The Rings of Uranus

Bob Hegwood · Post #1by **Bob Hegwood** » 27.01.2004, 04:58

Sorry, don't know if this is a bug or not, but I simply cannot use another texture for the rings of Uranus.

If I try to use any other image (other than the lores image which is included with Celestia in the lores folder) to display the rings of Uranus, all I see is a familiar white, featureless oval. This is the same effect you get if you have mis-named your texture reference in "solarsys.ssc" and I can assure you that I have not.

You will also get this effect if your texture is not to be found in one of the "Celestia\Textures" folders, and again, I can assure you that the texture I'm trying to use is where it is supposed to be.

Is there something special about Uranus with respect to its ring system?

I'm simply trying to use a different PNG file to display the rings. I'm trying to use a different texture because the one that is included with Celestia is just barely visible. And I do mean barely. I can see only a single pixel's width of light where the ring system should be located. This can't be right can it?

For your further edification, I also tried to use the Saturn Rings texture - which DOES show up around Saturn - just to see if it would show up around Uranus, but I still got the same effect. Why would a texture work on one planet and not on another one?

What gives?

Thanks, Bob

Post #2by **selden** » 27.01.2004, 12:11

Bob,

The real rings are essentially too faint to be seen by the naked eye. The rings provided with Celestia are almost right

Unfortunately, Celestia v1.3.1 no longer scales ring images. You have to use one that is no wider than the size of the texture buffer provided by your system's OpenGL driver. Look at Celestia's Help "OpenGL Info" menu. It has a line that says "Max Texture Size".

(I'll add this to the "Preliminary User's FAQ")

Bob Hegwood · Post #3by **Bob Hegwood** » 27.01.2004, 15:03

Selden,

My Maximum texture size is 1024 which is why I'm always having to downsize those great-looking 8k textures so that I can use them.

But, this has not changed since I've been using Celestia. If I try to use a Uranus Ring texture that is 1024 x 2 I should *still* be able to do that should I not?

The textures I'm using for Jupiter's Rings, Saturn's and Neptunes are all working okay using the 1024 x2 convention. The only one I can't get to work is Uranus.

I'll play around with it some more, but this is becoming a frustrating excercise. Are you telling me that Celestia no longer handles rings as it did in 1.3.1 Pre11?

Thanks, Bob

Bob Hegwood · Post #4by **Bob Hegwood** » 27.01.2004, 15:08

One other note for you, Selden...

It appears to me that the rings ARE capable of being seen with the eyeballs. Have a look here - http://ringmaster.arc.nasa.gov/uranus/earthbased/PIA01280.html

Okay, my mistake, apparently the rings are "as black as coal."

In any case, I wish to be able to SEE them. :cry:

Take care, Bob

Post #5by **selden** » 27.01.2004, 15:19

Bob,

Did you try to use the same ring image file for both Saturn and Uranus?
I'd check again for typos, and cut-and-paste exactly the same text from the Saturn definition into the Uranus definition.

If the ring texture is 1K, and 1K textures work for other planets with rings then my guess as to the cause of your problem was wrong.

FWIW, as it says in the caption, the picture on "ringmaster" is false-color infrared. Also...

Image processing has been used to brighten the rings around Uranus so that astronomers can study their structure. In reality, the rings are as dark as black lava or charcoal.

That's not exactly what I'd call "naked eye visibility"

But as you say, it's irrelevant to your problem.

Bob Hegwood · Post #6by **Bob Hegwood** » 27.01.2004, 16:01

Sorry Selden,

I guess we were typing our messages to each other at the same time. I was editing my previous messages when you left your latest one on the desktop here.

To re-iterate, I have tried to use the same Saturn texture which DOES display quite nicely on Saturn - on the Planet Uranus, and all I got was the featureless white oval we're all so familiar with by now.

I did NOT try to change the SSC's dimensions of the rings though, so I'll give that a try next.

Thanks, Bob

Bob Hegwood · Post #7by **Bob Hegwood** » 28.01.2004, 03:22

Selden,

Still don't know what the problem is here...

I have had to re-install Celestia in order to display even the original Uranus rings. I suppose that I will just not touch that planet for a while. :wink:

Is weird though. I don't understand why just this one planet has problems with the rings.

Take care, Bob

Bob Hegwood · Post #8by **Bob Hegwood** » 28.01.2004, 19:32

Selden,

One more piece of information on the Uranus Rings problem...

After I installed 1.3.2 Pre1, this problem simply went away. I can now use *any* ring system I want to with Uranus and it displays itself perfectly.

I have *no* idea what was happening with 1.3.1-1, but the upgrade fixed this problem.

Just FYI.

Thanks, Bob

Bob Hegwood · Post #9by **Bob Hegwood** » 02.02.2004, 18:06

Here we go again...

I don't know what the difference is, but Uranus just will NOT let me use another ring texture. All I get is the featureless white oval again.

What is going on with Uranus? Is there something special about that planet and its rings? I've looked at solarsys.ssc, rings.vp, rings_arb.vp, and ring_locs.ssc all to no avail.

Does no one else have this problem? And by the way, I cannot get the original lores uranus-rings.png to work either.

What gives? If I reinstall Celestia, (1.3.2 Pre1) I get the rings back again. Just thought I'd let you know... AGAIN!

Thanks, Bob

Post #10by **selden** » 02.02.2004, 19:08

Bob,

I have to believe that the image file Celestia is trying to use for the rings of Uranus isn't the file you think it is.

Exactly what does it say in the console log? (type a ~ to see it, arrow keys to scroll)

Post #11by **selden** » 02.02.2004, 19:49

Bob,

One quick check is to use the "hires" directory for your new ring image.

Restore the original, unmodified solarsys.ssc
Restore the original, unmodified texture image file "uranus-rings.png" to the folder \textures\lores\
Delete any texture image file named "uranus-rings.png" from the folder \textures\medres\

Put your ring png image file into Celestia's folder \textures\hires\
Make sure the image file is named "uranus-rings.png"
And make sure it actually is a .png file, not a renamed jpeg or dds file.

Start Celestia
GoTo Uranus
You should be shown the rings that come with Celestia (from the lores folder)
Type an R
You should see Celestia flash a message "High res textures"
You should be shown the ring file that you put into \textures'hires\

Look at the console log (~)
The last few lines should be

Loading image from file textures/medres/uranus-rings.png
Error opening image file textures/medres/uranus-rings.png
Loading image from file textures/lores/uranus-rings.png
Loading image from file textures/medres/umbriel.jpg
Loading image from file textures/medres/ariel.jpg
Loading image from file textures/medres/miranda.jpg
Loading image from file textures/hires/uranus.*
textures/hires/uranus.*: unrecognized or unsupported image file type.
Loading image from file textures/hires/uranus-rings.png

Bob Hegwood · Post #12by **Bob Hegwood** » 03.02.2004, 00:59

selden wrote:Bob,

I have to believe that the image file Celestia is trying to use for the rings of Uranus isn't the file you think it is.

Exactly what does it say in the console log? (type a ~ to see it, arrow keys to scroll)

Selden,

The file I am trying to use is EXACTLY the file I'm trying to use. It's where it's supposed to be, it's in the correct format, and it exists just like any other ring system file on my pc.

However, now that you've shown me how to follow the logic of the console, I managed to see that the problem lies NOT with the ring image, but with the image of the planet itself.

Don't know why, but the planet is displayed WITHOUT an image anywhere on my pc. I see a pretty greenish-blue ball, so I don't think to see if the PLANET image is a problem.

Well, that WAS the problem. Since I'm an idiot, I didn't even think to look at that. When I viewed the console log though, I saw that Celestia simply could not find the uranus.* image anywhere.

In short, Celestia could NOT find the planet image, and - even though the ring image was okay - it refused to show the rings.

Methinks I owe you a drink or two...

Come to think of it, I think I'm going to have a few now. Sheesh! :oops:

Thanks very much for explaining that console log thingy. That made it easy to find the problem. I don't know if I knew about that before, but I'll damn-sure remember it from now on.

Thanks again Selden. You don't get paid enough for this...

Take care, Bob

TERRIER · Post #13by **TERRIER** » 03.02.2004, 01:55

Bob

I s'pose in a way, this proves how boring and featureless the planet 'surface' of Uranus appears to be. (At least, going by the small amount we currently know about it)

This could be a good way of slightly cutting down the file size of Celestia, by not bothering with a Uranus planet texture.

:lol:

TERRIER

Bob Hegwood · Post #14by **Bob Hegwood** » 03.02.2004, 04:52

Hah!

Great idea Terrier... But then you'd never get to see the rings. :wink:

Let me tell you though, this was a REAL learning experience. I must have tried to get those rings to display for two whole days.

You're just about correct though, since I can hardly tell *any* difference in the way the planet looked.

Ah well... Now I know something more than I did.

Take care, Bob