We need a new texture for Neptune

[Bob Hegwood]

Just a thought... In the interest of "education of the masses", maybe you could add the "invisible" rings to the existing image by using a dot-dot-dot or dash pattern?

Looks like I already have...

Take care, Bob

[don]

Cool! ... Looking forward to seeing how you represent them. Little happy faces with sunglasses maybe?

Non-astronomer folks (like me) can learn soooo much from your educational scripts. It's amazing, and eye-opening. Thanks again for writing them Bob!

[granthutchison]

Okay, I believe you... But now I'm really confused. If that's the case, then why do the *current* Neptune Ring textures (The ones you approve of as far as I know) contain the thick layers of dust between the Le Verrier Ring and the Adams Ring?

I guess you're using someone else's rings. The distribution texture shows only Adams and Le Verrier, with complete transparency between.

I just thought that if the rings *do* exist, then they need to be shown somehow. Does that make sense?

As I say, it's up to you ... it's your script. We're trying hard in the Celestia core package to show people what they'd actually see, within the limits imposed by Celestia as it develops ... although some day Celestia may also contain switches that allow you to tune up your sensitivity to light, or to switch to different wavelengths. And there are already oodles of add-ons showing people stuff they couldn't see with their naked eyes - every single one of the nebula billboards I've seen, for instance.

But then again, you've confused me some more. If Jupiter's Ring system is so dim, then how did Celestia get a texture for it? I certainly didn't create it. If I remember correctly, Praesepe contributed that piece of the Solar System. How was it contributed if their was no picture of it to go by?

You'd need to ask Praesepe how he created the specific add-on. There are images of Jupiter's rings, generated more or less the same way as the Neptune image you show above. Here's one:

Such views are taken from "behind" Jupiter, inside its shadow cone, so that the only light getting to the camera is the faint forward-scattering from Jupiter's rings, and often (in wider views) a glimmer of light scattered by its upper atmosphere, too. But the Jovian ring add-ons I've seen are just smooth semitransparent pngs, with their Inner and Outer limits taken from tables like the one you referenced earlier in this thread ... no image-processing required.

Grant

[don]

Maybe in addition to having an AlternateSurface definition, Celestia could also offer an AlternateRing definition? It would be very interesting to be watching a script and then have the two textures switched between, so folks get a good idea of how long-exposure photography really brings out things that we can't see with our human eyes.

[Bob Hegwood]

I guess you're using someone else's rings. The distribution texture shows only Adams and Le Verrier, with complete transparency between.

Okay, could you please point me to a file so that I can download and
use the "official" ring texture for the script? Every texture I have thus
far for Neptune's Rings has the same layer of dust between the two
"visible" rings.

Thanks, Bob

[don]

Bob,

I just e-mailed you the file used in the current (1.3.2 pre7) Windows release. I do not see any "dust" with this file on my system. Hope this helps.

[Evil Dr Ganymede]

I didn't even notice Neptune HAD a ring system in Celestia til I looked because of this thread. I can just see two tiny black lines and that's it.

As for the Voyager images - it's worth remembering that ALL of the Voyager 2 Neptune images had a very long exposure - the exposure on the ring pictures was even longer than normal to make them visible.

[granthutchison]

Okay, could you please point me to a file so that I can download and use the "official" ring texture for the script? Every texture I have thus far for Neptune's Rings has the same layer of dust between the two "visible" rings.

It's just the original file that came with the Celestia download. If you haven't backed it up, then you can get it off the CVS tree here: http://cvs.sourceforge.net/viewcvs.py/celestia/celestia/textures/lores/neptune-rings.png
If you've edited the Rings definition in solarsys.ssc, you should also restore the original settings to go with the texture:

Code: Select all

   Rings {
      Inner  53150
      Outer  62947
      Texture "neptune-rings.png"
   }

You can check the final arrangement by going to Despina ... when you zoom back a little you should find it's shepherding the inner Le Verrier ring.

Grant

[granthutchison]

I didn't even notice Neptune HAD a ring system in Celestia til I looked because of this thread. I can just see two tiny black lines and that's it.

Good-o. That's the effect I was aiming for. I had to increase the opacity of the ring texture considerably (otherwise the rings would be too dim to show up at all with the limited range of a computer monitor), which has led (as Fridger has pointed out to me) to the generation of an awkward ring shadow that wouldn't be detectable in reality.
In future versions I may ramp the opacity down again to the limit of vision - we really want something that shows up when you're close to the ring, but otherwise not at all.

Grant

[Bob Hegwood]

Grant,

Sorry about that...
I don't understand where my texture for the rings came from, but I was almost positive that it was from the original distribution.

I installed them again, and you're absolutely correct. They look as they SHOULD look according to everything you've told me, and from what I can find on the web.

Many thanks for the information.

I'll go ahead and use these in the script since I'd prefer that they be as accurate as possible. I'll probably just add some explanatory text to identify the portions of the rings which cannot be seen in a normal setting.

As for the rings of the other planets, I'll simply modify the scripts a bit to explain the limitations of the effects.

Very educational this... Thanks muchly for the information.

Take care, Bob

[Bob Hegwood]

Maybe in addition to having an AlternateSurface definition, Celestia could also offer an AlternateRing definition? It would be very interesting to be watching a script and then have the two textures switched between, so folks get a good idea of how long-exposure photography really brings out things that we can't see with our human eyes.

Now THERE's a good idea... That way we could tour the place and show
both what's visible, and what's actually there. I like the idea. Anybody else?

I'll post this up in Feature Requests too.

Thanks, Don.

[danielj]

The texture without the GDS,altough is 2k,is more pixelated and less realistic.Anyway,why don't we can assume that Hubble don't have suficient resolution to see a spot in Neptune.Why we can be sure what happened with the blue planet only based in Hubble's perspective,which is limited?

I'm sure a lot of people have already created alternate "current" Neptune textures but for those who haven't and want one, here's one (2K) made with a simple photoshop cloning hack:

http://members.aol.com/celestiastuff/neptune_current.zip

Don't know how realistic it is since Neptune seems to be a pretty dynamic place but at least the Great Dark Spot is gone. Here's some images to show the difference:

With Dark Spot:


Without Dark Spot:


The install.txt file within the zip archive has all the important stuff.

Dave

[Bob Hegwood]

The texture without the GDS,altough is 2k,is more pixelated and less realistic.Anyway,why don't we can assume that Hubble don't have suficient resolution to see a spot in Neptune.Why we can be sure what happened with the blue planet only based in Hubble's perspective,which is limited?

Daniel,

Trust me, the Great Dark Spot is no longer there...

If you don't believe me, then spend two weeks researching the topic via
NASA and every OTHER agency I could think of...

Hubble HAS in fact, found other, smaller dark spots on various occasions, but these
too had a limited lifetime. But if you'd rather, I guess you can assume anything
you want to.

Take care, Bob

[Bob Hegwood]

Daniel,

More information for you...

Links:

http://antwrp.gsfc.nasa.gov/apod/ap960508.html
http://oposite.stsci.edu/pubinfo/gif/Neptune.txt
http://members.aol.com/_ht_a/bobalien99/neptspot.htm
http://www.planetary.org/learn/solarsystem/neptune.html
http://www.seds.org/hst/NeptDS.html

Hubble can resolve features on the planet down to a resolution of 625 square miles.

Hope that helps.

Take care, Bob

[DaveMc]

The texture without the GDS,altough is 2k,is more pixelated and less realistic.

Daniel,

The 2K texture without the GDS was made from the same 2K texture with the GDS and saved with the same compression, resolution, etc. so it is no more or less pixelated than the original. As far as realistic, who the heck knows!

Dave

[Bob Hegwood]

Dave,

I don't give a damn whether it's pixelated or not... The revised texture
looks GREAT on MY machine. As I mentioned before, I'm now using it in
the latest script I'm working on, and I can tell NO difference in your
texture and the old one. (Except that the GDS is gone!)

Thanks again, Bob

[TERRIER]

As far as realistic, who the heck knows!
Dave

Just digressing slightly but I see someone had a go at animating Neptunes clouds during a short scene in the mediocre film Event Horizon which was shown on the 'good old' BBC, over the Easter holidays.

[Bob Hegwood]

Terrier,

I remember that movie... How do you go about simulating a 2000 kph wind though?

Take care, Bob

[TERRIER]

Bob,

A grisly film....

How do you go about simulating a 2000 kph wind though?

....but going from my bad memory, I think Neptune had a reasonable sized hurricane !

regards
TERRIER

[gradius_fanatic]

ya know....I think it's really a shame to have a much known feature of neptune to dissapear like that. But hey, that's neptune for ya!