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PostPosted: Tue, 15-09-09, 20:03 GMT 
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Hi all,

after my original thread on Phobos in color, about 1.5 years ago,
http://forum.celestialmatters.org/viewtopic.php?t=225

a "Phobos revival" took place during last week, mainly in intensive dialog between Steve (aka cartrite) and John Van Vliet both here and over at shatters.net:

http://forum.celestialmatters.org/viewtopic.php?t=323
http://www.shatters.net/forum/viewtopic.php?f=6&t=14240

So I thought, some more diversity would be good. Hence, let me present in this thread my 4k colored Phobos that I did a short while ago for my ongoing Celestia.Sci project. That's also why this thread will be a preview with download lacking for now...

Note: Celestia.Sci is ONLY a pseudonym for an ongoing Celestia-related effort of mine that has not been defined in public so far ;-) .

Since I am not a modeller kind of person, I took the official Phobos model as a basis, that is also part of the Celestia distribution. Here are some resources for the underlying model that matches with the scientific input textures I used:
Latest version of
EAR-A-5-DDR-SHAPE-MODELS-V2.1 , http://www.psi.edu/pds/resource/oshape.html
by Peter Thomas/Cornell

Much more work went into the surface texture, however! There are plenty of new imaging data, but various published textures need be merged and require lots of texture work. Notably, the North pole region was pretty tedius, since it is highly prone of massive distortions in case of slight inaccuracies. Also the familiar polar pinch problem required work. The result is not perfect, but altogether quite OK.

The present Phobos texture in the official Celestia distribution is only 1k, and moreover it is airbrushed, rather than based on photographic imaging!

The two 5760x2880 input textures that I mainly used are :
  • http://www.psi.edu/pds/asteroid/EAR_A_5_DDR_SHAPE_MODELS_V2_1/data/m1phobosm.fit (a fits format file from the above archive, matching the model)
  • http://www.esa.int/esaCP/SEMXE6RTKMF_Austria_1.html
    This mosaic image is composed by 53 pictures obtained by the Super Resolution Channel (or SRC, a part of the High Resolution Stereo Camera experiment) on board ESA’s Mars Express.
    Credits: ESA/ DLR (S. Semm, M. Wählisch, K.Willner)/ FU Berlin (G. Neukum)

There is some little left-over also from the old 1k texture.

A fair amount of care went into the coloration by computer (GIMP) as usual. Here is the template I used which is part of the excellent HiRISE IRB color imaging of the MRO mission,

http://hirise.lpl.arizona.edu/phobos.php

Image

The color images of Phobos were made by combining data from HiRISE’s blue/green, red, and near-infrared channels. The color data accentuate details not apparent in the black and white images. For example, materials near the rim of the huge Stickney crater appear bluer than the rest of Phobos. Based on analogy with materials on our own moon, this could mean this surface is fresher, and therefore younger, than other parts of Phobos.

So it's NOT truecolor, but should be not too far away, apart from specially enhanced details,

Altogether the coloration as well as the texture quality turned out pretty well, I think. Here is a first Phobos image, where you can see the many delicate shades of color ranging from a bright orange, to dark brown just like the corresponding template:

Image

Of course, I performed the coloration in several runs, each time selecting particular areas both in the template and in the source gray texture. This way I get pretty close to the original colors.

Next, some representative views exposing different aspects of Phobos' complex 3d shape:

Image

You can clearly see the high amount of detail due to the 4k texture of good quality!
Here is a related close-up showing the amazing groves:

Image

Or here with the amazing Stickney crater and the conspicuous white ice cover

Image

Image

Next let us carefully inspect how precisely the locations of the deep craters match the corresponding labels in the centers! This is indeed very nice I think. Moreover, I marked in pink the positions of the North(N) and South poles(S). So you can see that the polar pinch problem is not too bad! Also note the lack of distortions of the crater shapes close to the North pole. That was pretty much fine tuning work...

North pole side
===============
Image

South pole side
================
Image


So that's it for now, here are a few final shots for "dreaming"

Image

Image

Image


Let me know...

Enjoy,
Fridger


Last edited by t00fri on Thu, 17-09-09, 16:11 GMT, edited 3 times in total.

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PostPosted: Tue, 15-09-09, 21:00 GMT 
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You're "dreaming" shots are definitively cool...

Would be nice to see how this fresh (not so, ok) texture goes with John's new model...


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PostPosted: Tue, 15-09-09, 21:03 GMT 
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ElChristou wrote:
You're "dreaming" shots are definitively cool...

Would be nice to see how this fresh (not so, ok) texture goes with John's new model...


What do you mean with "this fresh (not so, ok) texture"??

I think this new texture I made not long ago is the best available by far...
From the fact that all crater labels are spot-on centered in their craters, you can see already how accurate it is. Not at all trivial with this potato shape!.

Fridger


Last edited by t00fri on Thu, 17-09-09, 18:34 GMT, edited 1 time in total.

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PostPosted: Tue, 15-09-09, 21:45 GMT 
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t00fri wrote:
I think this new texture I made not long ago is the best available by far...
You see already how accurate it is since all crater labels are spot-on centered in their craters. Not at all trivial with this potato shape!.

Fridger


Well, you definitely got my attention there Good Doctor... :wink:

Wow... :shock:

Thanks, Brain-Dead


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PostPosted: Tue, 15-09-09, 21:51 GMT 
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t00fri wrote:
...What do you mean with "this fresh (not so, ok) texture"??


My bad, the thread about new phobos imaging was 1.5 years ago, not the texture itself... :oops:


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PostPosted: Tue, 15-09-09, 22:55 GMT 
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ElChristou wrote:
t00fri wrote:
...What do you mean with "this fresh (not so, ok) texture"??


My bad, the thread about new phobos imaging was 1.5 years ago, not the texture itself... :oops:


Correct. ;-)

Since these days my new textures (and plenty of new code) go into the Celestia.Sci "pool", my work on new textures will typically not appear anywhere until their eventual public release. I pulled my new Phobos texture "out of the pocket", because I followed with much interest Steve's and John's ongoing dialog about Phobos throughout the past week.

Due to the irregular shape of Phobos and the harder situation with available scientific mosaic maps, I have spent much more time on that Phobos texture (about 2-3 weeks ago) than on numerous other maps that I have made before.

In my original Phobos thread 1.5 years ago, I presented the first colored Phobos texture using my GIMP-coloration technique based on MRO/HiRISE color imaging. However, that was all based on the 1k, airbrushed map which is still part of the 1.6.0 Celestia distribution.

Fridger


Last edited by t00fri on Thu, 17-09-09, 18:37 GMT, edited 3 times in total.

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 Post subject: re
PostPosted: Wed, 16-09-09, 3:21 GMT 
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Nice

if you want why don't we use your map and my cmod in the official release
the cmod WILL need to be smaller . It is a 11.9 meg ASCII right now
-- that is if EVERYONE wants to do that --
they should match up nicely seeing as i used my old ( new color) map

i am, tonight about to remap the few mro images to the new shapemodel ( that the cmod is made from)for isis
then the fun begins .Incorporating it into the current map
Quote:
. Not at all trivial with this potato shape!.

how true and WHAT an ODD potato shape it has too.

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 Post subject: Re: re
PostPosted: Wed, 16-09-09, 9:08 GMT 
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John Van Vliet wrote:
Nice

if you want why don't we use your map and my cmod in the official release
the cmod WILL need to be smaller . It is a 11.9 meg ASCII right now
-- that is if EVERYONE wants to do that --
they should match up nicely seeing as i used my old ( new color) map

i am, tonight about to remap the few mro images to the new shapemodel ( that the cmod is made from)for isis
then the fun begins .Incorporating it into the current map
Quote:
. Not at all trivial with this potato shape!.

how true and WHAT an ODD potato shape it has too.


Thanks!

Because of an issue of principle between ChrisL and myself, I have stopped to contribute my textures to the official Celestia distribution. It was his choice. My textures will be part of my forthcoming Celestia.Sci distribution. Whenever it will be released...


Fridger


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 Post subject: Re: re
PostPosted: Wed, 16-09-09, 12:01 GMT 
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t00fri wrote:
Because of an issue of principle between ChrisL and myself, I have stopped to contribute my textures to the official Celestia distribution. It was his choice. My textures will be part of my forthcoming Celestia.Sci distribution. Whenever it will be released...


Fridger


Aw, so sad... :cry:
This is our loss, not Chris L's.

Very much looking forward to the Celestia.Sci distribution.

If I can contribute anything to your release, please don't hesitate to ask.
I know I'm not very talented, but my heart (and will) is dedicated to this kind
of quality.

Many thanks, Brain-Dead


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PostPosted: Thu, 17-09-09, 15:42 GMT 
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I've done a bit of cleaning; the removed posts can be found in The CM Museum of inappropriate posts.

Fridger, congratulation for this texture!


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PostPosted: Thu, 17-09-09, 16:44 GMT 
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Friends,

after Mona cleared up most of the previous mess (Thanks Mona: "Tu es charmante"!!), let's return to "business as usual".

In this post I want to draw peoples' attention to a most interesting ESA-collaboration branch site in Berlin/Germany:

Freie Universitaet Berlin: http://www.geoinf.fu-berlin.de/eng/proj ... vation.php

At this University@Berlin much of the recent hires imaging analysis about Phobos is done:

Prof. Dr. Gerhard Neukum
Principal Investigator HRSC Experiment

Freie Universitaet Berlin
Fachbereich Geowissenschaften


A number of crucial news may be found here:

An animation of a new Phobos shape model (spherical harmonic function of degree and order 17) based on control point network derived from 53 SRC and 16 Viking images is shown! Matching to this latest model, there is the Phobos Super Resolution Channel (SRC) texture data

(Note: SRC is a part of the HRSC experiment).

As I experienced painfully, a transition from imaging input matched to Peter Thomas' shape model to this new, more sophisticated model is all but trivial! So for the model constructors among us, watch out, it's a bit tricky ;-)

Somehow the most pleasing and valuable part of that site are the many beautiful hires photos of Phobos that served as a basis for all these new, exciting results! Let me just copy a few here for getting some people motivated to learn more about this amazing Moon:

Here is --first of all-- a great image displaying the Phobos lat-long coordinates, as well as the recently re-approved crater labels. Note their perfect center locations!! I actually checked these coordinates and made sure that Celestia 1.6.0 has the latest set!

Image


Here are two great views of the northern portion seen from the "side" and from the "back":

Image

Image

Next some beautiful zoom-in photos, corresponding to the three squares in the previous overview image:

SRC 3:
---------
Image
SRC 4:
---------
Image

SRC 5:
----------
Image

and finally a real close up of the North pole region:

Image

So this is a dorado for "reprojection fans" like myself! There are many more of these detail shots on the above site. These were just meant as appetizers...


Enjoy,
Fridger


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PostPosted: Thu, 17-09-09, 17:44 GMT 
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I'm wondering about such line of impacts:
Image

Could it be an evidence of some ring systems around Mars? (Apart Phobos crusing a ring I cannot imagine how such line could be done... :? )


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PostPosted: Thu, 17-09-09, 17:54 GMT 
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There are plenty of theories about the origin of Phobos and notably the origin of those striking parallel grooves.

First of all, Phobos' density has been measured to be too low for being solid rock, hence may be there is some hidden ice reservoir somewhere? Some say Phobos is even hollow inside ;-) .Another mystery is how such a huge crater impact as Stickney could have happened without dismantling Phobos entirely?

In the light of these pecularities, the striking parallel groove pattern all over Phobos is a matter of continued intense discussion.

Like here

http://www.lpi.usra.edu/meetings/lpsc2006/pdf/2195.pdf

or here
http://adsabs.harvard.edu/abs/1994P&SS...42..519M

or here (Nature)
http://www.nature.com/nature/journal/v2 ... 282a0.html

Unfortunately, in case of the latter two, you may only read the abstracts without paying money...

Fridger


Last edited by t00fri on Thu, 17-09-09, 18:44 GMT, edited 1 time in total.

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PostPosted: Thu, 17-09-09, 18:42 GMT 
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(mmhm... your 2 first link are the same...)


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PostPosted: Thu, 17-09-09, 18:45 GMT 
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Sorry, thanks for watching out! Ich changed the link appropriately.

F.

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