Celestia Forums

H is used in germany instead of B (english? international?)

steffens

steffens wrote:H is used in germany instead of B (english? international?)

steffens

Also in English Paganini's concerto No. 2 is often denoted by it's original key designation "H minor" (instead of B minor).

Paganini was Italian, after all...

Bye Fridger

I thought western music had long since been standardised to use the A to G scale... So "H minor" is really B minor? First I've ever heard of it...

To be honest I thought you meant G minor but missed the key on the keyboard and typed H instead...

Fridger:

In viewing Saturn in your screenshots above, it sure does not look like the default Saturn texture that is included with Celestia 1.3.2 or 1.4.0.

Is it different? If so, is the texture available on your website?

Frank

fsgregs wrote:Fridger:

In viewing Saturn in your screenshots above, it sure does not look like the default Saturn texture that is included with Celestia 1.3.2 or 1.4.0.

Is it different? If so, is the texture available on your website?

Frank

Frank,

yes you are right. Grant had taken care of the default Saturn texture and his taste was to take Steve Alber's texture which is much more pale and blue-grayish in the southern hemisphere. My attitude was somewhat different: My Saturn texture (above) models perfectly what is published officially by NASA as a socalled 'natural color' Saturn photo from Cassini!

I personally prefer the above colors, since I have looked at Saturn for many many hours in my life through my telescope. The resemblance with the above Saturn texture is much closer than what I get from Steve Alber's texture.

Bye Fridger

t00fri,

will you release your iapetus texture, with spec and bumps ?

Cham wrote:t00fri,

will you release your iapetus texture, with spec and bumps ?

Sure enough. It will also be part of the official forthcoming Celestia distribution. However, reduced to 1k, as usual.

Bye Fridger

Fridger:

PLEASE release your Saturn and spec textures and ssc atmosphere entries on your site.

PLEASE

Frank

fsgregs wrote:Fridger:

PLEASE release your Saturn and spec textures and ssc atmosphere entries on your site.

PLEASE

Frank

Frank,

as we know since a few days from Cassini, the northern Saturn hemisphere is much more blue than it was so far assumed. Since I tend to adhere to public texture releases that do NOT have to be changed a few days later I would rather prefer to send you my present Saturn stuff by PM.

Bye Fridger

Does anyonr know why Saturns northern hemisphere is bluer now,is it because it is "winter" in the north right now?Is this why Uranus and Neptune are blue-because of the cold?Jestr

jestr wrote:Does anyonr know why Saturns northern hemisphere is bluer now,is it because it is "winter" in the north right now?Is this why Uranus and Neptune are blue-because of the cold?Jestr

Isn't it pretty damn cold there in "summer", too??

Bye Fridger

I guess so but could the change in temperature affect the colour of the clouds in this way?This article suggests the colder temperature is related to the ring-shadows
http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=1350
maybe a combination of both winter and the shadows?Jestr

jestr wrote:I guess so but could the change in temperature affect the colour of the clouds in this way?This article suggests the colder temperature is related to the ring-shadows
http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=1350
maybe a combination of both winter and the shadows?Jestr

Yes, I guess I understand the argument they give on the NASA site. It's unrelated to summer/winter. Rather its the analogue mechanism that lets us see the sky in red towards the sun in the evening when the sun's light path through the atmosphere is getting very long: all blue rays are "scattered away from the sun" and hence we just see the left-over red. In case of Saturn, the sun-lit southern hemisphere invokes a much shorter light path than the shadowed north of Saturn. But us, the observers, do not look towards the sun this time . So we see the diffusely scattered blue light away from the sun's direction...

Bye Fridger

Is this the reason that the southern hemisphere was paler/greyish at the time of the Voyager encounters -I checked in Celestia and for Voyager1 encounter Saturns ring shadow seems to fall roughly along the equator in 1980,but is slightly inclined to the southern hemisphere by the time of the voyager2 encounter.Right now the southern hemisphere seems a lot more red/orange -is this just a trick of the light also (so to speak)?Jestr

Hi - from what I've heard, the thinking on the science team is that the colder temperatures in the northern hemisphere cause a reduction in clouds and haze (possibly with downward motion). In the clearer atmosphere all that is left is blue sky (like the Rayleigh scattering on earth). I wonder though if there is any coloration related to methane similar to what may occur on Neptune?

Fridger,

Near the bottom of page 2 you mention Grant working with a Saturn texture by me. Actually I have only done a Jupiter texture (taken from Cassini). Is Grant using mine from Jupiter, and/or using someone elses for Saturn?

scalbers wrote:Fridger,

Near the bottom of page 2 you mention Grant working with a Saturn texture by me. Actually I have only done a Jupiter texture (taken from Cassini). Is Grant using mine from Jupiter, and/or using someone elses for Saturn?

Sorry Steve,

I have indeed mixed it up:

The Saturn texture we have as default in Celestia is from
Bj?¶rn J??nsson,
http://www.mmedia.is/~bjj/

Greetings,
Bye Fridger

Hi all,

I am really sorry for simply forgetting to upload my finalized 2k Iapetus texture, that is finished already since February 16! OK, here it is, at last (5.76 MB):

*********************************************
http://www.shatters.net/~t00fri/iapetus.zip

*********************************************
A description of the raw textures used and some details of the making process are found in the Readme. A preview is here since February 13:

http://www.shatters.net/forum/viewtopic.php?t=6663&start=15

Just unzip the ZIP archive in your 'extras' folder. Then your default Iapetus texture will be appropriately modified. Please let me know if there are problems with Windows. For Linux I have tested everything.

Enjoy,

Bye Fridger

Based on my own experiments compositing Cassini raw images, I suspect that these pictures of Iapetus that show the dark Cassini Regio as chocolate-brown are not actually visible-light composites. I think they're IR/green/UV composites. If you use the pictures taken through the red-green-blue filters instead, and compose them assuming the relative brightnesses are accurate, the dark area just looks charcoal gray; there's not much visual difference from the grayscale frames. If that's so, then none of these brown textures is actually a realistic natural-color image.

However, JPL may know something about the relative exposure times, etc. of these frames that I don't. The captions on the released color pictures sometimes claim that the chocolate-brown Iapetus is "near natural color" and sometimes they don't.

Matt McIrvin wrote:Based on my own experiments compositing Cassini raw images, I suspect that these pictures of Iapetus that show the dark Cassini Regio as chocolate-brown are not actually visible-light composites. I think they're IR/green/UV composites. If you use the pictures taken through the red-green-blue filters instead, and compose them assuming the relative brightnesses are accurate, the dark area just looks charcoal gray; there's not much visual difference from the grayscale frames. If that's so, then none of these brown textures is actually a realistic natural-color image.

However, JPL may know something about the relative exposure times, etc. of these frames that I don't. The captions on the released color pictures sometimes claim that the chocolate-brown Iapetus is "near natural color" and sometimes they don't.

Matt,

as to your remarks, I have two points to make, one of principal (1) and one of practical (2) nature:

(1) I think it is important for Celestia for various reasons, to use /officially/ published numerical and imaging data throughout. Even though, what NASA likes to call 'natural color' or 'almost true color' might not be entirely natural or 'true'. It is an important and proven strategy in natural science (as you surely know well) to preserve /transparency/ of (data) sources as much as possible, along with transparency of /citations/ of these sources! For that reason, I strongly adhere to their published 'natural color' imaging, although privately, I might well bet that my own "homebrewn" RGB composite is superior...


2) Since the RGB RAW images are really NOT calbrated, you may easily generate almost arbitrary composite colors. I also played with them . On the other hand if one replaces a blue filter by a near UV centered one and a red filter by a near IR centered one, and if the transmission spectrum of these filters is very well known, you will certainly be able to generate reasonable colors in the end. It's all a matter of calibration and careful corrections, given well-known characteristics.

Bye Fridger