It is currently Tue, 25-07-17, 16:38 GMT

All times are UTC




Post new topic Reply to topic  [ 21 posts ]  Go to page 1, 2  Next
Author Message
PostPosted: Fri, 02-10-15, 8:26 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4467
Location: Hamburg, Germany
Well, after a new high resolution cylindrical map of Pluto has become available by Sep. 24, 2015, I thought I might devote some more serious efforts to creating a corresponding texture for celestia.Sci and Celestia.

Here is a short listing of the essential steps and the used data references:

  • As the basic grayscale cylindrical map I took PIA19858 dated July 27, 2015, with a size of 18630 x 9315. (http://photojournal.jpl.nasa.gov/catalog/PIA19858)

  • The new, officially released NASA/NewHorizons data of Sep. 24 concern a cylindrical projection map of Pluto, in enhanced, extended color, being the most detailed color map of Pluto ever made. http://www.jpl.nasa.gov/spaceimages/det ... d=PIA19956. Yet the corresponding official resolution is "only" 5999x3000 pix.

    However, another texture file named pmap_pmc195_8092-shenk.jpg with the same content, but much higher resolution (11465x5733) is available from various web sources. The map covers less terrain than the above base texture PIA19858.

  • For celestia.Sci or Celestia we want Natural Color rendering rather than Enhanced Extended Color, despite the cognitive merits of the latter. Hence, the next step was to first convert the extended color rendering also to grayscale via the GIMP and then to superimpose the two gray maps as layers. Note that a non-negligible re-alignment of the two cylindrical maps was required!

  • The most tedious step was to fit the new hires texture seemlessly into the base texture PIA19858 and to eliminate all visible (nasty) transitions among the many involved imaging patches in the official versions. All transitions are now smooth...

  • Finally I used the global photo of Pluto in Natural Color,
    http://www.nasa.gov/sites/default/files ... -color.jpg, as a color reference in the automatic GIMP colorization module.

  • After some remaining small touch-ups, I'll release the resulting 16k texture for download.

For now, here are a several representative shots with my resulting Pluto texture in celestia.Sci

[By all means, click on image and hit browser full screen (F11 key in Firefox)]
Attachment:
pluto1.jpg
pluto1.jpg [ 133.92 KiB | Viewed 2761 times ]


Attachment:
pluto2.jpg
pluto2.jpg [ 309.86 KiB | Viewed 2761 times ]


Attachment:
pluto3.jpg
pluto3.jpg [ 189.46 KiB | Viewed 2761 times ]


Attachment:
pluto5.jpg
pluto5.jpg [ 108.38 KiB | Viewed 2761 times ]


Attachment:
pluto6.jpg
pluto6.jpg [ 203.56 KiB | Viewed 2761 times ]


Enjoy,

Fridger

PS: Note that yesterday, Oct. 1st, a new stunning hires, enhanced color photo of Charon was released by NASA/NewHorizons:

[By all means, click on image and hit browser full screen (F11 key in Firefox)]
Attachment:
Charon-Neutral-Bright-Release.jpg
Charon-Neutral-Bright-Release.jpg [ 1.19 MiB | Viewed 2751 times ]


http://pluto.jhuapl.edu/Multimedia/Scie ... age_id=323

So there is more work ahead... ;-)

_________________
Image


Top
 Profile  
 
PostPosted: Sat, 03-10-15, 18:23 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4467
Location: Hamburg, Germany
Don't overlook my previous post

Here is a qualitative comparison of a zoomed view in celestia.Sci that roughly matches a great grayscale NewHorizon(NH) Photo released Sep. 17 2015 (http://pluto.jhuapl.edu/Multimedia/Scie ... age_id=308).

NH photo from 18000 km distance, shot on July 14 2015:

[By all means, click on image for an adequate display size!]
Attachment:
plains_mountains_hazes_NH_photo_mono.jpg
plains_mountains_hazes_NH_photo_mono.jpg [ 142.65 KiB | Viewed 2725 times ]


and now the same view with celestia.Sci:
(Note: no Normalmap yet, hence mountains look too flat (squeezed)!).

[By all means, click on image for an adequate display size!]
Attachment:
plains_mountains_hazes_Sci3.png
plains_mountains_hazes_Sci3.png [ 606.1 KiB | Viewed 2725 times ]


Note:
  • This configuration is very sensitive to the used orbital and other parameters, since the backlit haze is only visible shortly before sunset!
  • At this point the orbital elements and other parameters of Pluto have not yet been updated. Hence shifts in time are to be expected.
Will get to this ASAP.

Fridger

_________________
Image


Top
 Profile  
 
PostPosted: Tue, 06-10-15, 20:12 GMT 
Offline
User avatar

Joined: Mon, 07-01-08, 13:30 GMT
Posts: 339
Location: Switzerland
Great results here! Out of interest is there any colour information for the backlit haze, I've only seen the grayscale images.


Top
 Profile  
 
PostPosted: Wed, 07-10-15, 6:48 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4467
Location: Hamburg, Germany
ajtribick wrote:
Great results here! Out of interest is there any colour information for the backlit haze, I've only seen the grayscale images.


Hi Andrew,

since quite a while I am scanning the net carefully for color info about the backlit configuration of Pluto. There is one further colored image (Wikipedia), the color of which seems theory-based as well.

Image

I was unable to find any substance about this image anywhere. Anyway, an understanding of the Nitrogen issue in the atmosphere seems a crucial point...

No direct color measurements published as far as I can tell...unfortunately!

In my case,
Attachment:
pluto_backlit_small.jpg
pluto_backlit_small.jpg [ 19.13 KiB | Viewed 2680 times ]


the Mie theory settings are assumed to be somewhat similar to Titan (hydrocarbons!)...

For the view in my post above this one (download/file.php?id=928&mode=view), I have meanwhile implemented more accurate solarsys.ssc settings, which -- for the last image in my previous post -- imply a haze color quite similar to the overall surface color. This effect I had already suspected above.

Fridger

_________________
Image


Top
 Profile  
 
PostPosted: Wed, 07-10-15, 17:10 GMT 
Offline
User avatar

Joined: Fri, 03-04-09, 8:21 GMT
Posts: 211
t00fri wrote:
NH photo from 18000 km distance, shot on July 14 2015:

(http://pluto.jhuapl.edu/Multimedia/Scie ... age_id=308)

Fridger

Nice .. and with a bit of scaling, it makes for a nice Desktop Background:


Attachments:
Pluto-Wide-DESKTOP-CC.jpg
Pluto-Wide-DESKTOP-CC.jpg [ 460.33 KiB | Viewed 2670 times ]

_________________
CITIZENS OF CM - JOIN THE REVOLUTION
...black out your avatar
THE AVATARS ARE REVOLTING !!!
Top
 Profile  
 
PostPosted: Wed, 07-10-15, 20:53 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4467
Location: Hamburg, Germany
Yes, CC,

I like that photo also very much...

Fridger

_________________
Image


Top
 Profile  
 
PostPosted: Thu, 08-10-15, 3:42 GMT 
Offline
User avatar

Joined: Tue, 04-09-07, 21:55 GMT
Posts: 757
Location: N 42.38846 W 83.45456
i am using the colored ( by ngunn i think ) one
Image
and the B&W close up
Image

_________________
"I don't pitch Linux to my friends, I let Microsoft do that for me."
Using OpenSUSE 42.1 & Scientific Linux 6.7


Top
 Profile  
 
PostPosted: Thu, 08-10-15, 9:48 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4467
Location: Hamburg, Germany
John,

the colored Pluto photo looks certainly appealing. But what color scheme was used?
If any, it is presumably enhanced, extended color and certainly not true color. Of course, it's fine as a wallpaper.

[To enlarge the image, click on it, please]
Attachment:
pluto_zoom.jpg
pluto_zoom.jpg [ 63.76 KiB | Viewed 2642 times ]


Notably, the haze has a light blue color, which would be important to know for sure...

I'd appreciate if you can find the link for that image. Presumably it's from deep down in the posting tree of UMSF ;-) ?

Fridger

_________________
Image


Top
 Profile  
 
PostPosted: Thu, 08-10-15, 16:41 GMT 
Offline
User avatar

Joined: Tue, 04-09-07, 21:55 GMT
Posts: 757
Location: N 42.38846 W 83.45456
this is the one i used
http://www.unmannedspaceflight.com/inde ... t&p=226435

a correction
Ian R and not Ngunn made it

_________________
"I don't pitch Linux to my friends, I let Microsoft do that for me."
Using OpenSUSE 42.1 & Scientific Linux 6.7


Top
 Profile  
 
PostPosted: Thu, 08-10-15, 17:11 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4467
Location: Hamburg, Germany
John Van Vliet wrote:
this is the one i used
http://www.unmannedspaceflight.com/inde ... t&p=226435

a correction
Ian R and not Ngunn made it


Many thanks John! I searched for Ngunn in UMSF and thus could hardly succeed ;-) . Unfortunately, there is no further specification about the used color, just a loose reference to the MVIC camera, the color imaging features of which were not used though.

I read in a NH article that the image in question, download/file.php?id=927&mode=view, is presently available only as a one channel (grayscale) photo, simply for reasons of saving time in the image transfer from Pluto. After all, color images take 3 times as long as mono images.

Fridger

_________________
Image


Top
 Profile  
 
PostPosted: Thu, 08-10-15, 17:39 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4467
Location: Hamburg, Germany
Incidentally, here is a "2 sec proof" that the above coloration corresponds rather closely to enhanced, extended color

I used the latest image of Pluto, http://pluto.jhuapl.edu/Multimedia/Scie ... /Shenk.jpg, in enhanced, extended color as a color reference in TheGimp coloration module, as applied to download/file.php?id=927&mode=view.

Here is my result obtained after a few seconds of CPU time:
[To enlarge the image, click on it, please]
Attachment:
plains_mountains_hazes_extended_enhanced_color.jpg
plains_mountains_hazes_extended_enhanced_color.jpg [ 247.16 KiB | Viewed 2630 times ]

The similarity to the one above, colored by Ian R is apparently quite close
[To enlarge the image, click on it, please]
Attachment:
pluto_zoom.jpg
pluto_zoom.jpg [ 63.76 KiB | Viewed 2630 times ]


Actually, I like my color version better, since the haze is gray rather than bright blue (??) ...

Fridger

_________________
Image


Top
 Profile  
 
PostPosted: Thu, 08-10-15, 20:49 GMT 
Offline
User avatar

Joined: Mon, 07-01-08, 13:30 GMT
Posts: 339
Location: Switzerland
And right on time, according to this article on SpaceRef, the haze is blue:

Blue Skies and Water Ice on Pluto


Top
 Profile  
 
PostPosted: Fri, 09-10-15, 7:23 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4467
Location: Hamburg, Germany
ajtribick wrote:
And right on time, according to this article on SpaceRef, the haze is blue:

Blue Skies and Water Ice on Pluto


Indeed ;-) ...and very surprisingly! In your quote Alan Stern, the NewHorizons principal investigator states e.g.

"Who would have expected a blue sky in the Kuiper Belt? It's gorgeous...

And furthermore:
"The haze particles themselves are likely gray or red, ...

The official NH and NASA releases are here
http://pluto.jhuapl.edu/Multimedia/Scie ... age_id=327
http://www.nasa.gov/nh/nh-finds-blue-sk ... e-on-pluto
Attachment:
Blue-Skies-on-Pluto-FINAL.jpg
Blue-Skies-on-Pluto-FINAL.jpg [ 26.31 KiB | Viewed 2613 times ]

So the blue backlit appearance requires to tune some relevant parameters in the Mie theory that governs the way the scattering takes place ...

The new evidence for water ice is of course also spectacular...

Fridger

_________________
Image


Top
 Profile  
 
PostPosted: Mon, 12-10-15, 18:43 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4467
Location: Hamburg, Germany
Reproducing the blue halo of backlit Pluto turned out to be a challenge that was less easy than I thought at first.

Before getting to my results, let me recall the meaning of the various Mie theory parameters that need to be tuned:

Quoted from ChrisL from quite some time ago:

Mie
A float value giving the fraction of light scattered per kilometer at the planet's surface ('sea level')

MieAsymmetry
Henyey-Greenstein phase function parameter for wavelength independent scattering. A floating point value between -1 and 1, with -1 indicating complete backscattering, 1 complete forward scattering, and 0 isotropy.

MieScaleHeight
Scale height for wavelength independent scattering particles. Height in kilometers at which wavelength independent scattering is 1/e of the value at the surface

Rayleigh
Wavelength dependent scattering coefficients. Three values giving fraction of red, green, and blue light scattered per kilometer at the planet's surface. To simulate Rayleigh scattering, they should be in ratios that fit the 1/wavelength^4 behavior, though this is not required.

RayleighScaleHeight
Scale height for wavelength dependent scattering. Currently ignored; MieScaleHeight is used for both Rayleigh and Mie scattering.

Absorption
Three values giving the fraction of red, green, and blue light absorbed per kilometer at the planet's surface.

-----------------------------------------------------

Let me add some further qualitative remarks about the essential effects these parameters have:

  • A larger (negative) MieAsymmetry than on Earth (e.g. -0.5.. -0.55)
    is responsible for the conspicuous "ring of light"
    when the atmosphere is backlit (cf TITAN!)
  • the Rayleigh RGB values indicate the color components that are to be prominent in the highest part of the illuminated atmosphere
  • the Absorption RGB values specify the amount of absorption as visible in the backlit color composition of the "ring of light". R=0.0 means red remains (i.e undergoes ZERO absorption)! Etc.

As you see there a quite a few free parameters to fix which is all but straightforward.

My (non-final) result is

Code:
Modify "Pluto:134340 Pluto" "Sol"
{
     Atmosphere {
         Height      130.0 # official value [km]
         Lower       [0.232 0.1929 0.1566]
         Upper       [0.07725 0.0643 0.0522]
         Sky         [ 0.3 0 0 ]
       
         Mie              0.00012
         MieAsymmetry    -0.50         
         Rayleigh [0.000005 0.000054 0.000269542]
         Absorption [0.000367 0.000245 0.0]         
         MieScaleHeight 49.0
         }   
}


Here is the corresponding backlit view of Pluto. It's not final but shows that I am on the right track ;-)

[To enlarge the image, click on it, and hit browser full screen (F11 key in Firefox)]
Attachment:
blue_halo_.Sci_big.jpg
blue_halo_.Sci_big.jpg [ 113.58 KiB | Viewed 2510 times ]


Implying blue skies on Pluto!
[To enlarge the image, click on it, please]
Attachment:
blue_halo_.Sci_zoom.jpg
blue_halo_.Sci_zoom.jpg [ 94.21 KiB | Viewed 2513 times ]


and blue sunsets/sunrises
[To enlarge the image, click on it, and hit browser full screen (F11 key in Firefox)]]
Attachment:
Blue_sunset_sunrise.jpg
Blue_sunset_sunrise.jpg [ 67.69 KiB | Viewed 2510 times ]


Fridger

_________________
Image


Top
 Profile  
 
PostPosted: Sun, 15-11-15, 2:08 GMT 
Offline
User avatar

Joined: Tue, 04-09-07, 2:32 GMT
Posts: 430
Location: South Korea
The backlit atmosphere looks great, but the atmosphere is too visible from the front in the .Sci rendering.
There is no halo visible from the front in NH images. I guess the backlit halo is only visible in NH images because of the likely image enhancement, and/or sensor dynamic range.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 21 posts ]  Go to page 1, 2  Next

All times are UTC


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group