Closeups of Saturn's Rings - 3 versions

[Chuft-Captain]

(Click the images for full-size...)

A:

B:

C:

Preferences?
Comments?

[Goofy]

Hi Chuft-Captain.
Your ring textures are interesting, and I would like to check the B and C with Cassini's originals.
Will you upload them somewhere, please?
Bye

Goofy

[t00fri]

Good Saturn rings are not easy!

About 5.5 years ago, I made a nice texture for the lit side of the rings in high resolution (Ciclops data). See here the discussion from 3.5 years ago:
http://www.celestiaproject.net/forum/viewtopic ... 80&start=1
and about 5.5 years ago, when it all started:
viewtopic.php?f=2&t=11559&st=0&sk=t&sd=a&hilit=saturn+rings&start=19

The transparency across the rings (texture's alpha channel!) is determined and adjusted from earthbound observation of the passage of some star of known luminosity across the rings. Somewhere I have the citation of this amazing paper...

So far the unsatisfactory part concerns the unlit side of the rings that looks rather dull black with my texture. ChrisL made some shader experiments at the time (see quote above) to improve the view. In any case some hightech means are required to get a satisfactory result.

Fridger

[Chuft-Captain]

Goofy,
It was a little bit of a trick question...
B is a crop of the NASA composition, here: http://www.nasa.gov/mission_pages/cassini/multimedia/pia06193.html
A is the 1.6.1 default 1K texture, from a similar viewpoint in Celestia,
and C is my 4K version.

So you can compare A and C directly with the Cassini version (B).

The transparency across the rings (texture's alpha channel!) is determined and adjusted from earthbound observation of the passage of some star of known luminosity across the rings. Somewhere I have the citation of this amazing paper...

For this first cut, the transparency in [C] is based on: data from the occultation of 28 Sgr.
I would be interested to read that paper if you can track down the reference. (Although the alpha channel is the least of the problems at this point.)

So far the unsatisfactory part concerns the unlit side of the rings that looks rather dull black with my texture. ChrisL made some shader experiments at the time (see quote above) to improve the view. In any case some hightech means are required to get a satisfactory result.

I agree. For the sake of this exercise, I took the color channels from the un-illuminated side of the rings: http://photojournal.jpl.nasa.gov/catalog/PIA08389 which also gives unsatisfactory results (but in the opposite circumstances). As you suggested, there is no easy solution to this, only compromises. (short of more sophisticated shaders).

For further comparison, here are the views from Cassini on the date of the NASA imagery (06 Oct 2004). Again (B) is the NASA composite for comparison with the view in Celestia using (A) the 1K default texture, and (C) my new 4K version. (The issues are more obvious in these images...)

A:

B:

C:

[t00fri]

CC,
I am quite sure it was the 28 Sgr paper you mentioned. It's also cited in the Celestia-README. Unfortunately most people need to pay 31$ for reading it. Didn't find a free option. I can read it through my laboratory though, but no sending around, of course.

Fridger

[abramson]

Someone over at Arizona has it on line, though
http://www.lpl.arizona.edu/~umpire/professional/papers/1067a.pdf

[Chuft-Captain]

Thanks for sharing that link Guillermo.

[Chuft-Captain]

The latest iteration, using color channels from the illuminated side:

[Danny Lorraine II]

where can i get those textures? i might need them for my celestia . thanks