And now for something completely different...

[selden]

Daniel,

No, Ringworld and Rama are not related to one another.

Rendezvous with Rama was written by Arthur C. Clarke. (Later books in the series were written by Gentry Lee.) Rama was a 30 mile long alien spacecraft that flew through the solar system.

Ringworld and its sequels were written by Larry Niven. Ringworld was a megastructure orbiting another star, hundreds of millions of miles in diameter, somewhat larger than Rama Many people have had fun trying to describe why it couldn't work the way Niven originally described. In later books he described ways to avoid those problems.

Making a model that large which still has good surface detail is, shall we say, difficult, and thus a challenge.

[rthorvald]

The orbital model I made does have a separate cloud layer, but no atmosphere. Interesting idea to make a very flat atmosphere- doesn't it pop out of the back as well, though?

I am familiar with Banks??culture books and his orbitals, yes.

As for the atmosphere, remember that the outside of the ring is always in the dark; Celestia think each segment is a planet, and so it understands that the back of the ring should be in shadow. And so no light is rendered through the atmosphere on that side - in effect, it is invisible, at least if you position the atmosphere placeholder and size it properly. You can see some spillover at the rim walls, though.

how do you get the clouds to remain smoothly rendered on the inside of the ring?

By making the cloudmaps CMOD models instead of putting them in the atmosphere code.

Why Ringworld is the "holy grail" of sci fi modeling?

Of all the iconic scifi structures, it is the one most difficult to make for Celestia; noone has achieved something that looks remotely realistic yet.

- rthorvald

[t00fri]

Soon or later I always get back to the physics of it: Ringworlds, what keeps the atmosphere close to the "surface"? Why isn't it just blown away into space??

F.

[rthorvald]

what keeps the atmosphere close to the "surface"? Why isn't it just blown away into space??

There are walls... 1600 kilometer high rim walls on both sides.

On a side;
The story in the book takes place many thousand years after the Ringword builders has disappeared, so a lot of cultures has popped up all around the place that have no idea they are living on a ring. Exept for one, that was smart enough to get to the outside - where they found the ramjets that kept the thing stable. Naively, they popped them off to build spaceships And another concept i liked was the poor guy that decided to go find the base of the Great Arc...

- rthorvald

[MKruer]

what keeps the atmosphere close to the "surface"? Why isn't it just blown away into space??

There are walls... 1600 kilometer high rim walls on both sides.

- rthorvald

Actually its centripetal force + 1600 kilometer high rim walls.

[Reiko]

Just playing...
With something different.

I am sure all the other sci-fi geeks here recognizes this. It is sort of the
holy grail of fictional-celestia

I played around with Marc Griffith??s SSC file for it last night to see if it
was possible to do something real with it, and it is... This one has both a
workable atmosphere and clouds. The only problem is that the shadow
squares don??t cast shadows, and Marcs solution to that is less than
satisfactory when one goes 3D with the surface.

Another problem is, of course, that the scale of the thing is so immense
Celestia is unable to assemble it without seams between the many
segments one will need - i made just one, very quickly as a proof-of-
.concept, and duplicated it up - the seam is invisible from space, but
becomes prominent if i fly beneath the clouds...

If i get the time, i might go forward with it later, but it would be a big
job - and a very memory-taxing work... Just the Great Sea alone is a
project in itself.



And, a comparison: the little bright dot in the red circle is our Earth...:


- rthorvald

That is neato! Makes me want to read Ringworld again.

[t00fri]

what keeps the atmosphere close to the "surface"? Why isn't it just blown away into space??

There are walls... 1600 kilometer high rim walls on both sides.

On a side;
The story in the book takes place many thousand years after the Ringword builders has disappeared, so a lot of cultures has popped up all around the place that have no idea they are living on a ring. Exept for one, that was smart enough to get to the outside - where they found the ramjets that kept the thing stable. Naively, they popped them off to build spaceships And another concept i liked was the poor guy that decided to go find the base of the Great Arc...

- rthorvald

The walls were missing in the Celestia add-on. That's why I had a physics problem...

F.

[rthorvald]

The walls were missing in the Celestia add-on. That's why I had a physics problem...

Aha. But they aren??t missing in my little demo; this is what i made:


There are several problems with this model, though: for one, the walls are extremely exaggerated; in reality, they should not be visible at all at this scale.

The biggest problem here, and in the earlier attempts i have seen, is that the size of it is impossible to grasp. For example, any surface features at all should be invisible at the scale i show here - at such a distance everything should be a bland green/blue pattern, and resolving anything at all should only be possible when you are so close the segment more or less is everywhere around you. In this picture we are looking at a surface area comparable to a million Earths.

Here is someone that has made a try at it:
http://www.squareshadow.com/graphics/ringworld/rw5.html

- rthorvald

[Chuft-Captain]

What would be required to do this properly is VT's on model meshes.

(I haven't worked it out, but perhaps up to 30 levels would be required )

( EDIT: ...and Terabytes of RAM )

[Cham]

You guys gave me the mood to make some SF stuff of my own. So I used the day to build this huge space station :

[ElChristou]

You guys gave me the mood to make some SF stuff of my own. So I used the day to build this huge space station :

Sympa!
What about some emissive part?

[Chuft-Captain]

You guys gave me the mood to make some SF stuff of my own. So I used the day to build this huge space station :

Can't view your images Cham... something wrong (overloading perhaps) at freeimagehosting.net ???

[Cham]

Can't view your images Cham... something wrong (overloading perhaps) at freeimagehosting.net ???

These free servers are having difficulties all the time, apparently. Sometimes, the pictures are unavailable, or it may be really slow. I didn't found any fast and reliable free image server yet.

[selden]

An inappropriate posting by DanielJ and additional inappropriate responses have been removed.

DanielJ has been formally notified of our displeasure.

[Cham]

Adding more details, and a fast rendering in the modeler, can give a nice feel (without shadows, just to compare with Celestia's rendering. I'm also testing some free picture host) :

(click to enlarge)


It could be cool, to recreate in Celestia the typical classic scenes of Chris Foss :

http://en.wikipedia.org/wiki/Chris_Foss

http://bricabrac.perso.cegetel.net/chrisfoss.html

http://www.altanen.dk/Gallery-Main.htm

[chris]

Adding more details, and a fast rendering in the modeler, can give a nice feel (without shadows, just to compare with Celestia's rendering. I'm also testing some free picture host) :

(click to enlarge)

Nice use of non-white specular color to give a metallic effect.

--Chris

[ANDREA]

It could be cool, to recreate in Celestia the typical classic scenes of Chris Foss

I agree, Cham.
I'm the fortunate owner of a copy of "21st Century FOSS", edited on 1978 by Dragon's Dreams Book, a wonderful example of fantasy and drawing ability.
If you haven't it, and if you need, I can copy some images for you.
Bye

Andrea

[rthorvald]

A little further:
Here is a zoom-in on the Great Oval Ocean. The bottom pic shows the
underside, and if you look at the opposite side, you will see (barely) the
second Great Ocean there.

The textures are a hasty job with the clonebrush, not good for a release,
but workable for a demo. There are no clouds in these pics, but they
would need to be developed too.

The Oval Ocean is 2k, everything else is 1k. One would need the
equivalent of a 16k map (in a strip) to make this look good, and painting
that is weeks of work that i am not going to do right now. But it is fun to
build the SSC setup and the models. Of course, one will also need hi-res
models of the area around the Fist-of-God mountain and a depiction of
the arrival of the Needle of Inquiry.



- rthorvald

[Reiko]

This looks really great!

Have you considered putting the continents of the earth in one of those oceans like in the book?

[rthorvald]

Have you considered putting the continents of the earth in one of those oceans like in the book?

The maps of Earth and Mars must of course be in the ocean, yes, but at the distance of the closest image here, the Earthmap would be just a pixel...

- rthorvald