Celestia Forums

Evening all,

I was just browsing/searching through some older posts on getting Titan's atmospheric coloring closer to reality. Did anyone arrive at a particularly good result? I know Runar and Fridger were both working on it at one point. Thanks...

I downloaded http://www.celestiamotherlode.net/catal ... don_id=805 and I'm fairly satisfied with the look of Titan with it.

*shrug*

buggs_moran wrote:Evening all,

I was just browsing/searching through some older posts on getting
Titan's atmospheric coloring closer to reality. Did anyone arrive at a
particularly good result? I know Runar and Fridger were both working
on it at one point. Thanks...

Titan (Celestia distribution) as well as his atmosphere/haze color is by
me. I have exploited all available visual, ~true-color photographic
imaging information.

So what's the problem?

I ALWAYS use the computer for coloration to be as precise as possible.
This means Titan's surface color is computer - derived from the
Huygens landing (color) photo. The atmosphere color is similarly
derived from available data. The only still not settled issue concerns
the naked-eye visibility of the purple-blue upper atmosphere color. I
have communicated with the lead scientist from the Titan imaging team
about this point. Even there the opinions were split...

The atmospheric parameters are from the data by the imaging team
published in their Nature article which they have sent me.


Bye Fridger

t00fri wrote:Titan (Celestia distribution) as well as his atmosphere/haze color is by me.
[...]
The only still not settled issue concerns the naked-eye visibility of the purple-blue upper atmosphere color

Let me add that the atmosphere colors in the Titan Add-Ons are Fridger??s, exept that i have added the upper blue.

- rthorvald

t00fri wrote:So what's the problem?

...The only still not settled issue concerns the naked-eye visibility of the purple-blue upper atmosphere color.

No big problem Fridger. I hadn't looked at any of these addons in some time and was just digging for them for the post below where I was making an image similar to one of Cassini's. I guess I was more specifically interested in the blue haze. After reading the posts I see why it is not included in the distribution.

http://www.shatters.net/forum/viewtopic.php?t=9702.

I guess the true problem would lie in the search for an addon that contained that haze layer.

buggs_moran wrote:I guess the true problem would lie in the search for an addon that contained that haze layer.

You mean like this?:


It isn??t exact as Celestia really don??t allow two atmosphere layers, but it
is a reasonable representation.

- rthorvald

buggs_moran wrote:

t00fri wrote:So what's the problem?

...The only still not settled issue concerns the naked-eye visibility of
the purple-blue upper atmosphere color.

No big problem Fridger. I hadn't looked at any of these addons in
some time and was just digging for them for the post below where I
was making an image similar to one of Cassini's. I guess I was more
specifically interested in the blue haze. After reading the posts I see
why it is not included in the distribution.

I guess the true problem would lie in the search for an addon that
contained that haze layer.

Sorry buggs,

apart from your "no big problem, Fridger", I am not sure whether I
managed to really understand what you meant to say in your reply

I guess, you realized that I did not inlude the blue upper atmosphere
haze, since even after communication with the Cyclops lead scientist, it
remained controversal whether the haze could be seen visually (i.e
without using UV filters). Still the basic display rule for official
Celestia stuff is that things must be visible with the naked eye.
In any case the dynamic range of computer monitors is generally that
small (compared to that of the human eye) that we should better skip
the haze anyway...

But is it just that you don't care about this visibility issue and prefer to
have the blue haze displayed for your personal use?

I was surprised about your original formulation saying"...on getting
Titan's atmospheric coloring closer to reality"? since you sure
know that most of the Cassini photos are shot with filters. So when
talking about "reality" one has to watch out of course about
statements like "true-color" or similar.

Sorry for being confused about the content of your post.

Bye Fridger

t00fri wrote:So when talking about "reality" one has to watch out of course about statements like "true-color" or similar.

I should have been more clear in my post. Yes, I wanted a blue haze for my own use in order to simulate the photo taken by Cassini. I had a poor choice of words, especially using "reality". Sorry.

buggs_moran wrote:

t00fri wrote:So when talking about "reality"
one has to watch out of course about statements like "true-color" or
similar.

I should have been more clear in my post. Yes, I wanted a
blue haze for my own use in order to simulate the photo taken by
Cassini. I had a poor choice of words, especially using "reality".
Sorry.

OK, buggs, that I can understand.

There is another tricky issue about Titan's atmosphere about which I
had long (and most interesting) "friendly fights" with Grant
(Hutchison). It's the question whether --under favorable conditions--
the sun can be seen (visually) from Titan's surface! While Grant never
believed it, I was rather in favor. We discussed all sorts of fancy
theoretical optics arguments like Mie scattering etc.

Then at last:

The Cyclops team only recently presented a photo in the /visual/ spectral range,
where it was claimed that one occasionally may spot /visually/ certain
marks of Titan's surface from a distance!


Then it should also be possible to locate the sun from the surface....

Cheers,
Fridger

Heh, on a clear day you can see forever... I once wondered the
same thing for seeing Saturn from the surface. I would imagine since we
can make out details on the surface at times, the weather might cooperate
for a hint of Saturn as well. Perhaps during the "winter" near the equator.

Kathleen Burton @ NASA wrote:Titan has long puzzled scientists because of several unexplained features
in its thick, hazy atmosphere, composed largely of solid organic materials.
Voyager images taken in 1980, for example, show that the haze is much
brighter at Titan's summer hemisphere than at its winter hemisphere.
Earth-based observations also show that this difference in brightness
changes with Titan's seasons. Each season on Titan lasts for four Earth
years. Titan's haze also is much thicker near the polar caps than anywhere
else. But perhaps most puzzling, a layer of the haze is detached from the
rest of Titan's atmosphere, appearing like a ghostly shell floating in space.

One image that confused my original search on the blue haze layer was
this supposedly natural color shot from the ESA. They make no mention of
a UV filter that is mentioned in other pages.


http://www.esa.int/esa-mmg/mmg.pl?b=b&type=I&mission=Cassini-Huygens&single=y&start=13

And to answer Runar's post, yes, that is what I meant.

buggs_moran wrote:Heh, on a clear day you can see forever... I once wondered the
same thing for seeing Saturn from the surface. I would imagine since we
can make out details on the surface at times, the weather might cooperate
for a hint of Saturn as well. Perhaps during the "winter" near the equator.

Kathleen Burton @ NASA wrote:Titan has long puzzled scientists because of several unexplained features
in its thick, hazy atmosphere, composed largely of solid organic materials.
Voyager images taken in 1980, for example, show that the haze is much
brighter at Titan's summer hemisphere than at its winter hemisphere.
Earth-based observations also show that this difference in brightness
changes with Titan's seasons. Each season on Titan lasts for four Earth
years. Titan's haze also is much thicker near the polar caps than anywhere
else. But perhaps most puzzling, a layer of the haze is detached from the
rest of Titan's atmosphere, appearing like a ghostly shell floating in space.

One image that confused my original search on the blue haze layer was
this supposedly natural color shot from the ESA. They make no mention of
a UV filter that is mentioned in other pages.


http://www.esa.int/esa-mmg/mmg.pl?b=b&type=I&mission=Cassini-Huygens&single=y&start=13

And to answer Runar's post, yes, that is what I meant.

Yes, Buggs,

that was the image that made me contact the Cyclops
lead scientist . Note this is not "true color" but
"natural color" which is roughly "true color + possible
enhancements".

Bye Fridger

Buggs, the blue haze is featured in the Postcards Add-On.
Going a little off-topic, did any of you see this wonderful Titan pic, taken by Cassini a couple of weeks ago? It shows a spectacular view of the atmosphere layer...

http://www.universetoday.com/wp-content/uploads/2006/06/titan.jpg
Context: http://www.universetoday.com/2006/06/30 ... und-titan/

- rthorvald