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Right, thanks to DKB's precision-tweaking, here's a more accurate Ringworld.
The camera is now a mere mile (about 5000ft) above the ring floor, and the
clouds are ten miles up (still a little high, I know, but close enough).
The view is from roughly halfway to the rim from the ring midplane, as
evidenced by the appearance of the arch (Thomas, I agree, this angle is
much more dramatic!).
Also in the foreground (relatively speaking - it's still over 15,000 miles
away!) is Fist-Of-God mountain, approx 1000 miles high.
I'm pretty happy with this, although I might tweak the clouds a little: the
shiny scrith peak of the mountain is slightly obscured, and the immediate
foreground is in shadow. Any comments or criticism welcomed!
Render time: ~3 hours, mostly the mountain isosurfaces.
Bill
Post a reply to this message
Attachments:
Download 'ringworld_3.jpg' (141 KB)
Preview of image 'ringworld_3.jpg'
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"Bill Pragnell" <bil### [at] hotmail com> schreef in bericht
news:web.43674e6ac49d937b731f01d10@news.povray.org...
> Right, thanks to DKB's precision-tweaking, here's a more accurate
Ringworld.
> The camera is now a mere mile (about 5000ft) above the ring floor, and the
> clouds are ten miles up (still a little high, I know, but close enough).
> The view is from roughly halfway to the rim from the ring midplane, as
> evidenced by the appearance of the arch (Thomas, I agree, this angle is
> much more dramatic!).
>
> Also in the foreground (relatively speaking - it's still over 15,000 miles
> away!) is Fist-Of-God mountain, approx 1000 miles high.
>
> I'm pretty happy with this, although I might tweak the clouds a little:
the
> shiny scrith peak of the mountain is slightly obscured, and the immediate
> foreground is in shadow. Any comments or criticism welcomed!
>
> Render time: ~3 hours, mostly the mountain isosurfaces.
>
> Bill
>
Excellent! I certainly like this view of Fist-of-God, and the setting is
very credible, as is also the atmospheric effect you have been able to
generate.
I have been experimenting these last days with media, confined to a ring
simulating the atmosphere. The results are not really satisfying, and
becomes very difficult (and slow) when a cloud layer is added. I came to the
conclusion that, in any case, the atmospheric effect would resemble a half
sphere around the camera (like you did). Further away, it would not count.
So, I am back to start in that respect, but I learned a lesson.
Thomas
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"Thomas de Groot" <t.d### [at] internlnet> wrote:
> conclusion that, in any case, the atmospheric effect would resemble a half
> sphere around the camera (like you did). Further away, it would not count.
> So, I am back to start in that respect, but I learned a lesson.
Yes, it feels like cheating, but technically a sky_sphere is cheating too.
I've played with media (and haloes, back in the day) to obtain a "complete"
atmosphere simulation in the past, and it simply isn't worth it. The
results are, as you say, indistinguishable from a filtered sky_sphere at
best.
It's no substitute for media if you want light interaction, but I've often
wondered if it were possible to implement more flexible fogs, i.e.
cylindrical and spherical ground fogs, and perhaps even fogs restricted to
particular volumes (like an isosurface contained_by). It would be a very
useful and quick alternative for many special effects which would otherwise
require media, especially simple glowing effects and atmospheric haze. Such
features would definitely be high on my POV-Ray wish list for future
versions (hint hint!) - any opinions, anybody?
Bill
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Bill Pragnell wrote:
> Right, thanks to DKB's precision-tweaking, here's a more accurate Ringworld.
> The camera is now a mere mile (about 5000ft) above the ring floor, and the
> clouds are ten miles up (still a little high, I know, but close enough).
> The view is from roughly halfway to the rim from the ring midplane, as
> evidenced by the appearance of the arch (Thomas, I agree, this angle is
> much more dramatic!).
>
> Also in the foreground (relatively speaking - it's still over 15,000 miles
> away!) is Fist-Of-God mountain, approx 1000 miles high.
>
> I'm pretty happy with this, although I might tweak the clouds a little: the
> shiny scrith peak of the mountain is slightly obscured, and the immediate
> foreground is in shadow. Any comments or criticism welcomed!
>
> Render time: ~3 hours, mostly the mountain isosurfaces.
>
> Bill
>
>
> ------------------------------------------------------------------------
>
Nice picture.
Chris Cason says he'll include my change in the next beta version of
POV-Ray.
David Buck
Post a reply to this message
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Bill Pragnell nous apporta ses lumieres en ce 2005-11-01 06:15:
> Right, thanks to DKB's precision-tweaking, here's a more accurate Ringworld.
> The camera is now a mere mile (about 5000ft) above the ring floor, and the
> clouds are ten miles up (still a little high, I know, but close enough).
> The view is from roughly halfway to the rim from the ring midplane, as
> evidenced by the appearance of the arch (Thomas, I agree, this angle is
> much more dramatic!).
>
> Also in the foreground (relatively speaking - it's still over 15,000 miles
> away!) is Fist-Of-God mountain, approx 1000 miles high.
>
> I'm pretty happy with this, although I might tweak the clouds a little: the
> shiny scrith peak of the mountain is slightly obscured, and the immediate
> foreground is in shadow. Any comments or criticism welcomed!
>
> Render time: ~3 hours, mostly the mountain isosurfaces.
>
> Bill
>
>
> ------------------------------------------------------------------------
>
If the surface gravity is aroung 1G and the air pressure at ground level is similar to
ours, then
about 90% of that mountain is in vacuum! We have satellits orbiting at around 100 Km
over our heads,
about 2h period if I'm not mistaking.
As a side tough, when you get close to the edges, you should have the impression of
climbing. You
get a gravitational pull toward the midplane of the ring. As you move away from the
middle, there is
more and more mass behind you, and less before you.
--
Alain
-------------------------------------------------
Dogs crawl under gates, software crawls under Windows.
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Alain wrote:
> If the surface gravity is aroung 1G and the air pressure at ground level
> is similar to ours, then about 90% of that mountain is in vacuum! We
> have satellits orbiting at around 100 Km over our heads, about 2h period
> if I'm not mistaking.
> As a side tough, when you get close to the edges, you should have the
> impression of climbing. You get a gravitational pull toward the midplane
> of the ring. As you move away from the middle, there is more and more
> mass behind you, and less before you.
>
renember that "Ringworld" is a novell, so everything is possible. The
mountain called "fist of god" is a bullet hole left by an asteroid
impact which stretched the material the ring was made of. So it was
never ment to be populated, and there is no reason why the top shouldn't
be in vaccum.
The effect of gravity is negletable towards the radial acceleration if
you look up the dimensions of the ringworld. The ring itself is rather
fragile from far away and the construction is only possible due to
introduction of a new (yet unkown) super stable material.
... dave
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> Alain wrote:
The
> mountain called "fist of god" is a bullet hole left by an asteroid
> impact which stretched the material the ring was made of.
I'n not sure the shape of the mountain makes sense from a materials property
perspective.
If the scrith were more elastic than brittle (e.g. rubber), you would expect
the material to rebound some after the meteorite passed through. So the
shape of the mountain would be more like a torus, or ripples on a pond.
If the scrith were more brittle than elastic (e.g. wood), you would expect
cracks and faults radiating out from the exit hole, with possibly some of
the slower-moving bits falling back to the surface.
On the other hand, if the material were purely plastic (e.g. clay or metal),
it _might_ deform like the picture, but I suspect the slope of the mountain
would be much shallower, and the shape of the top more flared out.
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Wasn't it Alain who wrote:
>As a side tough, when you get close to the edges, you should have the impression
>of climbing. You
>get a gravitational pull toward the midplane of the ring. As you move away from
>the middle, there is
>more and more mass behind you, and less before you.
Bit the scrith has very low mass, so the gravity caused by the mass of
the ring material is low.
I did some calculations based on the Ringworld parameters given here:
http://www.alcyone.com/max/reference/scifi/ringworld.html
If you treat the Ringworld as an infinite plane, then the gravitational
force from its mass works out at about 1.4*10^-9 g.
I guess that the gravity inside a hollow cylinder may well be much lower
than that, in the same way that the gravity inside a hollow sphere is
zero, due to the pull of lots of mass far away above you cancelling out
the pull from relatively small amounts of mass nearby. So 1.4*10^-9 g
would be an upper bound to the gravity that would be felt by someone in
the midplane if the Ringworld were not spinning.
For comparison, if you stand on the Earth in a location close to where
there's a salt dome or a basalt inclusion, a typical gravitational
anomaly would be about 10^-6 g and you need a sensitive gravimeter to
detect the effect.
--
Mike Williams
Gentleman of Leisure
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"Joanne Simpson" <cor### [at] onewhiteravencom> schreef in bericht
news:web.43683abfe9e218d9dc45bc820@news.povray.org...
>
> On the other hand, if the material were purely plastic (e.g. clay or
metal),
> it _might_ deform like the picture, but I suspect the slope of the
mountain
> would be much shallower, and the shape of the top more flared out.
>
>
Now, that's interesting Joanne! From a different perspective (the
measurements of Fist-of-God on the Ringworld map in Ringworld Engineers), I
come to the conclusion that the mountain should have the shape of a shield
volcano, i.e. very flat.
Consider: The *base* starts almost at sea-level and gives it a radius of
150,000 miles. The slopes are gentle until an altitude of about 80 miles.
The final *cone* has a radius of 25,000 miles and ends at 1000 miles
altitude.
If you draw or model this you get a very flat object, with only the very top
perhaps flaring upwards. I even suspect that the mountain is so huge that it
would hardly be *visible* from the ground! in contradiction with what Niven
writes in fact...
Bill, what do you think? Do you agree with my measurements?
Thomas
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"Thomas de Groot" <t.d### [at] internlnet> wrote:
> measurements of Fist-of-God on the Ringworld map in Ringworld Engineers), I
> come to the conclusion that the mountain should have the shape of a shield
> volcano, i.e. very flat.
Yes, I would agree with that. However, the map in Ringworld Engineers is
almost certainly fan work and not necessarily in line with what Niven had
in mind.
> If you draw or model this you get a very flat object, with only the very top
> perhaps flaring upwards. I even suspect that the mountain is so huge that it
> would hardly be *visible* from the ground! in contradiction with what Niven
> writes in fact...
I go with Niven! His description of the mountain is very brief. He says that
it is "roughly conical" - nobody would describe a shield volcano as conical
except in the strictest possible sense (this is prose, not a mathematical
definition!). Natives for 100,000 miles around can see the mountain
clearly, indicating a distinctive, dramatic look. Also, Louis refers to the
top as a 'crater' quite early on. I used the mental picture I formed when I
first read Ringworld (over 10 years ago) - which was a steep, conical
volcano like Mt Ngauruhoe in north NZ. This doesn't of course preclude it
flattening out towards the base - which mine does, to a small degree.
As to whether it's visible - well, now we have the higher-precision
pov-engine we can find out. Make an atmospheric fog ~50 miles deep and put
your version of the mountain in it. Then look at it!
Bill
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