Yes, media... if you haven't already guessed.
Same old story, try as I might it's always a battle to get such a thing
"right" and this is as far as I've gotten with this one.
The inset is the nucleus region.  Of course it's actually there in the wide
view too  :-) just a bit tiny, the ice chunk being about 50 km wide at most.
The comet is about 4 times more distant than the Moon and the camera angle
(or telephoto zoom?) is at set to 5 in order to get a sufficient scaling to
everything.
I think anyone will notice how the star background is enhanced at the coma,
part of my troubles getting absorption, emission, scattering, density all
together.  Take off your eye glasses if you were them and get way back and
it will look fine, possibly   B-}

P.S.  don't tell me I could get a ready-made comet out of the Galaxy
Include.  I wanted to try on my own anyhow.

Bob
--
omniVerse http://users.aol.com/persistenceofv/all.htm

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Attachments:
Download 'nearearthcomet.jpg' (33 KB)

Preview of image 'nearearthcomet.jpg'

I haven't seen swirls like that in a comet's tail.

By the way, the Moon's surface is much dimmer than that in comparison to
the Earth; 
here are two shots that contain both:
http://antwrp.gsfc.nasa.gov/apod/ap950629.html
http://antwrp.gsfc.nasa.gov/apod/ap980904.html
(from the archive of Astronomy Picture of the Day)

-- 
Anton Sherwood  --  br0### [at] p0b0xcom  --  http://ogre.nu/

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"Bob Hughes" <per### [at] aolcom?subject=PoV-News:> wrote in message
news:3996e1bf@news.povray.org...
> P.S.  don't tell me I could get a ready-made comet out of the Galaxy
> Include.  I wanted to try on my own anyhow.

The comets in the Galaxy Include File don't use media, so you're still
breaking new ground! This looks very good, Bob.

-Dave

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It looks pretty good IMO, i'm just wondering about the turbulence in the tail, i
think gases normally go just strait away from the nucleus.  Maybe the nucleus
could also be a bit brighter in contrast to the tail.  

I much like the clouds of your earth, are they image mapped or made with Povray
?

Christoph

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

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I may be wrong, but I don't believe stars should be visible. Either that or
Earth should be completely washed out. If you can find a photograph that
shows otherwise I'd like to see it. Oh and shouldn't the comet have two
tails (unless its headed straight for the sun)?

Btw, nice render.

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Anton Sherwood wrote:
> 
> I haven't seen swirls like that in a comet's tail.
> 
> By the way, the Moon's surface is much dimmer than that in comparison to
> the Earth;
> here are two shots that contain both:
> http://antwrp.gsfc.nasa.gov/apod/ap950629.html
> http://antwrp.gsfc.nasa.gov/apod/ap980904.html

Hmm....  I think you should work on those textures.  The clouds dont
seem to be very convincing.

And add some AA for more realism.


> (from the archive of Astronomy Picture of the Day)

Oops!

> 
> --
> Anton Sherwood  --  br0### [at] p0b0xcom  --  http://ogre.nu/

-- 
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     flabreq      | button on a cat who wants breakfast.
        @         |      - Unattributed quote from rec.humor.funny
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"Anton Sherwood" <bro### [at] poboxcom> wrote in message
news:3996EC00.3F38CB4D@pobox.com...
| I haven't seen swirls like that in a comet's tail.

The tail was at first fairly featureless, but I wanted to get a chaotic one
for this.
I was going to put a link to a good example of comets here but didn't find
any really fine photos, Hale-Bopp abounds on the internet apparently, and
most are homegrown pictures, so I gave up.  I believe Comet Halley might be
a good example of a turbulent tail although what I have seen is more
streamer-like.  I should probably do a little more research anyway.  The
coma area might be totally wrong for that matter and should perhaps not be
extending beyond the width of the tail itself at that point.
The real difficulty is getting a unaided eye appearance, all guess-work.

| By the way, the Moon's surface is much dimmer than that in comparison to
| the Earth;

I know, accept to brighten the Earth up so much in relation to the Moon
looked wrong, or would look wrong to the casual viewer anyhow.  I had a
dimmer Moon too and that's the same circumstance.  So I compromised and went
with unreality (easiest!).

Bob

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"Dave Blandston" <gra### [at] earthlinknet> wrote in message
news:3996fb15@news.povray.org...
| "Bob Hughes" <per### [at] aolcom?subject=PoV-News:> wrote in message
| news:3996e1bf@news.povray.org...
| > P.S.  don't tell me I could get a ready-made comet out of the Galaxy
| > Include.  I wanted to try on my own anyhow.
|
| The comets in the Galaxy Include File don't use media, so you're still
| breaking new ground! This looks very good, Bob.

Oh.  Okay then.  Thanks for the moral support btw.

Bob

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"Christoph Hormann" <Chr### [at] schunteretctu-bsde> wrote in
message news:399701EC.DCC26B3C@schunter.etc.tu-bs.de...
|
| It looks pretty good IMO, i'm just wondering about the turbulence in the
tail, i
| think gases normally go just strait away from the nucleus.  Maybe the
nucleus
| could also be a bit brighter in contrast to the tail.

I believe you are right about that.  I was going on the idea of bursts of
activity, almost like on/off gases.  Just not so sure yet if that is
correct.  Will have to do more looking around at actual photos.

| I much like the clouds of your earth, are they image mapped or made with
Povray ?

Cloud image mapped onto a slightly larger sphere than the Earth surface one.
Not a greatly detailed one but it's better than trying to make that at the
same time as dealing with the comet creation.
For planetary maps have a look at this site:
http://www.lancs.ac.uk/postgrad/thomasc1/render/render.htm

Bob

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"Jetlag" <bga### [at] microsoftcom> wrote in message
news:39975d63$1@news.povray.org...
| I may be wrong, but I don't believe stars should be visible. Either that
or
| Earth should be completely washed out. If you can find a photograph that
| shows otherwise I'd like to see it. Oh and shouldn't the comet have two
| tails (unless its headed straight for the sun)?

Hi there, glad you liked it despite the shortcomings  :-)
Yes, I know, two tails.  One for dust, other for plasma, I think is how it
goes.  But I was having a tough enough time merging together the inner and
outer coma and tail as it was.  Some comets like Hale-Bopp had a great
separation of the two.  Halley's seems to not have had any from what I saw
while looking at a few photos.
Not really going for a photographic look to begin with actually.  That would
make for a oversaturated coma and very bright tail.  Along with the washed
out Earth, as you said.  Think unreal realism  :-)  Well, whatever...
Maybe I can get it looking better later, maybe not.  This is not the sort of
thing I find easy to try since it's not totally fantasy and not completely
humanly observable.

Bob

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That looks realy good Bob.  Time to animate. 

-- 
Cheers
Steve              email mailto:ste### [at] zeroppsuklinuxnet

%HAV-A-NICEDAY Error not enough coffee  0 pps. 

web http://www.zeropps.uklinux.net/

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"Steve" <ste### [at] zeroppsuklinuxnet> wrote in message
news:slr### [at] zero-ppslocaldomain...
| That looks realy good Bob.  Time to animate.

Thanks, but no thanks.  Not at 1 hour plus per frame.  Isn't going to
happen.

Bob

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Here's a changed version.  Added the ion tail and smoothed out the dust
tail, even made the coma smaller.  It can't be perfect I don't think, only
better and better (or worse, depending).
Want to credit Constantine Thomas, Kari Kivisalo, and James Hastings-Trew.
I just now got the Earthpng.zip file at Constantine's site which I
previously posted a reply to Christoph Hormann about.  I believe I had been
using the maps from David Seal's site before: http://maps.jpl.nasa.gov/

Bob

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Attachments:
Download 'nearearthcomet2.jpg' (13 KB)

Preview of image 'nearearthcomet2.jpg'

Bob Hughes wrote:
> 
> Here's a changed version.  Added the ion tail and smoothed out the dust
> tail, even made the coma smaller.  It can't be perfect I don't think, only
> better and better (or worse, depending).

better i think, just the tail should somehow thin out in the distance.  

> Want to credit Constantine Thomas, Kari Kivisalo, and James Hastings-Trew.
> I just now got the Earthpng.zip file at Constantine's site which I
> previously posted a reply to Christoph Hormann about.  I believe I had been
> using the maps from David Seal's site before: http://maps.jpl.nasa.gov/
> 

Thanks for the info, i got some similar maps lying around somewhere here but i
never used them in fact and i don't know where i got them from :-) 

Christoph 

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

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Bob Hughes wrote in message <3997f68b@news.povray.org>...
>Here's a changed version.  Added the ion tail and smoothed out the dust
>tail, even made the coma smaller.  It can't be perfect I don't think, only
>better and better (or worse, depending).
>Want to credit Constantine Thomas, Kari Kivisalo, and James Hastings-Trew.
>I just now got the Earthpng.zip file at Constantine's site which I
>previously posted a reply to Christoph Hormann about.  I believe I had been
>using the maps from David Seal's site before: http://maps.jpl.nasa.gov/
>


Now that's nice. Tail looks a bit long relative to the size of the
earth.  Maybe move the commet further from the earth.

Gail
********************************************************************
* gsh### [at] monotixcoza              * Reality.dat not found         *
* http://www.rucus.ru.ac.za/~gail/ * Attempting to reboot universe *
********************************************************************
* The best way to accelerate Windows NT is at 9.8 m/s^2      *
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"Gail Shaw" <gsh### [at] monotixcoza> wrote in message
news:39980caa@news.povray.org...
|
| Now that's nice. Tail looks a bit long relative to the size of the
| earth.  Maybe move the comet further from the earth.

Thanks, but it's titled Near Earth Comet   :-)  As I understand it comets
can be quite large objects overall.
I think you and Christoph are right though, it needs some fading out as it
goes toward the far end.  It does at the very end, many times the length you
can see here, but not in a good way.  At the same time I need to get a
curvature for the dust tail too.  Somehow, someway.

Bob

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Looks better, but shouldn't the tail fade out in back?

--
David Fontaine     <dav### [at] faricynet>     ICQ 55354965
Please visit my website: http://www.faricy.net/~davidf/

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Now it looks much better.


Bob Hughes wrote:

> ... As I understand it comets can be quite large objects overall.

  Yes, indeed they can be hundred of times the earth radius.

> ...  At the same time I need to get a curvature for the dust tail too.  

  At the scale of your images I don't think that a curvature would be
noticeable. It also depends on the viewing angle and the vector velocity
of the comet.

Alberto.

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On Mon, 14 Aug 2000 11:14:50 -0500, Bob Hughes wrote:
>"Gail Shaw" <gsh### [at] monotixcoza> wrote in message
>news:39980caa@news.povray.org...
>|
>| Now that's nice. Tail looks a bit long relative to the size of the
>| earth.  Maybe move the comet further from the earth.
>
>Thanks, but it's titled Near Earth Comet   :-)  As I understand it comets
>can be quite large objects overall.
>I think you and Christoph are right though, it needs some fading out as it
>goes toward the far end.  It does at the very end, many times the length you
>can see here, but not in a good way.  At the same time I need to get a
>curvature for the dust tail too.  Somehow, someway.

If you put it far enough in the distance, and bring your other objects
closer, you could probably use the camera angle to bend the comet.  This
may involve scaling the object much bigger than it already is, but you
already know that don't you.

You could use a stand in solid object for the test renders untill you
get it the way you want. 

-- 
Cheers
Steve              email mailto:ste### [at] zeroppsuklinuxnet

%HAV-A-NICEDAY Error not enough coffee  0 pps. 

web http://www.zeropps.uklinux.net/

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"Steve" <ste### [at] zeroppsuklinuxnet> wrote in message
news:slr### [at] zero-ppslocaldomain...
|
| If you put it far enough in the distance, and bring your other objects
| closer, you could probably use the camera angle to bend the comet.

Interesting workaround.  Problem is, I would know it's not actually curved
and that might bug me too much  :-)

Bob

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Bob Hughes wrote:

> Interesting workaround.  Problem is, I would know it's not actually curved
> and that might bug me too much  :-)

I did the attached image a couple of years ago. It is nothing but a facade
with nothing behind the walls shown. I soon after accidentally deleted the
code for the scene. To this day it really bugs me that I can't go back and
finish the building so that it can be seen from any angle.

-- 
Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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"Ken" <tyl### [at] pacbellnet> wrote in message
news:3998DC06.3A4B901A@pacbell.net...
|
| Bob Hughes wrote:
|
| > Interesting workaround.  Problem is, I would know it's not actually
curved
| > and that might bug me too much  :-)
|
| I did the attached image a couple of years ago. It is nothing but a facade
| with nothing behind the walls shown. I soon after accidentally deleted the
| code for the scene. To this day it really bugs me that I can't go back and
| finish the building so that it can be seen from any angle.

Yeah, that's not good to not have the pov script to go along with a image.
Unfinished is one thing... can't finish, a whole other matter.
Looks like you could start this over easily enough, just by following it
like a 3D blueprint.
I like castle type stuff.

Bob

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"David Fontaine" <dav### [at] faricynet> wrote in message
news:39982C4B.44338637@faricy.net...
| Looks better, but shouldn't the tail fade out in back?

More like this one.  I know it's a tiny image, just still ferreting this
thing out.

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Attachments:
Download 'nearearthcomet3.jpg' (6 KB)

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Ken wrote:

> I did the attached image a couple of years ago. It is nothing but a facade
> with nothing behind the walls shown. I soon after accidentally deleted the
> code for the scene. To this day it really bugs me that I can't go back and
> finish the building so that it can be seen from any angle.

You'll never stop kicking yourself...

--
David Fontaine     <dav### [at] faricynet>     ICQ 55354965
Please visit my website: http://www.faricy.net/~davidf/

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On Tue, 15 Aug 2000 01:14:44 -0500 "Bob Hughes"
<per### [at] aolcom?subject=PoV-News:> wrote:

>More like this one.  I know it's a tiny image, just still ferreting this
>thing out.

  Ooh, that's nice, Bob. I like the angle of the comet's path in
relation to the sun, too.

-- 
Alan - ako### [at] povrayorg - a k o n g <at> p o v r a y <dot> o r g
http://www.povray.org - Home of the Persistence of Vision Ray Tracer

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Anton Sherwood wrote:
> I haven't seen swirls like that in a comet's tail.

Oops:  http://antwrp.gsfc.nasa.gov/apod/ap960319.html

-- 
Anton Sherwood  --  br0### [at] p0b0xcom  --  http://ogre.nu/

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"Anton Sherwood" <bro### [at] poboxcom> wrote in message
news:39A33B74.7E76CB93@pobox.com...
| Anton Sherwood wrote:
| > I haven't seen swirls like that in a comet's tail.
|
| Oops:  http://antwrp.gsfc.nasa.gov/apod/ap960319.html

Yeah, I had seen that one after your first reply when looking for comet
pictures to see how I was doing with my ray traced one.  Surprisingly, most
pictures I found were black and white and not too great.
Hey, you want to see a fantastic photograph of a comet though?

http://comets.amsmeteors.org/comets/lcomets/1995o1.html

Spectacular image of Hale-Bopp.  I just now found it.  I was thinking before
that only the dust tail could appear to swirl about from changes in the
ejection of material from the nucleus as it rotated to show a different side
to the sun.  Thought the ion tails of comets were generally straight and
featureless.  Boy was I wrong.
I'll probably try to mimic this Hale-Bopp photo most of all, it's so
visually appealing.  Just need to get a idea of what's in that saturated
white area the time exposure cleared out.  I saw Hale-Bopp through a small
4" scope so I guess it wasn't clumpy but did have some directional features
in the coma area.  I looked at some of those Halley space probe pictures
recently too; very fuzzy stuff.  Maybe I'll just see what happens.

Bob

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Bob Hughes wrote:
> Hey, you want to see a fantastic photograph of a comet though?
> http://comets.amsmeteors.org/comets/lcomets/1995o1.html

Splendid pictures of a splendid comet.

I remember my last sight of it: casually looking up one evening in San
Francisco, well after maximum.  Perhaps it was self-delusion but I still
saw a hint of the double tail.

Hm, and I don't remember the total eclipse of ~1979 (for which I
travelled from Illinois to Winnipeg) at all.

-- 
Anton Sherwood  --  br0### [at] p0b0xcom  --  http://ogre.nu/

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