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PostPosted: Tue, 30-11-10, 22:27 GMT 
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Maybe this will be of interest: Paul Schenk has put up a blog post about mapping the topography of Mimas, Enceladus, Tethys, Dione, Rhea and Iapetus. Unfortunately I don't think these will be usable for Celestia at present, but worth a read.


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PostPosted: Wed, 01-12-10, 19:28 GMT 
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ajtribick wrote:
Maybe this will be of interest: Paul Schenk has put up a blog post about mapping the topography of Mimas, Enceladus, Tethys, Dione, Rhea and Iapetus. Unfortunately I don't think these will be usable for Celestia at present, but worth a read.


I knew that page by Dr. Paul Schenk. Thanks, Andrew, for linking it here!

I was always a bit sceptical about the comparatively strong coloration of his textures. The corresponding colors of the same moons from the Ciclops team are soooo much weaker, while usually, colorations from the big space agencies tend to be exaggerated (for PR purposes... ;-) ).

So I got to understand what led him to these vivid colors and how solid his arguments are.

His topographic maps of the icy Saturnian moons are indeed most interesting, notably since they constitute the first TRUE topographic measurements (via the Cassini stereo camera) for the Saturnian moons

Of course, I could not resist to try and exploit this new information for Celestia, at least partially. The Iapetus map on Schenk's web page has a sufficiently big size. So I downloaded it, rotated the central meridian and then did some significant offset adjustments using GIMP. As a reference I used my 4k Iapetus texture that I did for the official Celestia distribution some time ago.

So here is a small "photo shooting" illustrating what amount of visual improvements one could expect from such topographic info. Unfortunately, there are still quite a few "empty spaces" all over Schenk's topographic texture... Starting from his original topographic map, I converted it into a Isis3 CUB file by means of (std2isis). Next I converted the .cub file into a signed 16bit binary file (isis2raw) that served as input for my nms normalmap tool. The following screenshots are based on this resulting 4k normalmap. You may download it at the bottom of my post.

Image

Image

Here is a neat 3d display of the famous equatorial ridge!
Image

And here in a close-up view
Image

Same on the snowy side, but with some "holes" (at the bottom)
Image


Download 4k normalmap I have derived from Schenk's topographic imaging data:
++++++++++++++++++++++++++++++++++
http://www.celestialmatters.org/users/t ... s4k-nm.png
++++++++++++++++++++++++++++++++++
Note that I did NOT (yet) apply any cosmetic modifications to Schenk's original images and the resulting normalmap!

References:
Schenk, P. (2010) Global Topographic Mapping Of Saturn's Midsize Icy Satellites: System-wide Thermal And Impact Effects, Amer. Astron. Soc., D.P.S. meeting 42, abstr. 9.16.

Schenk, P. (2010) New Moons – First Global Topographic Maps of (Saturn's) Icy Moons,
http://stereomoons.blogspot.com/2010/11/new-moons.html

Enjoy,
Fridger


Last edited by t00fri on Fri, 03-12-10, 11:27 GMT, edited 2 times in total.

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PostPosted: Thu, 02-12-10, 19:43 GMT 
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Hi all,

those of you who have downloaded my "raw" iapetus4k normalmap (in my previous post), will have noticed that the "data-less" regions stick out in a nasty fashion, destroying much of the potentially nice visual appearance.

Therefore, I took some time today, applying quite a bit of "cosmetic improvement" WITHOUT modifying any of Dr. Schenk's topographical imaging data! While the applied manipulations (GIMP) might be an instructive teaching example for interested people, a tutorial also takes time to write...Since I am unsure about whether there are interested people at all, I skipped any educational efforts for now.

I think the results obtained were well worth my efforts...

Let me compare the "raw" and the "cosmetically improved" normalmaps.
For a better 3d impression, I have color-inverted the normalmap-displays. So don't be surprised about the yellow base color (instead of the familiar nm-blue!)

First look at my "raw" version of yesterday

Click for big images. Please do so, it's important!

Raw NM
Image

You see a number of bad artefacts notably the "empty regions" that will stick out like high-altitude plateaus in the actual 3d display by Celestia.

Next my improvements of today

Cosmetically improved NM
Image

In the actual 3d display by Celestia you will barely notice the areas without topographic data now. To show you the vastly improved appearance, I made a video. It's in Theora avi format and it's natural width is 1512 pix! Both under Linux and under Windows the well-known vlc player can nicely play this format. You may simply increase the vlc window with the mouse to get the best resolution!

I would advise to download the video before you play it. Since the resolution is rather high, you might well have problems trying to play it online.

Here is the video (75 MB)
+++++++++++++++++++++++++++++++++++++++++++++++++++
http://www.celestialmatters.org/users/t ... tus_nm.avi
+++++++++++++++++++++++++++++++++++++++++++++++++++

and here is my "cosmetically improved" 4k normalmap for download

+++++++++++++++++++++++++++++++++++++++++++++++++++
http://www.celestialmatters.org/users/t ... nm-new.png
+++++++++++++++++++++++++++++++++++++++++++++++++++
Enjoy,
Fridger

PS: Let me know if you have problems with the playing the video!


Last edited by t00fri on Sun, 05-12-10, 10:48 GMT, edited 1 time in total.

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PostPosted: Thu, 02-12-10, 21:48 GMT 
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Very nice video there, did you boost the specularity to bring out the details better? The normal map certainly makes a great addition to Iapetus: it has the advantage of having very different terrain types across the moon.


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PostPosted: Thu, 02-12-10, 22:41 GMT 
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ajtribick wrote:
Very nice video there, did you boost the specularity to bring out the details better? The normal map certainly makes a great addition to Iapetus: it has the advantage of having very different terrain types across the moon.


Indeed, I did a little magic with specular light in solarsys.ssc, precisely for the reason you mentioned. In a more finalized setting, I usually prepare a specular graymask to allow a certain amount of "specular shine" ONLY for icy regions. No time yet to do this.

I agree with you, the normal map emphasizes the different terrain types quite impressively.

Fridger


Last edited by t00fri on Thu, 02-12-10, 23:54 GMT, edited 1 time in total.

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PostPosted: Thu, 02-12-10, 23:39 GMT 
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Super cool...
G


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PostPosted: Fri, 03-12-10, 11:38 GMT 
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Dr. Schenk also prepared some great 3D videos involving the new topographic data about Saturn's medium sized moons. Here are the links

Saturnian Moons

1) The equatoria ridge of Iapetus

http://www.youtube.com/watch?v=o6J69uqPVGY

http://www.youtube.com/watch?v=GHRfbsap_rg

2) Inktomi - Rayed Crater of Rhea

http://www.youtube.com/watch?v=rMy9Cw8NkA4

3) Tethys and Odysseus

http://www.youtube.com/watch?v=9MsVGqgpjSc

4) Dione

http://www.youtube.com/watch?v=754G9nU5FDw

5) Rhea's Blue Streaks - Rings and Other Things!

http://www.youtube.com/watch?v=NDHZCOaTb-Y

6) Edge of Tirawa (Rhea)

http://www.youtube.com/watch?v=a6NedzqlFmQ

7) Mimas Rotating

http://www.youtube.com/watch?v=CwWBZFIBkr0


Don't miss these two hires from the Jupiter system!

Jupiter Moons

1) Tohil Mons, Io (High Resolution)

http://www.youtube.com/watch?v=q3Yji2ckO0g

2) Liftoff from Hi'iaka Montes

http://www.youtube.com/watch?v=Q2moWmpKRNg

Enjoy,
Fridger


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