Study No 1 of a series of 1 so far :-)

First image is an earlier render when everything was going well.

I thought I had just a few things to sort out: add some
smoke, use an area light to get rid of the particle shadows,
use photons for the glass and fix up the max_gradient on the
isosurfaces.

As it turned out about half of what I did from then on made
things significantly worse.  Look at the second image and
you can see what I mean.

-- 
I would've gotten away with it too, if it wasn't for those pesky kids!

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Attachments:
Download 'sample.jpg' (49 KB) Download 'still-life.jpg' (41 KB)

Preview of image 'sample.jpg'

Preview of image 'still-life.jpg'

Filter looks to light - otherwise excellent!

--
Rick

Kitty5 NewMedia http://Kitty5.co.uk
POV-Ray News & Resources http://Povray.co.uk
TEL : +44 (01270) 501101 - FAX : +44 (01270) 251105 - ICQ : 15776037

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Rick [Kitty5] wrote:

> Filter looks to light - otherwise excellent!

I'm not happy with it, hence the 2 images.
I've sorted out the chunk of ash, it looks better after
adding a surface texture and playing more with isosurfaces.

The smoke is still poor, I am using a julia_fractal atm.

Any suggestions for a better cigarette smoke anyone?

The main issue is that the smoke is not a simple column.

From observation the smoke particles flow mainly from
just behind the burning paper edge and are drawn forwards
and upwards by the heat from the burning tobacco, like
a sheet but with the edges folded in a spiral. At some
point they hit a cooler layer of air and some disperse
sideways, and accumulate, then that iterates (am I
sounding obsessive? :-).

FYI

Yes I smoke, Yes I'd like to give up, No I don't want
lots of self-help suggestions :-). I thought this might
help me give up, but I smoked soooo many cigarettes
trying to get this right...

I think I'm addicted to pov too

> --
> Rick
> 
> Kitty5 NewMedia http://Kitty5.co.uk
> POV-Ray News & Resources http://Povray.co.uk
> TEL : +44 (01270) 501101 - FAX : +44 (01270) 251105 - ICQ : 15776037
> 
> PGP Public Key
> http://pgpkeys.mit.edu:11371/pks/lookup?op=get&search=0x231E1CEA

-- 
I would've gotten away with it too, if it wasn't for those pesky kids!

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About those photons: Perhaps try a different
autostop, like .25 or such. With autostop 0 it
may happen that it will stop shooting photons
as soon as it completes a full turn without
hitting the object. This happens nicely with a
torus blocking the light, but might also be
happening with the cigarette. Don't use arealight
for the photons, in my experience that made
things worse.
 About the smoke: try to model a blob and fill it
with scattering media. Best would be to make
two thick rims which spread out and turbulate,
and some connection between these two. These
two rims seem to be the main issue for realistic
cigarette smoke, at least to me.

Aside of that, nice job. The floor needs a realistic
texture, then you'd get a nice image.

Regards,
Tim

--
Tim Nikias v2.0
Homepage: http://www.digitaltwilight.de/no_lights
Email: Tim### [at] gmxde

> Study No 1 of a series of 1 so far :-)
>
> First image is an earlier render when everything was going well.
>
> I thought I had just a few things to sort out: add some
> smoke, use an area light to get rid of the particle shadows,
> use photons for the glass and fix up the max_gradient on the
> isosurfaces.
>
> As it turned out about half of what I did from then on made
> things significantly worse.  Look at the second image and
> you can see what I mean.
>
> --
> I would've gotten away with it too, if it wasn't for those pesky kids!

Post a reply to this message

Tim Nikias v2.0 wrote:

> About those photons: Perhaps try a different
> autostop, like .25 or such. With autostop 0 it
> may happen that it will stop shooting photons
> as soon as it completes a full turn without
> hitting the object. This happens nicely with a
> torus blocking the light, but might also be
> happening with the cigarette. Don't use arealight
> for the photons, in my experience that made
> things worse.
>  About the smoke: try to model a blob and fill it
> with scattering media. Best would be to make
> two thick rims which spread out and turbulate,
> and some connection between these two. These
> two rims seem to be the main issue for realistic
> cigarette smoke, at least to me.
> 
> Aside of that, nice job. The floor needs a realistic
> texture, then you'd get a nice image.
> 
> Regards,
> Tim
> 

Thanks, I'll try that. My main issue was that when I turned
the area light on, the dispersed ash turned to powder and the
chunk of ash, which is an isosurface, looked like a cylinder
with a texture. I fixed the dispersed ash problem by randomizing
the shade of grey for each particle, the ash chunk also yielded
to brute force and ignorance, which just leaves the smoke. I'd
tried a crude blob model earlier on, but that was so bad I opted
for a fractal. I'll try again with blobs.

-- 
I would've gotten away with it too, if it wasn't for those pesky kids!

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