Hello all,

I'm really hoping someone here can tell me what I'm doing wrong here. I'm
more of a novice than a newbie to PovRay, but this is a major brick wall.

In short, I'm trying to recreate the media effects displayed in the sample
image for the menu item under Insert | Special Effects | Atmospheric Media.
Unfortunately, even though I finally found the source file for that image
and copied the code into my scene (only changing position numbers), the best
I get is something that resembles an oil truck on fire.

I've scrambled my grey fluff over this almost all day and I'm finally
cooked. Google returns absolutely nothing useful (the Bryce tutorial on how
to do it was interesting but entirely irrelevant). I must appeal to those of
you that know what you're doing better than I (or at least drink coffee).

I'm still alive enough to realize that you probably can't help me without
reading my code, so please feel free to download my 939KB file here:
http://www.roboticsresources.com/spottedcowstudios/media.pov . I know it's
huge...long story. Skip from line 103 to line 24150 if you don't want to die
of boredom. You may get a bunch of errors on the LDRAW stuff; just comment
it out or cut it completely. Oh, and you'll need the Lens.inc file I'm
using: http://www.roboticsresources.com/spottedcowstudios/lens.inc.

And as for what I'm trying to do (no, the pillar of smoke is not what I
want!): there is a light source behind the white figure standing in the
middle of the cloud (comment out the media and you'll see him there). What I
want to do is create an animation where the light source moves vertically
behind him, illuminating media around the figure so that it looks like you
can see the light rays (sometimes you see this with the sun and clouds, or
in a dusty room with strong sunlight). I can do the animation itself easily
enough, but somehow a square black smoke cloud isn't exactly the kind of
atmospheric media I had in mind. It's a common enough theatrical trick, but
I'm having trouble simulating it for reasons unknown and incomprehensible to
me.

If someone could *please* tell me what I'm doing wrong I will be grateful
for a long, long time (I won't be around here for eternity, sorry).

Thanks,
-Mike Thorn
"I don't need help. I need a personal PovRay consultant."

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"Mike Thorn" <fil### [at] roboticsresourcescom> wrote in message
news:404fe8e3$1@news.povray.org...
> Hello all,

Hi...

> In short, I'm trying to recreate the media effects displayed in the sample
> image for the menu item under Insert | Special Effects | Atmospheric
Media.

Ugh... that's one of my little contributions. That room with a window isn't
as simple as it looks. Simple to get the media looking good, I mean. Media
seldom is easy when it comes to using it under varying circumstances, as you
must know by now.

> reading my code, so please feel free to download my 939KB file here:
> http://www.roboticsresources.com/spottedcowstudios/media.pov . I know it's
> huge...long story. Skip from line 103 to line 24150 if you don't want to
die
> of boredom. You may get a bunch of errors on the LDRAW stuff; just comment
> it out or cut it completely. Oh, and you'll need the Lens.inc file I'm
> using: http://www.roboticsresources.com/spottedcowstudios/lens.inc.
>
> And as for what I'm trying to do (no, the pillar of smoke is not what I
> want!): there is a light source behind the white figure standing in the
> middle of the cloud (comment out the media and you'll see him there). What
I
> want to do is create an animation where the light source moves vertically
> behind him, illuminating media around the figure so that it looks like you
> can see the light rays (sometimes you see this with the sun and clouds, or
> in a dusty room with strong sunlight).

Ok. Wow, that is quite a file so I was glad to find out that the fix might
be as uncomplicated as reducing the scattering value by a factor of ten to
0.01 instead of the current 0.1. Apparently it's only a matter of a largish
box in which the media scatters too much, thus making for a thick density.
You might need to tweak it further, for instance the 'extinction' might be
able to go higher or add slight 'absorption'.

Unfortunately, asking for help with media can entail all sorts of "in the
eye of the beholder" stuff, so you might get varying opinions (even from
yourself) until it looks the way you want it.

My question to you would be: is that stretched background image what you
intended? I'm guessing it's Earth clouds.

-- 
Bob H.
http://www.3digitaleyes.com

Post a reply to this message

"Hughes, B." <omn### [at] charternet> wrote in message
news:404ff5c3$1@news.povray.org...
> Ugh... that's one of my little contributions. That room with a window
isn't
> as simple as it looks. Simple to get the media looking good, I mean. Media
> seldom is easy when it comes to using it under varying circumstances, as
you
> must know by now.

Well, it'll be a long time before I decide to use media again, if that says
anything. :-)

> Ok. Wow, that is quite a file so I was glad to find out that the fix might
> be as uncomplicated as reducing the scattering value by a factor of ten to
> 0.01 instead of the current 0.1. Apparently it's only a matter of a
largish
> box in which the media scatters too much, thus making for a thick density.
> You might need to tweak it further, for instance the 'extinction' might be
> able to go higher or add slight 'absorption'.

All Greek to me but I'll give it a whirl. Thanks so much for the
suggestions. I'm very, very happy to hear it might be an easy fix! :-)

> Unfortunately, asking for help with media can entail all sorts of "in the
> eye of the beholder" stuff, so you might get varying opinions (even from
> yourself) until it looks the way you want it.

The eye of this beholder is just abou frazzled, so I don't think it can
afford to be too picky. Unfortunately I know that the eyes of the beholders
that will be looking at this animation are going to be very critical indeed,
so I'm striving for perfection (and sometimes failing).

> My question to you would be: is that stretched background image what you
> intended? I'm guessing it's Earth clouds.

Yes, that's what it is. At that close of a camera angle it does appear
pixelated (I think my original image was 800x600). Too late to change now,
though - and I haven't gotten around to reading the part of the
documentation on sky spheres yet, so I don't know too much about layers and
all that. Eventually I'll get to it.

Thanks so much, Bob. You don't know how much frustration you've saved me. My
family thanks you, too. ;-)

-Mike
"I don't need help. I need a personal PovRay consultant."

Post a reply to this message

"Mike Thorn" <fil### [at] roboticsresourcescom> wrote in message
news:40505b50$1@news.povray.org...
>
> "Hughes, B." <omn### [at] charternet> wrote in message
> news:404ff5c3$1@news.povray.org...
>
> Well, it'll be a long time before I decide to use media again, if that
says
> anything. :-)

Never say never when doing something in POV and you might get somewhere...
eventually.
;-)

> > My question to you would be: is that stretched background image what you
> > intended? I'm guessing it's Earth clouds.
>
> Yes, that's what it is. At that close of a camera angle it does appear
> pixelated (I think my original image was 800x600). Too late to change now,
> though - and I haven't gotten around to reading the part of the
> documentation on sky spheres yet, so I don't know too much about layers
and
> all that. Eventually I'll get to it.

Oh, of course, how stupid of me. I should have looked but I sped right
through your scene file to only check on the media and replied too fast to
notice. You used the default mapping, so it's projected into +z direction on
a xy plane. That's why it stretched at the left side, as viewed from the
camera. You might want to get that changed to use map_type 1 for spherical
mapping. And please consider that sky_sphere isn't like a regular object in
the following:

sky_sphere {
// nothing here, unless maybe you used a shaped object instead
  pigment { image_map {"clouds" map_type 1}
  rotate <0,-70,0> // transormations go here... or below
  }
//  rotate <0,-70,0> // would turn both the image and object
}

Good luck with your animation. Always glad to help any way I can.

-- 
Bob H.
http://www.3digitaleyes.com

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