Earth without oceans

Description: Tips for creating and manipulating planet textures for Celestia.

Adirondack M
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Adirondack M
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#1by Adirondack » 07.09.2006, 11:11

I've made an Earth texture (jpg & dds/mipmap) without oceans as if the oceans were removed suddenly.
Check it out here

Please note that this is my very first attempt to provide a texture. So don't call me silly if the texture doesn't fit to your taste.

Adirondack
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rra
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#2by rra » 07.09.2006, 12:49

Adirondac , I don't know how you did this, and I also assume that
the ocean-floor is not fictitious ,
but: is it possible to get a higher resolution (2K , 4 K , ... ) version of
this map ?
Combining this with a normal or bumpmap of the see-plane would be great.

Anyway , it looks very nice,
thanks for the upload .


René

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#3by phoenix » 07.09.2006, 12:56

yes it's a really cool map and I'm also interested in higher resolutions ;)
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Malenfant
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#4by Malenfant » 07.09.2006, 13:32

It'd be interesting to take this to the next level - instead of having the obvious green continents and brown seafloor, try showing what the earth would really look like with no water at all. So there'd be no ice and no vegetation.

Or maybe you could have it with no vegetation but with ice (like Mars), so the ice would cover the whole of the upper latitudes (seafloor included) and high areas.
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t00fri
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#5by t00fri » 07.09.2006, 17:16

Don't you remember that I did this already LONG ago (in 2003!)?

Here's a reminder:

Image
Image


Image

There are more, of course...
Image

rra
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#6by rra » 07.09.2006, 17:24

Fridger,

are these maps available for us users ?
(and if so,how can I get one ?)


René

ajtribick
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#7by ajtribick » 07.09.2006, 17:49

Maybe it would be a good idea to have the ocean floor as an overlay texture in the actual distribution. What kind of quality is the available data?

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#8by Malenfant » 07.09.2006, 18:31

The colouring on these maps isn't realistic though (even on Fridger's), because you can see a definite dark/light boundary at the edge of what was the continental landmass, that makes it look different to the paler material on the continental shelf.

There's no real reason for this - if earth's water suddenly disappeared and you came back to the planet a few thousand years later then I think one would expect the surface to look a lot more homogenous in colour. And a lot greyer too, since the ocean floor is made of basalt which is not pale brown in colour.
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#9by t00fri » 07.09.2006, 19:13

rra wrote:Fridger,

are these maps available for us users ?
(and if so,how can I get one ?)


René

Rene,

in principle: of course, YES. In practice: unfortunately, I have no idea where the respective cylindical projection textures got lost. Remember, I did these 3 1/2 years ago (!) in about 30 minutes of playing with GIMP ;-)

Since I don't take this sort of game really seriously, I havn't stored the originals in some safe place.

Of course they may be made much more "realistic" with further work.

Bye Fridger
Image

bh
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#10by bh » 07.09.2006, 19:17

Hehe...I remember them fridge! I also remember Darkmiss did some bathymetric maps around the same time!
regards...bh.

Johaen
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#11by Johaen » 07.09.2006, 19:18

I personnaly like Adirondack's texture. I think it's a good idea to have the earth as it looks now, just minus the oceans. As if all the sudden, poof! the oceans disappeared, and you looked at it then, not 1,000 yrs later. And I agree with a few of the others, a higher resolution texture would be neat to have, and maybe a bump map or normal map.
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scaddenp
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Re: Earth without oceans

#12by scaddenp » 07.09.2006, 21:14

What is your data source for the sea floor? (I can see it is not ficticious). The
best global bathymetry I know of is
ftp://falcon.grdl.noaa.gov/pub/walter/G ... _blend.bi2

Its a 1minute blend of the Gebco bathymetry (properly registered) with the
smith and sandwell predicted bathymetry grid derived from gravity inversion.

Adirondack M
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#13by Adirondack » 07.09.2006, 22:17

Malenfant wrote:...instead of having the obvious green continents and brown seafloor, try showing what the earth would really look like with no water at all. So there'd be no ice and no vegetation.
Or maybe you could have it with no vegetation but with ice (like Mars), so the ice would cover the whole of the upper latitudes (seafloor included) and high areas.


What do you think about this version:

Image

This is the current version in comparison:
Image

Unfortunately I'm not able to provide a higher resolution. :cry:
If you want to use a higher resolution -> use Fridger's.

@Fridger:
I didn't know that you ever did something like this...

Adirondack
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The horizon of some people is a circle with the radius zero - and they call it their point of view. (A. Einstein)

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#14by Malenfant » 07.09.2006, 22:27

That looks a bit better... you still have the dark continents though. There's no reason why what is currently "land" should remain such a different colour to the continental shelf (or the seafloor, for that matter. Sure, there's sediments on the shelf and on the seafloor, but they're not going to look THAT different to what's on a dry, barren surface that was formerly "land".
My Celestia page: Spica system, planetary magnitudes script, updated demo.cel, Quad system

ajtribick
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#15by ajtribick » 07.09.2006, 22:29

Isn't it that the continents are mainly granitic and the oceans mainly basaltic? If so, wouldn't the oceans have darker rock (on average) than the land?

t00fri
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Re: Earth without oceans

#16by t00fri » 07.09.2006, 22:53

scaddenp wrote:What is your data source for the sea floor? (I can see it is not ficticious). The
best global bathymetry I know of is
ftp://falcon.grdl.noaa.gov/pub/walter/G ... _blend.bi2

Its a 1minute blend of the Gebco bathymetry (properly registered) with the
smith and sandwell predicted bathymetry grid derived from gravity inversion.


Certainly, the latest Gebco data represent the best available bathymetry. Back in 2003, I also used the available Gebco data, of course.

Just getting a bit curious from this discussion, and given my new powerful normal map tools, I quickly did the following interesting exercise:

I use DIRECTLY the binary bathymetry data in (signed) 16bit integer format that Reto Stoeckly/NASA/BMNG recommends. This way there will be NO noise whatsoever in my resulting normal map!

http://snowy.arsc.alaska.edu/nasa/topog ... 801.bin.gz

The descriptive paper is here. Most of us know it by heart, I suppose...
http://snowy.arsc.alaska.edu/nasa/bmng.pdf

The biggest available size of 21600x10800 is a bit small for my taste ;-) but this way the making of a noise-free, highest-quality normal-map of the sea-floor only takes 1.5 minutes with my nmtools ;-)

Starting from the gzipped input bathymetry data file
gebco_bathy.21601x10801.bin.gz, the entire process of unpacking, reducing to the nearest power-of-2 size (16k), the required big-endian -> little endian flip and finally the normal-map generation is just one piped command on any platform (Win32, Mac-Osx/Intel, Linux):

Code: Select all

gzip -cd < gebco_bathy.21601x10801.bin.gz | resc2pow2 21602 1 | nms 6378.140 16384 2.7 > gebco_bathy_nm16k.ppm 


The ppm format of the resulting normal map can then quickly be converted to jpg or png e.g. with GIMP.

++++++++++++++++++++++++++
So, I was curious how the sea floor looks like for 2 oposite illuminations by the sun (no water of course!)
JUST rendered with this hires normal map!?
++++++++++++++++++++++++++

Here is the amazing result from a small field of view to exhibit the large amount of detail:

Yeah, as you can see, the sea-floor is still wet, since I pumped out the water just a few minutes earlier ;-)

Image

and with the sun illuminating from the opposite side, it has dried quickly ;-)

Image

Not bad, not bad,...

Bye Fridger
Last edited by t00fri on 07.09.2006, 23:40, edited 1 time in total.
Image

scaddenp
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#17by scaddenp » 07.09.2006, 23:38

[quote="chaos syndrome"]Isn't it that the continents are mainly granitic and the oceans mainly basaltic? If so, wouldn't the oceans have darker rock (on average) than the land?[/quote]

Seems reasonable to me depending on what weathering processes want
to assume. You probably want to regard things with less than 300m of
water as "land" (continental extension).

scaddenp
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Re: Earth without oceans

#18by scaddenp » 07.09.2006, 23:43

[quote="t00fri"]
Certainly, the latest Gebco data represent the best available bathymetry. Back in 2003, I also used the available Gebco data, of course.
[/quote]

Straight Gebco 1min grid has some known problems and is information-poor compared to the Gebco SS blend. The blend fixes the registration problem as well as adding in the detail only visible in SS.

t00fri
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Re: Earth without oceans

#19by t00fri » 08.09.2006, 00:20

scaddenp wrote:
t00fri wrote:Certainly, the latest Gebco data represent the best available bathymetry. Back in 2003, I also used the available Gebco data, of course.

Straight Gebco 1min grid has some known problems and is information-poor compared to the Gebco SS blend. The blend fixes the registration problem as well as adding in the detail only visible in SS.


I am sure Reto Stoeckli the leading BMNG analyst from NASA, with whom I was in contact again recently, has recommended to me the best data, namely the ones used for their analysis as well.

What's the format of the Gebco SS blend data you had referenced? bi2 looks kind of strange. I do need 16 bit integer binary data, otherwise the normal map becomes too noisy, loosing much more detail...

Bye Fridger
Image

scaddenp
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Re: Earth without oceans

#20by scaddenp » 08.09.2006, 01:24

[quote="t00fri"]
I am sure Reto Stoeckli the leading BMNG analyst from NASA, with whom I was in contact again recently, has recommended to me the best data, namely the ones used for their analysis as well.

[/quote]

I have no idea of the extent to which NASA tracks the discussions in the
bathymetry world. The blend is known to Gebco - see http://www.ngdc.noaa.gov/mgg/gebco/scdbxxi.pdf
page 7

You can see comment by Walter Smith (who made the blend and was
chairman of GEBCO subcommittee on digital bathymetry) at
https://listserv.hawaii.edu/cgi-bin/wa? ... R4305&I=-3

As always there are pros and cons with these data sets. The validity of
grids based on contours versus soundings is perennial topic with GEBCO data set. In areas without many soundings it is bare. In contrast, the SS predicted bathymetry has a truly global signal but also many artefacts. The fundamental data is satellite altimetry from which a gravity map has been derived. This is combined with crustal models and soundings and inverted for bathymetry. We are happy to live the artefacts because we
value the higher information content.

As to the data itself, it is 16bit integers (what bi2 refers to) at 1min
lat/long intervals. Registration is -180/180/-90/90


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