
distance.
What I'm thinking is this:
Fading in an f_noise3d function in the +y-direction, somewhere near the top
of the crests--to actually break them up with "bits" of tiny noise blobs, to
simulate spray. I *think* (but am not sure) that your water-wave function(s)
could be used IN the noise function, to actually vary the height at which
the noise comes into play (so that the noise doesn't just show up at a set
y-height.) I've gotten this trick to work on some isosurfaces of my
own...though not of the complexity of your waves.
My ideas are a bit tricky mathematically...and difficult to explain...but I
now have a methodology of sorts that seems to work, and that "makes sense"
to me.
I'll definitely take a look at your code--which I'm absolutely overjoyed
that you've posted--and see if I can do what I've mentioned. If successful,
I'll post an image.
Meanwhile, I'll work up a simple --VERY simple!--demonstration code example
(or two) and post it here.
Ken W.
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I had a similar idea, but the trouble is to fade in a different isosurface
on the foamy sections you need to know where those foamy sections are, i.e.
you need to modulate it by the wave function, and a smooth function
modulated by a function with hard edges is going to have hard edges. As far
as I can see this paradox is inescapable.
--
Tek
http://evilsuperbrain.com
"Kenneth" <kdw### [at] earthlinknet> wrote in message
news:web.455d57fe7adb74e76135df7c0@news.povray.org...
> "Tek" <tek### [at] evilsuperbraincom> wrote:
>>
>>
>> ...but foam shouldn't be able to have sharp edges.
>>
>> I can't really think of a way to smooth off ridges in a ridged fractal,
>> so
>> I'll just try to cover it up with some mist/spray effects!
>>
>
> I'm just enthralled with your water. It is *so* inspiring, and presents
> (to
> me) a *new level* of the power of POV-Ray.
>
> I've been doing a great deal of isosurface experimentation lately,
> learning
> lots of new things, and there might be a way to alter those crests. The
> idea
> involves "fading" one isosurface function into another, over a certain
> distance.
>
> What I'm thinking is this:
> Fading in an f_noise3d function in the +y-direction, somewhere near the
> top
> of the crests--to actually break them up with "bits" of tiny noise blobs,
> to
> simulate spray. I *think* (but am not sure) that your water-wave
> function(s)
> could be used IN the noise function, to actually vary the height at which
> the noise comes into play (so that the noise doesn't just show up at a set
> y-height.) I've gotten this trick to work on some isosurfaces of my
> own...though not of the complexity of your waves.
>
> My ideas are a bit tricky mathematically...and difficult to explain...but
> I
> now have a methodology of sorts that seems to work, and that "makes sense"
> to me.
>
> I'll definitely take a look at your code--which I'm absolutely overjoyed
> that you've posted--and see if I can do what I've mentioned. If
> successful,
> I'll post an image.
>
> Meanwhile, I'll work up a simple --VERY simple!--demonstration code
> example
> (or two) and post it here.
>
> Ken W.
>
>
>
>
>
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Jim Charter <jrc### [at] msncom> wrote:
> But yes, the portrayal of water might be a fascinating subplot to the
> history of art, but I have never come across such a treatment. I wonder
> what Gombrich might have said about it.
>
I saw a video by Neil MacGregor, then the director of the National Gallery,
where he discussed this briefly. IIRC water was a difficult subject before
the use of oils. When tempera was used artists could not get the
transparency needed. Maybe water is too dificult to paint to have much of a
history.
matchstick men)
Stephen
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Wasn't it Tek who wrote:
>I had a similar idea, but the trouble is to fade in a different isosurface
>on the foamy sections you need to know where those foamy sections are, i.e.
>you need to modulate it by the wave function
It's not quite as complicated as that because your wave function
modulates the height, so you just need your blending function to be a
function of height. It doesn't need to know where the height comes from.
I quickly threw together this proof-of-concept. The actual functions I
use here are pretty naff, they just demonstrate a mechanism.
#version 3.6;
global_settings {assumed_gamma 1.0}
camera {location <0,5,-10> look_at <0,0,0> angle 40}
background {rgb 1}
light_source {<-30, 100, -30> color rgb 1}
#include "functions.inc"
#declare WAVE = function {f_bozo(x,0,z)*2 +y -0.5}
#declare FOAM = function {f_bozo(x*10,y*10,z*10)-0.5}
#declare BLEND = function {
WAVE(x,y,z) -
FOAM(x,y,z) * (atan(y*20)+pi/2) *0.35
}
isosurface {
function { BLEND(x,y,z) }
max_gradient 12
contained_by{box{-3,3}}
pigment { rgb <.1,.3,.6> }
}
(atan(y*20)+pi/2) goes smoothly from 0.05 to pi as y goes from -1 to +1,
so it adds more FOAM at the top of the WAVE. There are almost certainly
better functions to use.
--
Mike Williams
Gentleman of Leisure
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That's still going to suffer the same problem. I'll try to break it down for
you:
The wave function has a hard edge
so the height has a hard edge
so anything modulated by either height or the wave function will have that
hard edge
And, as an aside, my wave function isn't actually a height function, it has
some overlaps.
--
Tek
http://evilsuperbrain.com
"Mike Williams" <nos### [at] econymdemoncouk> wrote in message
news:Iv3RkEA$IYXFFwU$@econym.demon.co.uk...
> Wasn't it Tek who wrote:
>>I had a similar idea, but the trouble is to fade in a different isosurface
>>on the foamy sections you need to know where those foamy sections are,
>>i.e.
>>you need to modulate it by the wave function
>
> It's not quite as complicated as that because your wave function
> modulates the height, so you just need your blending function to be a
> function of height. It doesn't need to know where the height comes from.
>
> I quickly threw together this proof-of-concept. The actual functions I
> use here are pretty naff, they just demonstrate a mechanism.
>
> #version 3.6;
> global_settings {assumed_gamma 1.0}
> camera {location <0,5,-10> look_at <0,0,0> angle 40}
> background {rgb 1}
> light_source {<-30, 100, -30> color rgb 1}
> #include "functions.inc"
>
>
> #declare WAVE = function {f_bozo(x,0,z)*2 +y -0.5}
> #declare FOAM = function {f_bozo(x*10,y*10,z*10)-0.5}
>
> #declare BLEND = function {
> WAVE(x,y,z) -
> FOAM(x,y,z) * (atan(y*20)+pi/2) *0.35
> }
>
> isosurface {
> function { BLEND(x,y,z) }
> max_gradient 12
> contained_by{box{-3,3}}
> pigment { rgb <.1,.3,.6> }
> }
>
>
> (atan(y*20)+pi/2) goes smoothly from 0.05 to pi as y goes from -1 to +1,
> so it adds more FOAM at the top of the WAVE. There are almost certainly
> better functions to use.
>
> --
> Mike Williams
> Gentleman of Leisure
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"Jim Charter" <jrc### [at] msncom> schreef in bericht
news:4559e4c6$1@news.povray.org...
>
> In fact, as soon as I read the title, and before I opened the image, I
> remembered this one:
> http://www.irtc.org/ftp/pub/stills/2000-08-31/dmwave.jpg
>
I totally forgot that one!!!
>
> But yes, the portrayal of water might be a fascinating subplot to the
> history of art, but I have never come across such a treatment. I wonder
> what Gombrich might have said about it.
>
> Also there are pictures like this that I grew up with and loved:
> http://www.ago.net/www/picture.three/harris.jpg
> http://tinyurl.com/ylzcm6
Aah! Those two are beautiful! Very much my type of painting!
This: http://www.artrenewal.org/asp/database/image.asp?id=30208 is one of
the paintings I was thinking about.
Thomas
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Thomas de Groot wrote:
> Aah! Those two are beautiful! Very much my type of painting!
I always loved that the striated waves might be:
-the artifacts of his painting style of simplified solids
-waves caught in some mystic frozn moment
-waves actually frozen as ice
>
> This: http://www.artrenewal.org/asp/database/image.asp?id=30208 is one of
> the paintings I was thinking about.
>
Wow, I was dimly aware of these paintings if at all. And so very close
to Tek's image! Seems my blather was even closer to the target than I
realized :0
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"Jim Charter" <jrc### [at] msncom> schreef in bericht
news:455e2013$1@news.povray.org...
>>
>> This: http://www.artrenewal.org/asp/database/image.asp?id=30208 is one of
>> the paintings I was thinking about.
>>
> Wow, I was dimly aware of these paintings if at all. And so very close to
> Tek's image! Seems my blather was even closer to the target than I
> realized :0
Absolutely! I had this painting in the back of my mind, and when I saw it
again, I immediately thought: "Tek".
And yes, your analysis was very close to the point indeed. A great talent
you have for this (no kidding).
Thomas
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Tek wrote:
> What do you think?
I was waiting to see if you would work more on the ship and the sky
to make them look more realistic. The water is completely superb, but
the ship and the sky are a bummer.
I would have nominated this image for the HoF if the ship and the
sky were better.
(Of course it's in no way up to me to decide what goes and doesn't
go there, but I would have mentioned this to the team for them to
judge.)
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