Celestia Forums

If anyone out there is lookig for a really nice Earth spec map,
with some of the most detailed rivers and lakes i've seen
then check out the new spec map from Mario at space-graphics.com

It really enhances a good earth texture, quite alot.
thr rivers running along the Amazon need to be seen.




Grab it from here http://www.space-graphics.com/downloads/maps/e43/e43_mask_type2_8k.zip

5.1meg

Enjoy

Shameless plug: I like my 32k VT spec map too!
(see www link below)

Darkmiss!!

Many thanks for the tip. The river details are fantastic. This spec map adds a new dimension to the Earth experience in Celestia.

I intend to use this spec map from now on.

I'd like to point out that Hawaii is missing from the map, but it can be added easily using Photoshop or some other graphic editor.

Again thanks for telling us about this major find.

Yep, definitely a great specular map, although it's only 8k. The biggest difference I find, other than the river detail, is that the ice sheets are speculared (is that a word? ) out. It's the same one that I use in my earth renders as well.

It's the landcover map from the Blue Marble source files FTP.

I used it for my texture as well. Hawaii and all deep atlantic/pacific/indian ocean islands are missing, because it was generated from the monthly 500m MODIS land albedo updates, which only cover the major continents and Indonesia.

A shame SG didn't bother fixing the problems.

You could make your own pretty easily with NetPBM and a little bit of Photoshopping like this:

1) Take an original color BM color texture (NOT THE ONE WITH THE CHLOROPHYLL TINTED OCEANS) in the desired size
2) Convert to 3 greyscales for the three color channels
3) Subtract the blue channel from the green channel.
4) Threshold the color curve of the resultant <green-blue> map, with every value 10 and below mapped to black, and every value 11 and above mapped to white. This gets all islands save one in you want in the south Indian ocean, while excluding all reefs.
5) Threshold the red channel, so that every value 36 and below is mapped to black, and every value and above is mapped to ice - this captures the sea ice and the one or two glaciated islands in the South Indian.
6) Add the results from steps 4 and 5 together. This merges the sea ice and island sets, but unfortunately blankets the continents with opaque/non-specular white.
7) Take the product of 6, go into Photoshop/Gimp, and erase (paint black) every continent except Antarctica, Indonesia and all islands within 5-10 pixels, which is the specular cover of the landcover map. Use your better judgement around Canada and Siberia, where the sea ice touches the land - probably better to just leave a slight overlap of the sea ice onto land here.

You now have a spec map with all deep sea islands and sea ice that should be rendered at your desired resolution. The thresholds in 4/5 are the ones I determined empirically from the default BM, but if you keep both original and the color separations open you can look at details to make sure the mapping looks right.

Except for part 7, theres little here that requires human intervention. So if you have scripting skills and Image Magick, you could easily do a 32k or upsampled 64k island/sea-ice spec map

8) Now, download the two landcover maps at Visible Earth Blue Marble sources FTP: [url]ftp://mitch.gsfc.nasa.gov/pub/stockli/bluemarble/
[/url]
9) Convert from 16-bit raw to your working image format.
10) Merge hemispheres.
11) Threshold value 0 to 0, and everything 1 and above (though it maxes at 15) to white.
12) Scale to your desired resolution.
13) Remap, so that all greys that might result from mixing during scaling are dithered to black or white. Using the NetPBM pnmremap with a two pixel .ppm mapfile (black and white) does this quite handily.

You now have a pixel perfect version of the landcover spec map at any desired resolution.

14) Add the products of 7 and 13, and you now have a specular map with all the the islands, sea-ice, and continental landcover in in whatever resolution you desire.

I've done this for you in 16 k, presented it a .png so further mods are easy, but note, the sea-ice present is based on merged MODIS sea ice cover masks, and not on the default blue marble color texture:

Right click to download - its only 745 kb for a map 4 times the size of SGs. He probably forgot to remap to just two colors, or is using the much less efficient .tiff compression, or something.

http://laika.012webpages.com/celestia/download/hp3.spec.16k.png

Named hp3 cause its from the 3rd public release of the home planet textures for the Orbiter simulator. Its a full 16k set that will be done in playable formats for Celestia real soon.

Looking forward to trying this one when I'm fixed!!

Regards...bh.

sombrehombre wrote:
...
http://laika.012webpages.com/celestia/download/hp3.spec.16k.png

I must confess, your 16k spec map does not excite me too much...have a look yourself (low quality spec's in the rivers!):

I guess I have to get at it myself...

Bye Fridger

> have a look yourself (low quality spec's in the rivers!)

At 16k, a pixel is 3.3 km accross. The upper tributaries of the Amazon aren't that wide. SG may have changed the way he splits ties (an 8k pixel has contributions from an average of 27.8 pixels of the 43k original), so that more pixels are mapped to black (water). I tried this to, but it 1) creates problems at the shorelines (the water generally rises to cover 1 pixel-wide band of the shorelines, and much detail is lost), 2) simply isn't accurate - see the films Aguirre or Fitzcarraldo and decide whether those tributaries are really 3 miles/6.6 km wide on average.

It's down to aesthetics. I had a result that with SGs rivers (continuous, yeah) and shorelines (no capes, peninsulas, barrier islands, or shorelines left, boo) entirely by accident, by scaling from 43k to 16k, breaking ties in favor of water, then scaling from 16k to 8k, and breaking ties again in favor of water. I decided that although I liked the rivers more, the shorelines weren't as good, and overall, the considerations of accuracy dictated that I take greater care that my scaled map was as close to a straight majority vote of ALL pixels in the 43k as possible.

If you wanted to, you could scale from the 43k 2 color, map grey values < 254 to black and ==255 to white, and you'll have land that looks like swiss cheese (every pixel at the 8k will be considered water if at least one of the 27.8 pixels its formed from is more than 50% water). Finland and Sweeden will look like the aftermath of the deluge, and may simply become a collection of islands. But by god, you'll be able to wade from the mouth of the Amazon to the Andes foothills without ever getting dry.

At anyrate - the goal of the post wasn't to parade my spec around, it was simply to point out that doing one from the same source Mario at SG is pretty easy at any desired resolution (all those steps won't take more than 2-3 hours at the 16k if you understand the capabilities of your graphics utilities). Second, if the lack of islands is the only perceived flaw in SGs spec, scale mine, erase the continents, and add it to SGs - It'll be a lot more accurate, and a lot easier, than trying to paint them yourself in Photoshop.