Live cloud maps

[juz10mac]

There is a Macintosh application called OSXPlanet that displays the earth with live cloud maps, downloaded from a server. Would it be possible to have Celestia import these maps? Could a script be run upon celestia's startup to download and update Celestia's copy of Earth's cloud map? I don't know what format the maps are in, or how compatible they will be. But I think that would be a pretty cool feature, and would definitely make things more realistic.

OSXPlanet: http://gabrielotte.com/osxplanet.html

[maxim]

There is also an w32 application named 'EarthBrowser' that displays live maps.

But this issue has been discussed already several times. I suggest to use the search engine to look for these threads.

maxim

[Christophe]

Yes this can be done with a short shell script.

In a new subdirectory of one of your extras directory put the following two files:

livecloudmap.ssc

Code: Select all

Modify "Earth" "Sol"
{
   Atmosphere {
      CloudSpeed 0
      CloudMap "clouds_2048.*"
   }
}

update.sh

Code: Select all

#!/bin/bash

cd $(dirname $0)
mkdir -p textures/medres/
wget -O textures/medres/clouds_2048.jpg 'http://SELECT_MIRROR/clouds_2048.jpg' && \
convert textures/medres/clouds_2048.jpg -negate -channel R -separate -channel A -combine textures/medres/clouds_2048.png
jhead textures/medres/clouds_2048.jpg

Select one of the mirrors listed on the Xplanet site.

You need wget, ImageMagick and optionally jhead to display the date of the map.

Make update.sh executable with "chmod a+x update.pl", run it, start Celestia.

[t00fri]

Hi Christophe,

I am afraid, my familiarity with Mac's is minimal, but it's nice to see from your post that they meanwhile seem to know by default about a UNIX directory tree structure and /bin/bash etc....

So is it correct then that our active Mac community here should better be fluent in UNIX command syntax? That would open up new perspectives...

Bye Fridger

[Jeam Tag]

Yes this can be done with a short shell script.

Is it only for mac? (I'm not a programer and all this terms sound like martian for me, sorry) Jeam

[Christophe]

Fridger, I haven't used OSX but I think the update.sh script should run on it. OSX uses by default a non standard directory structure with long names (/System/Library/ instead of /usr/lib/) but the standard Unix hierarchy is also there but not visible from the GUI. See this Ars Technica article. And yes, bash is included by default!

Jeam, this is for Unix like systems but it can easily be adapted for Windows. Wget and ImageMagick are available for Windows and update.sh could be transformed in update.bat but since I'm no cmd.exe wizard I'll leave it to somebody else.

[t00fri]

Fridger, I haven't used OSX but I think the update.sh script should run on it. OSX uses by default a non standard directory structure with long names (/System/Library/ instead of /usr/lib/) but the standard Unix hierarchy is also there but not visible from the GUI. See this Ars Technica article. And yes, bash is included by default!

Jeam, this is for Unix like systems but it can easily be adapted for Windows. Wget and ImageMagick are available for Windows and update.sh could be transformed in update.bat but since I'm no cmd.exe wizard I'll leave it to somebody else.

Christophe,

OK so we can expect our MAC people to speak UNIX
Excellent...at last some people who should understand your and my "mother tongue"

More seriously: Those downloaded cloads are in JPG format that is unable to handle transparency. Looks like a pretty dull "live" experience it seems to me...

We have discussed the issue of live clouds many times. The main argument against them was mostly the lack of transparency or --turned around-- the large amound of "bricolage" required to make them transparent after download.

Any better ideas??

Bye Fridger

[Christophe]

More seriously: Those downloaded cloads are in JPG format that is unable to handle transparency. Looks like a pretty dull "live" experience it seems to me...

We have discussed the issue of live clouds many times. The main argument against them was mostly the lack of transparency or --turned around-- the large amound of "bricollage" required to make them transparent after download.

I would rather say that the jpg file handles nothing but transparency. The grey level has to be mapped to the alpha channel which is what does the ImageMagick command. You may call it bricollage, but the result isn't that bad (I'm sure the process used to produce the collage is far more bricollagesque!)



I agree it's not perfect, there is a visible shadow arround land masses which comes from the upstream processing done to remove them from the satellite images.

[t00fri]

I would rather say that the jpg file handles nothing but transparency. The grey level has to be mapped to the alpha channel which is what does the ImageMagick command. You may call it bricollage, but the result isn't that bad (I'm sure the process used to produce the collage is far more bricollagesque!)

OK fine, that's trivially possible e.g with Image Magick, but was it the intention of the "cloud owners" that their clouds' gray levels are to be interpreted as alpha transparency information?? In other words are we making up here a cloud illusion that might look OK to the eye, but in reality corresponds to a quite different cloud scenario?

You see, as long as I am not linking my cloud texture to a particular date, I am free to interpret its gray levels as alpha, since all is "generic" anyway.

But as soon as I say: This was the Earth's cloud coverage on August 8th 2005, 22:17 UTC then the claim for "rigor" of rendering changes substantially....Can you see my point?

Bye Fridger

[juz10mac]

Yes this can be done with a short shell script.

That's great. Thank you all for your replies.

But this issue has been discussed already several times. I suggest to use the search engine to look for these threads.maxim

I'm afraid I didn't find this before because I was specifically looking for a mention of OSXPlanet. I'm sorry if I double threaded.

[Christophe]

Point taken. Let's compare to the meteosat visible shot:

(Map dated 2005-08-08 18:30)



With a little tweaking I think you can get something very acceptable.

[t00fri]

Point taken

perhaps it's worth tweaking this further....
I'll play with it a bit soon.

Bye Fridger

[Kolano]

"You keep using that word. I do not think it means what you think it means."

Bricolage

1. Something made or put together using whatever materials happen to be available: ?€?Even the decor is a bricolage, a mix of this and that?€

[t00fri]

"You keep using that word. I do not think it means what you think it means."

Bricolage

...

I guess we agree that the word 'bricolage' is a proper French word. Christophe is French and my feeling is he understood the meaning exactly as I meant it. While my French has become pretty rusty, I once carried a French passport at least .

In any French-German dictionary 'bricoler' is translated as 'basteln'. Basteln is what many kids enjoy, a form of 'do-it-yourself' with materials that happen to be at hand, but it's certainly NOT the professional way of realizing something.

Bye Fridger

[Jeam Tag]

"You keep using that word. I do not think it means what you think it means." Bricolage

In any French-German dictionary 'bricoler' is translated as 'basteln'. Basteln is what many kids enjoy, a form of 'do-it-yourself' with materials that happen to be at hand, but it's certainly NOT the professional way of realizing something. Bye Fridger

This is the way i've understood your message, Fridger, you're right. We have an idiomatic that is following this notion, too: the 'Syst??me D', where 'D' means 'D?©brouille'. You can understand that like the Mc Gyver's 'Bricolages' for example!

Christophe, thx for the explanations, noted, i'll try to understand and apply them. Jeam

[Christophe]

Yes, I perfectly understood what Fridger meant when he used bricolage. The very useful Grand dictionnaire terminologique gives do-it-yourself(ery) as a generic translation, a word that in itself in a very saxon way looks like bricolage to me ;-) In the CS field the correct translation is kludge.

[t00fri]

Yes, I perfectly understood what Fridger meant when he used bricolage. The very useful Grand dictionnaire terminologique gives do-it-yourself(ery) as a generic translation, a word that in itself in a very saxon way looks like bricolage to me In the CS field the correct translation is kludge.

Christophe,

thanks for confirmation .

Back to the interesting live clouds issue. While thinking more about this and the great possibilities of ImageMagick batch processing, I can see room for considerable improvement.

Take my old and pretty well-known 2k clouds as an example. There I used quite a number of image manipulation tricks to make them loock fluffy and to suppress their 'digital' appearance at close distance etc. There was also a bluish gradient layer becoming denser near the poles etc. Also I applied a displacement map to the whole configuration finally.

The main point however is that my clouds surely also used an alpha layer with transparency given by some simple grayscale cloud pattern.

For the live clouds all these additional features could be prepared once for all just like in my old clouds. All that would be replaced from time to time via a shell script is the alpha layer!

ImageMagick can do many many subtle image manipulations at the batch level. So even 'unsharp masking' or displacement maps could be applied via batch as a last step...

Bye Fridger

[ElChristou]

The idea of live clouds can be a nice option...

***

I have just tested this little soft, and... ...I'AM FURIOUS!!!!!

The shadows of saturn rings are perfectly rendered meanwhile in Celestia my board is suppose not to be able to draw them...

[alphap1us]

Hi Fridger and Christophe,
FYI, any shell script that you write which is portable across different linux distros should work without any problem on Mac OS X. The usual /usr, /var, etc/ directories are there. They are just hidden from the Finder (the file browser) becuase they are very few actions you would want to do on them with the Finder. Everything is accessible with the terminal, as usual.

Cheers,
Joe

[t00fri]

Hi Fridger and Christophe,
FYI, any shell script that you write which is portable across different linux distros should work without any problem on Mac OS X. The usual /usr, /var, etc/ directories are there. They are just hidden from the Finder (the file browser) becuase they are very few actions you would want to do on them with the Finder. Everything is accessible with the terminal, as usual.

Cheers,
Joe

Thanks for the info, Joe. I didn't know that!

Bye Fridger