T00fri's Titan @ Celestia

[t00fri]

Fridger:

Your skill in coloring Titan using more detailed surface layers is obviously excellent. I will defer to your effort over mine. I am ready to package and zip up my most recent Educational Activity, which covers the planetary spacecraft, including Huygens. I want to include the latest texture of both Titan and its clouds, and of course, Jestr's great Huygens descent add-on.

When will your new textures for Titan's surface, its clouds, and its haze be available for download? Also, will the cloud layer have any transparency, as you once suspected it might?



Frank

Frank,

glad you liked the modifications above. I can see two factors that make a precise schedule difficult:

1) The texture I used above is largely based on an upgrade of my default Celestia texture as recently done by Steve Albers. He had asked my permission for using my texture and added in the latest hires projections from the Titan flyby. So I guess before you package things, his consensus should also be obtained.

2) The coloration I did above was just a 5 minute affair which also means that I am usually not satisfied with such "quick shots"... (GIMP2 has complete, ready to use color mapping macros). Before I release a "next-generation" default Celestia texture of Titan, I want to see more official surface color images and precise statements about the filtering etc that has been used.

On the other hand, as long as Steve is 'd'accord', you are always welcome to use my work from a preliminary stage.

It would also be really nice to have /all/ available hires shots of titan incorporated into the texture before releasing it...

We do have clear photographic evidence that in /visual/ light and seen from a distance, Titan's cloud cover is practically not transparent. So for now, the most consistent approach within Celestia seems to be un-transparent clouds along with a detailed surface texture that becomes visible after toggling the I-key. The conceptional problem remains (as detailed higher up), that the true visible surface colors require in principle the presence of the haze (that acts as a complex color filter)!

Bye Fridger

[fsgregs]

Fridger:

I'll get Steve's approval today. Assuming he has no problem (why do an add-on if people can't download and use it??), where can I get your preliminary new textures for Titan's surface and its clouds? Could you add it to a site for download please (knowing in advance that you probably will alter it later)

Thanks

Frank

[t00fri]

Fridger:

I'll get Steve's approval today. Assuming he has no problem (why do an add-on if people can't download and use it??), where can I get your preliminary new textures for Titan's surface and its clouds? Could you add it to a site for download please (knowing in advance that you probably will alter it later)

Thanks

Frank

I have uploaded the preliminary modified surface texture to my TextureFoundry. It's 2k. Note Steve's texture needs an offset for being used in Celestia. My colored version is properly alligned, of course. The cloud cover is unchanged relative to the default Celestia-1.3.2 one which I presume you got.

The texture is great together with Jestr's add-on, since the Huygens landing site is marked and /hires/ in this region. You can land there any time ...

Here is the texture:

http://www.shatters.net/~t00fri/images/titan2k-col.jpg

Enjoy,

Bye Fridger

[hank]

I don't suppose anyone has built a VT using the Huygens DISR images yet...

- Hank

[t00fri]

I don't suppose anyone has built a VT using the Huygens DISR images yet...

- Hank

Why are you asking about VT's? It's all pretty much low resolution material...

Bye Fridger

[fsgregs]

Fridger, thanks for the texture. Its great. But now I'm confused.

The texture is great together with Jestr's add-on, since the Huygens landing site is marked and /hires/ in this region. You can land there any time ...

I have Jestr's new Huygens descent add-on dated January 4, and although he does have a landing site, there is no "locations" file for it, and no "hires" textures. Is there a new add-on he just did that I don't have?

Frank

[t00fri]

Fridger, thanks for the texture. Its great. But now I'm confused.

The texture is great together with Jestr's add-on, since the Huygens landing site is marked and /hires/ in this region. You can land there any time ...

I have Jestr's new Huygens descent add-on dated January 4, and although he does have a landing site, there is no "locations" file for it, and no "hires" textures. Is there a new add-on he just did that I don't have?

Frank

Frank,

sorry you misunderstood:

There is only one Cassini/Huygens add-on by Jestr.

The new texture you just downloaded has the environment of the landing site in /hires/. Look at the lhs of the texture and you will understand!
You may enter 'huygens landing site' into the command line and hit G. This gets you to Titan's surface right close to Huygens. Then move up a few hundred meters and soon you will see the name 'Huygens Landing site'. There is no locations file. You may also /select/ that site, which is practical.

Bye Fridger

[fsgregs]

Hi Fridger:

Thanks for the reply but I must still be dense.

The new texture you just downloaded has the environment of the landing site in /hires/. Look at the lhs of the texture and you will understand!

I downloaded the 2k texture and replaced the existing Titan with it. I also have Jestr's magnificent add-on running.

What does

The new texture you just downloaded has the environment of the landing site in /hires/. Look at the lhs of the texture and you will understand!

mean? What is "Ihs"? The texture is 2k and has no "hires" detail or hires image that I can find.

I am also confused about Jestr's add-on in one regard. On my computer at least, the descent model comes down to Titan and lands approximately 48 km from the location of Jestr's "Huygens Landing Site". I am not faulting Jestr at all on this. It is simply what the xyz file for the descent model is coded to do. I tried to move those coordinates so that the model comes down next to the landing site, but it turned out badly. Too many variables in the xyz file to manipulate. Instead, I was able to move the landing site long/lat so that it at least is positioned next to the Huygens descent model. Presumibly, this would be a desired effect. I was also able to fix the jerking around that the model does during descent due to rounding problems in the xyz file, without affecting accuracy. I sent both corrected files to Jestr, but ...

Do you all see the same thing occurring, or is my computer screwy? Is it preferable to have the two models 48 km apart, or would my edit of the landing site be something others would prefer?

Frank

[t00fri]

Hi Fridger:

Thanks for the reply but I must still be dense.
...
What does

The new texture you just downloaded has the environment of the landing site in /hires/. Look at the lhs of the texture and you will understand!

mean? What is "Ihs"? The texture is 2k and has no "hires" detail or hires image that I can find.
...

Wuff...

lhs=left hand side, an acronym that /all/ of my anglosaxon colleagues are constantly using...



Bye Fridger

PS: If it's still not clear, I give up....

[fsgregs]

WELL!!!



Thanks

Frank

[Matt McIrvin]

...So, apparently one of the problems the Huygens probe had was that its Sun sensor couldn't get a lock on the Sun's position once it was inside the haze layer, which meant that the people piecing these pictures together into mosaics don't have good orientation data.

This may not have any bearing on the burning question of whether a person could point out the Sun from the surface of Titan, but we now know that at least one machine couldn't pick it out...

[t00fri]

...So, apparently one of the problems the Huygens probe had was that its Sun sensor couldn't get a lock on the Sun's position once it was inside the haze layer, which meant that the people piecing these pictures together into mosaics don't have good orientation data.

This may not have any bearing on the burning question of whether a person could point out the Sun from the surface of Titan, but we now know that at least one machine couldn't pick it out...

Matt,

were did you read that?

Thanks,

Bye Fridger

[PlutonianEmpire]

Hi all,

well, as a next step to improve my Titan texture in Celestia-1.3.2 might be to start from Steve Albers' recent 2k texture, which is based in part on the texture I made for Celestia:

http://laps.fsl.noaa.gov/albers/sos/sos.html

By colorizing that improved grayscale texture with the surface color spectrum from the first colored surface image (ESA site), we get a next approximation to reality, as you may judge below.

There is a glitch, however:

The apparent surface colors strongly depend on the colors of the atmospheric haze. Yesterday's color photo from ESA

was taken in the presence of the haze, of course. In Celestia, we can exhibit Titan's surface only, after 'clicking away' the haze (i.e. toggling the I-key). So what is the appropriate color of the surface in Celestia??

I think it is most reasonable to colorize the surface texture according to realistic surface photos taken with a realistic sky coloration overhead...


The result then would look about like so in Celestia

<snip>

Bye Fridger

I just noticed--the top surface pic in this post is also seen on the first post. Except--at the bottom, it says: "Last edited by t00fri on Mon JULY 05, 2004 4:39 pm; edited 1 time in total"!!!

So how in the world did that pic appear BEFORE Huygens landed?!

[t00fri]

On my screen it says :

Last edited by t00fri on Sun Jan 16, 2005 19:46; edited 1 time in total

which is also when I did edit it.

Bye Fridger

[PlutonianEmpire]

Hmm...

Must be a compatibility problem with my computer.


In other news, I made my own (fictional) titan addon. 2 screenies.

For this one, I combined the titan and callisto textures, and did some recoloring.




How does it look? Any comments, tips?

[Michael Kilderry]

Very nice Titan PlutonianEmpire, I like the methane oceans. The cloud layer looks a tad thin though, you wouldn't be able to see the surface from underneath.

Michael Kilderry

[PlutonianEmpire]

Very nice Titan PlutonianEmpire, I like the methane oceans. The cloud layer looks a tad thin though, you wouldn't be able to see the surface from underneath.

You mean the layer is a bit close to the surface?

[t00fri]

PlutonianEmpire,

your "Titan" texture is a nice piece of graphical art, but I would not really want to call it "Titan".

1) Your bumpmapped surface elevations are way to high, as we know since quite a while from these radar topography measurements from the NASA-Cassini site:



2) Your surface colors look dramatic, but they disagree (in visible light) with the color photo we meanwhile have from the surface.

3) The clouds are too transparent (assuming visible light) and their colors and texture do not match the available photos.

While it is certainly fun to speculate graphically about possible alternative surface scenarios, according to my taste, the /known/ features should not disagree, if we want to name the object "Titan".

Bye Fridger