Celestia Forums

Here is a little instruction of how to make a most beautiful 4k earth.dds file which has an 8bit alpha channel such that only the sea reflects the sun light.
Of course its is much nicer with 8k but since it needs DXT3 format the file is getting too large for my 32MB GeForce card.
I sketch the steps for gimp (Linux/Windows) but photoshop should be similar.

1) load your earth4k.jpg in rgb format and extract the three r,g,b channels as /greyscale/ images. You may first run an 'unsharp masking' filter on it to make it even more crisp.

2) Use 'select acording to color'
with a 20% fuzz threshold and click on an average sea color in earth4k.jpg which should select the sea around the continents. Then use the command 'save to channel'. In the /channel/ display, you now should have a map with sea being white and continents being black (=transparent in alpha later). Open a new white 4k /greyscale/ file and drag your new channel on it. This will be our new alpha channel controlling the specular reflections!

3) Now you go to image/mode/compose
(gimp) and select RGBA mode. Assemble the four files, return and you have your new earth4k file with a specular layer. Save it as a *.tga file.

4) In windows, convert this file with 'nvdxt' as follows:

nvdxt -file earth.tga -dxt3

Please note DXT3 (not DXT1a)!

5) use your new earth.dds file as usual and switch on vertex and pixel shading (CTRL V, CTRL P)

That's it, well worth the effort.
The respective earth.dds file is about 10MB since dxt3 compression is only 4:1 instead of 8:1. Anyhow this is a marvelous 'medres' texture...

Bye

Fridger

Cool!

What about earthnight4k/8k . Are they also using 8-bit alpha channel? I mean what nvdxt command line you use to convert them to dds?

Nice work Fridger! I hadn't actually tried using a DXT3 Earth texture yet--I'm glad to hear that it works as designed.

Pixel: there's no need to use an alpha channel for the night texture. The 8:1 compressed DXT1 format will work just fine.

--Chris

chris wrote:Nice work Fridger! I hadn't actually tried using a DXT3 Earth texture yet--I'm glad to hear that it works as designed.

Pixel: there's no need to use an alpha channel for the night texture. The 8:1 compressed DXT1 format will work just fine.

--Chris

Pixel: I was about to answer you the same as Chris...For people with "low memory" graphics cards (<32MB), it is worthwhile to produce a 4k black&white "earthnight.dds". It also looks very good...

Indeed, the specular hires effects are simply amazing. Under certain light conditions e.g the non-reflecting islands in the pacific with blue glare all around them gives a really magic atmosphere. Of course one needs a hires cloud layer, too;-). It is also worth experimenting a little with the "specular parameters" in solarsys.ssc. I prefer

SpecularColor [ 0.65 0.65 0.7 ]
SpecularPower 20.0

For beginners in this game: the higher the SpecularPower, the more /concentrated/ is the reflected light "spot". The higher the rgb values the brighter the reflection.

Another very worthwhile exercise with "gimp" or "photoshop" image manipulations is to generate a specular alpha layer producing magic reflections in the ice of pluto2k...

Finally, please note: my graphics card is almost old-fashioned by todays standards: GeForce 2 GTS with only 32MB. My computer is powered by a PIII 1Ghz/512 MB-CL2. Even with earth8k.dds+earthnight4k.dds I get always between 15-20 fps, a quite acceptable value.


Bye

Fridger

Anonymous wrote:Finally, please note: my graphics card is almost old-fashioned by todays standards: GeForce 2 GTS with only 32MB. My computer is powered by a PIII 1Ghz/512 MB-CL2. Even with earth8k.dds+earthnight4k.dds I get always between 15-20 fps, a quite acceptable value.


Bye

Fridger

Sorry for quoting myself;-).
I forgot to mention the resolution:

1280x960 with 16bitplane color.

It's a "small window" in my 1600x1200 screen;-)

Fridger

I have not been recently in space, but if i use the main image from BlueMarble:
http://earthobservatory.nasa.gov/Newsroom/BlueMarble/
as a reference image i think that
SpecularColor [ 0.60 0.55 0.4 ]
SpecularPower 35.0
are more close to reality. It is also worth the time to select more colors with gimp in "add" mode to define specular map more precise. I included also ice and snow areas to it. Have you tried the bump map in high resolutions? I see bumps, but they are not in place .
BTW my nvdxt.exe tool crashes every time i try to convert 8k textures. I am on Geforce2 Ti 64MB and i don't experience any slowdawns. Even prepared ssc file with 1000!! copies of earth, placed uniformly along earth orbit to form complete ring. All of them are dressed with 8k base texture.
Then Celestia hates me and craches often, but no slowdawns.

Pixel wrote:I have not been recently in space, but if i use the main image from BlueMarble:
http://earthobservatory.nasa.gov/Newsroom/BlueMarble/
as a reference image i think that
SpecularColor [ 0.60 0.55 0.4 ]
SpecularPower 35.0
are more close to reality. It is also worth the time to select more colors with gimp in "add" mode to define specular map more precise. I included also ice and snow areas to it. Have you tried the bump map in high resolutions? I see bumps, but they are not in place 8O .
BTW my nvdxt.exe tool crashes every time i try to convert 8k textures. I am on Geforce2 Ti 64MB and i don't experience any slowdawns. Even prepared ssc file with 1000!! copies of earth, placed uniformly along earth orbit to form complete ring. All of them are dressed with 8k base texture.
Then Celestia hates me and craches often, but no slowdawns.

I'll try those values you suggest...I also played with adding other colors for the specular selection, but somehow came back to the more simplistic one at the end. May try again...

I was not excited by using bumpmaps for earth so far, despite using 4k ones. I have virtually no crashes with nvdxt, despite heavy use. I had one when I converted the 97MB 8k greyscale moon.tga to *.dds when I prepared the *.tga file with Linux-gimp. After reloading/saving it with Windows-gimp everything worked fine!

Bye Fridger

Can some kind person post a screenshot for people stuck with a crappy Rage 128?

Would it be possible to support specular maps through a seperate texture, so that the ground texture can be compressed with DXT1?

*bump* yep...im making dds files from now on peeps btw chris can this be moved and stickied in the textures forum? thx...

Ok on adding bumpmaps I believe it was mentioned that this is not possible using one dds file due to a bug Fridger mentioned correct? But in the event I use this I would use dxt5 compression correct? And also the next question is how would I compile this using one tga file? or would I use 2? One RGBA and one RGB/Greyscale?...For now I will probably use multiple dds files

edit- I just had a crash using a bump map in dds format of equal size to the main texture using dxt1c compression....Was this the incorrect compression? The main texture uses dxt3...

Well Ill look further into bumpmaps....I think Im supposed to use dxt1a?....anyway I made my clouds and nightlights all dds format and wow the speed is way faster than even when I was using 2k jpgs!!!



There you go Fridger I have learned to use dds now hehe...

You don't want to use DXT compressed textures for bump maps. Not only does Celestia not support this, but limitations of the DXTn format itself make it very unsuitable for bump maps. DXT tends to encode rather 'choppy' images, whereas bump maps require smooth transitions from pixel to pixel. No games use DXT textures for bump maps . . . Doom 3 uses paletted textures for bump maps (actually for normal maps) . . . They provide 4:1 compression, vs. DXT1's 8:1.

--Chris

So even using it as one texture...spec, bump and land RGB wont work? damn suppose the tech is still a bit early....btw I cant wait for Doom 3

Rassilon wrote:So even using it as one texture...spec, bump and land RGB wont work? damn suppose the tech is still a bit early....btw I cant wait for Doom 3 :mrgreen:

Well, /static/ bumping does, of course, work in DXT format, i.e.
combining spec + rgb + bumping (at a fixed angle of light incidence) into a DXT3 file. That's what I have been doing now for quite a while...

Bye Fridger

Rassilon wrote:
There you go Fridger I have learned to use dds now hehe...

Indeed! A great view....

Bye Fridger

Aye thats what Im trying to avoid....Software rendered bumpmapping looks better in the 3D sense....These paletted bumpmaps might be an option to add once chris figures them out...But the initial course of things should evolve into one texture that does it all...Well I suppose in the next few years this will become a reality ...Your textures look beautiful with the static bumpmaps in of itself...I am wanting an even further approach unfortunately...I love pushing the limits sometimes....but these 'IBM clones' are so fragile hehe.

Wow,... I'm well out of my deapth here.
As most of those post, shot right over my head...
I know how to load up my "Micrografx Picture Publisher"
and twiddle a few knobs, but thats it....

But i know what I like, and that picture is very, very nice
Hopfully I might be up for download for us nooobs.

Not the earth...Pixels you have already And Fridgers well I leave the earth to those capable hands....Besides the best way right now to get the high end earths is to make your own...And really its not as hard as people are making it out to be....

The other systems I will be making will of course be different...I will be doing something like this:

1024 x 512 standard RGBA [red green blue and alpha textures in one] dds files for moons and generic worlds

2048 x 1024 standard RGBA for select chosen worlds in the dds format

1024 x 512 dds night textures

1024 x 512 or 2k cloud dds textures

then generally 1024 x 512 greyscale JPG bumpmaps....

I am currently testing all the compression rates and what not...Hoping to produce files small enough to share...

There MIGHT be the small chance I conjure up a few 4k(4096 x 2048) or even 8k(8192 x 4096) textures but I dont think I will share these on the fact I have no way to get them to the community....

Speaking of large Earth maps, I downloaded the BlueMarble maps from NASA. 16kx16k for each hemisphere. I've tried to combine them into one, gargantuan 32,768 x 16,384 pixel image, but my PC seems to have a low tolerance for pain.

Has anybody (Fridger) got this to work? I'm using an AMD Athlon XP 2100+ with 1GB PC2700 333Mhz DDR RAM. I also have a 120GB hard drive and I set it up with a 4GB page file (XP's upper limit), but Gimp still falls to its knees. The video card shouldn't even come into it, but I'm using a geForce 3, so it should be okay anyway.

I realize that a 32k texture is pretty much pointless, but its the principle of the thing!

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