Iapetus cmod

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John Van Vliet
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Iapetus cmod

Post #1by John Van Vliet » 28.09.2017, 16:05

a cmod from Dr. Paul Schenk's heightmap

http://stereomoons.blogspot.com/search?q=iapetus

a mesh and normal only preview
Screenshot_20170928_113631.png


THE ZIP File
https://drive.google.com/file/d/0B6ZYAd08tZL-Z1FybGFIMjdIbnc/view?usp=sharing

-- warning
this heightmap DOSE NOT align well with the texture ( cassini & cassini+voyager )

a 2k copy of the heightmap ( 8 bit copy of the 32 bit float data )
2k.IapetusHeight.png
Last edited by John Van Vliet on 29.09.2017, 02:44, edited 2 times in total.

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Post #2by Art Blos » 28.09.2017, 16:19

Wow! And where can I download this model? Or is it inaccessible?
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Post #3by FarGetaNik » 28.09.2017, 18:03

Fantastic! Thanks for sharing John! Was there some cleanup involved or did I miss the release of some more complete height map? It's definately better than anything I could do. But I managed to align the different patches pretty good with the latest color map by JPL...

This was my try btw, matching this texture: https://photojournal.jpl.nasa.gov/catalog/PIA18436
Attachments
iapetus-bump.png

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Post #4by Art Blos » 28.09.2017, 18:16

Is it possible to reduce the number of polygons to 256 or 300 thousand? To reduce the load on the system.
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Post #5by John Van Vliet » 29.09.2017, 02:53

you used a blur to fill in data

i used "resynthesizer" in gimp
https://github.com/bootchk/resynthesizer

as to less polys
-- maybe ?

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Post #6by Art Blos » 29.09.2017, 04:16

John Van Vliet < I have no experience with these utilities. You are better at this than me. You can simply reduce the number of polygons to 300,000 so that I can include Iapetus in "Celestia Origin"?
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Post #7by John Van Vliet » 29.09.2017, 05:05

so you want it BIGGER
it is already as 244615 verts and 244620 faces , but it is UV mapped

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Post #8by Art Blos » 29.09.2017, 05:13

John Van Vliet wrote:so you want it BIGGER
it is already as 244615 verts and 244620 faces , but it is UV mapped
I am guided by the number of polygons. Now 489 240, and I ask to reduce to 300 000. For a very detailed model this is optimal. Is it really not clear that I want to increase productivity? :insane:
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Post #9by CM1215 » 29.09.2017, 11:53

John, can you post this model in .obj format so that I can have my try at correctly orienting the texture?
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Post #10by Art Blos » 29.09.2017, 12:03

By the way, I would also not refuse the format .obj. Then we can independently reduce the number of polygons.
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Post #11by CM1215 » 29.09.2017, 18:57

Also, if you release the model in obj format, could it be non-UV-mapped? I would rather do the UV mapping myself.
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Post #12by FarGetaNik » 18.10.2017, 14:08

Does the model take oblateness into account? I can't really tell if the polar diameter is shorter than the equatorial diameter on this mesh.

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Post #13by Art Blos » 18.10.2017, 15:20

FarGetaNik wrote:Does the model take oblateness into account? I can't really tell if the polar diameter is shorter than the equatorial diameter on this mesh.
There's a difference of only 68 kilometers with a total size of 1492. Personally it seemed to me that everything was taken into account, although it is not easy to notice.
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Post #14by FarGetaNik » 18.10.2017, 16:08

Art Blos wrote:There's a difference of only 68 kilometers with a total size of 1492.

Well it's about 4%. You can definately tell it's oblate when looking at Cassini images, the fact that I can't with this model makes me believe it's not oblate. This is easily fixed if I retain my "Oblateness" parameter in the ssc file.

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Post #15by Art Blos » 18.10.2017, 16:14

FarGetaNik wrote:This is easily fixed if I retain my "Oblateness" parameter in the ssc file.
Better this way:

Code: Select all

SemiAxes   [ 746 746 712 ]
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Post #16by FarGetaNik » 18.10.2017, 17:21

Art Blos wrote:Better this way:
It doesn't matter, the result is the same :wink: I prefer oblateness on objects that have 2 identical equatorial axes.


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