Ahhhhh, you got us all excited for nothing!

Here I thought someone found the grail...

-Mike

Post a reply to this message

Btw, just getting your goat, assuming you have one.  ;)

-Mike

Post a reply to this message

Simon de Vet wrote in message <39A74B70.9EF7F5E0@istar.ca>...
>
>
>Peter Warren wrote:
>
>> ps. how long?
>
>How long to figure it out? About 2 days.How long to render? About 2
>minutes, with radiosity (1 min without)
>How long till I explain the method? Tomorrow, I hope. I want to read more
>ego-boosting comments first :)


2 minutes?
Consider you ego boosted.

Peter Warren
Proud Povray user since 1996

Post a reply to this message

Image_map and IRTC? Bite your tongue!

Grim

Post a reply to this message

Simon de Vet wrote:
> 
> Ding ding! We have a winner!
> 
> I guess this shows that, on occasion, imagemaps aren't the terrible solution
> they're made out to be.
> 

Thanks for the day of hopeful doubt :-)

This one really isn't that bad, even though i'm not so sure, whether light
position of scene and image_map fit together.  NTL, it's well done, the fact
that nobody was able to tell exactly that it is image_map speaks for it

> I am planning, however, to create some POV code to generate semi-realistic
> clouds procedurally. In my experimentation, I have made some progress, and I
> think it should be do-able.
> 

But not with that rendering time :-)

Christoph

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

Post a reply to this message

Wow!

Post a reply to this message

I think the person who said "AWESOME ROLEX" was the most accurate this
time. Nicely done, tho. You fooled (almost) everybody!

Simon de Vet wrote:
> 
> Equiprawn wrote:
> 
> > Hey,
> >
> > <ego_boosting_comment> Cool image! </ego_boosting_comment>
> >
> > Now some observations :) Firstly, thought it is hard to tell with the water,
> > there doesn't seem to be any shadows cast, either on the water surface or on
> > other clouds. Also, judging from the ship the lighting is quite low, and
> > almost directly to the left of the ship - yet teh lighting on the clouds
> > seems to be quite high and from a source somewhere behind the camera. So I
> > am guessing that the clouds aren't a real-time lit object. I don't want to
> > hur any feeling here, but ... imagemap?
> 
> Ding ding! We have a winner!
> 
> I guess this shows that, on occasion, imagemaps aren't the terrible solution
> they're made out to be.
> 
> I am planning, however, to create some POV code to generate semi-realistic
> clouds procedurally. In my experimentation, I have made some progress, and I
> think it should be do-able.
> 
> In the mean time, with time running out before the IRTC entry is due, I found a
> very reasolable stop-gap solution, as all the positive comments attest to.
> 
> Simon

Post a reply to this message

Christoph Hormann wrote:

> Simon de Vet wrote:
>
> > I am planning, however, to create some POV code to generate semi-realistic
> > clouds procedurally. In my experimentation, I have made some progress, and I
> > think it should be do-able.
> >
>
> But not with that rendering time :-)

I'm not so sure about this.

I've looked at other people's cloud techniques, and they all use 3-d to generate
3-d looking clouds. Some use media, or isosurfaces, or stacked planes, but all use
actuall objects.

When I look at the clouds around me, most are way too far away to look 3-d. 3-d
objects are usually shaded based on the angle of the incomming light (diffuse
shading) and on self shadowing. Clouds, on the other hand, have a bit of this, but
the vast majority of the shading comes from the extinction of light as it passes
through the water vapour.

I've been looking at clouds not as 3-d objects, but as 2-d objects, painted onto a
giant sphere. If treated this way, I think that most of the effects can be
generated with complex textures on a skysphere, which are very quick to render.

http://freespace.virgin.net/hugo.elias/models/m_main.htm has a good (award
winning) example of a pigment based cloud render.

In addition, pigments can generate clouds other than puffy cumulus, like cirrus,
stratus, and realistic haze.


I'm attaching a test image I made before I gave up on this technique, due to time
limitations. It's a very early image, with no pseudo-3-d effects, but it shows how
pigments can be used to create the shape of distant thunderclouds. It's all one
pigment, generated with the 'pigment control trick' and MegaPov's spline.


Simon

Post a reply to this message

Attachments:
Download 'cloudtest1.jpg' (43 KB)

Preview of image 'cloudtest1.jpg'

A total cheat, mister!

Sure it looks good, but imagemaps are not very flexible, cause they are
not very real... Okay I use them too, but I have found that the greatest
realism is achieved when objects are modelled like in real life.

Well, your clouds are in the horisont, so unless you plan an animation
of them, or a sundown, it doesn't matter if they're real or not. And as
long as you put enough real things into the picture, people will look at
mostly them, and not the clouds... In which case you can receieve praise
with a clean conscience.


- Hugo


Simon wrote:

>> I guess this shows that, on occasion, imagemaps aren't the terrible
>> solution they're made out to be.

Post a reply to this message

Simon de Vet wrote:
> 
> Christoph Hormann wrote:
> 
> >
> > But not with that rendering time :-)
> 
> I'm not so sure about this.
> 
> I've looked at other people's cloud techniques, and they all use 3-d to generate
> 3-d looking clouds. Some use media, or isosurfaces, or stacked planes, but all use
> actuall objects.
> 
> When I look at the clouds around me, most are way too far away to look 3-d. 3-d
> objects are usually shaded based on the angle of the incomming light (diffuse
> shading) and on self shadowing. Clouds, on the other hand, have a bit of this, but
> the vast majority of the shading comes from the extinction of light as it passes
> through the water vapour.
> 

Your description of the clouds lighting seems perfectly right, but i don't agree
about the distance.  Clouds like the ones in your scene are about 3-6 km high. 
In a large scale movement animation or a fast motion film you could perfectly
see the 3d structure of those clouds.  

> I've been looking at clouds not as 3-d objects, but as 2-d objects, painted onto a
> giant sphere. If treated this way, I think that most of the effects can be
> generated with complex textures on a skysphere, which are very quick to render.
> 
> http://freespace.virgin.net/hugo.elias/models/m_main.htm has a good (award
> winning) example of a pigment based cloud render.
> 

I have seen that one before and i like it too, but NTL, the lighting used there
is not very convincing for roundish clouds, because it only makes clouds lighter
according to their general distance to the sun, while each cloud should be
somewhat lighter on it's sun side and dark on the opposite side.  

> In addition, pigments can generate clouds other than puffy cumulus, like cirrus,
> stratus, and realistic haze.

I agree, especially for high cirrus clouds the plain texture approach seems most
efficient.  

> 
> I'm attaching a test image I made before I gave up on this technique, due to time
> limitations. It's a very early image, with no pseudo-3-d effects, but it shows how
> pigments can be used to create the shape of distant thunderclouds. It's all one
> pigment, generated with the 'pigment control trick' and MegaPov's spline.
> 

That already looks quite promising for some kind of near horizon cumulus
clouds.  It only will be quite difficult to achieve realism on both near the sun
and on the opposite side.  

Christoph

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

Post a reply to this message