Adding snow to Furahan texturemap

[Coen]

... you can take into consideration the things I have done with my Terraformed Mars texture. Estimate the amount of Hadley cells per hemisphere, and atmospheric density, the trade wind routes and how high altitude landmasses effect the way the wind and weather will move around the forms and the end result for vegetation and rain fall.
Don. Edwards

That's exactly what I would like to be able to do, but cannot. I tried to get a feeling for such effects, and learned quite a bit from another website (on alternate history -I'm 'Coen' in that thread too- http://www.alternatehistory.com/discuss ... hp?t=84999) but then found myself staring at Earth maps and not understanding why some areas are dry and barren where I would expect them to have some moisture being blown in (say the Eastern coasts of Somalia/ Arabia).

So I never felt I obtained a decent understanding of Earth's climate, let alone predict climate elsewhere. Perhaps it is too far removed from what I know already, or perhaps I simply did not spend enough time or effort.

I guess there's a vacancy for someone to explain such climate effects; after texture colouring, perhaps?

[Coen]

It took a while (spent on something else) but I did produce some seasonal maps in the end. I used the Matlab routines I wrote about earlier to produce snow maps for the Northern as well as the Southern winter, and imported them into Photoshop as layers.

Then I had to think about sea ice. Both the polar areas on this planet differ from those on Earth: on Earth, there is either land on a pole, or the sea is largely land-locked. But what do you get when the polar areas are almost entirely made up of open ocean. I tried to find out, but did not manage to find anything suitable. In the end I decided on small ice caps that grow from local small islands (or in case of the North pole from a continent). They are small because of a moderate axial tilt and because of the termpering effects of the open sea. In fact, they disappear completely in summer.

I haven't yet played around with changing the colours of the land according to the seasons. I did make the map a lot darker though, but probably less dark than Don advised so you would still see something here. For Celestia I will darken them some more.

First, the one with winter in the North (you can't reaaly see where the maps end in the North, but you get the idea):




With as the logical next, winter in the South:




And finally, a detail:




I hope you like them; if anyone knows more about the likely nature and size of seasonal ice caps on an Earthlike planet with a moderate degree of axial tilt, I'm listening...

[Don. Edwards]

Hey nice to you are progressing nicely. There are two things I might suggest to improve on your texture.
1. The polar cap edges along the ocean are are little to smooth. They should be a bit more irregular with possibly some broken ice flows along there edges.

2. A trick I learned a few years ago when I made the first seasonal maps of Earth before BlueMarble did it by satellite photos. Use your ice/snow layers as a mask and select the corresponding land under them. Them copy the selected area into a new layer and take the saturation level down. If you look at any satellite pictures of snow and the ground, the surrounding areas look almost desaturated by the snow and ice cover. This also helps the illusion of dead or seasonal varying vegetation. Play with it a little and see how it looks. Because its a new layer you can adjust its opacity over the main texture until you get just the right look. Having the ice layer laying right over all that greenery just is not very realistic. Seasonal variation is a tough thing to implement. Its just not plopping some snow and ice on the texture. Its as you said, all the finer things such as the changes in vegetation and even the amount of light the polar regions are receiving. Also the the planets inclination will have allot to do with the seasons. An inclination of say 20 to 25 degrees would give you a fairly Earth like seasonal variation. Beyond 25 and you are going to start to see some very wild seasonal changes. Under 20 and the seasonal changes would start to be less noticeable. Of course you can take a planets orbital eccentricity into account as well. Take the Earth, our orbit is far from circular. It just so happens the when Earth is at its furthest distance from the sun the its winter in the southern hemisphere. Of course over time this does shift, but very slowly in our terms of time.

Just a few more for you to consider.

Don. Edwards

[Sen]

How would one go about creating such photo-realistic texutres? IMO, all the planet textures i've made so far look like crap. I cut and paste landmasses from Earth, mainly, and try, in vain, to make coastlines. How do you make those perfectly natural coastlines and deserts?

[Coen]

Dear Sen,

I was away; sorry for not replying earlier.

One part of what I did is texturing, and many people here do that a lot better than I can. I can only give you an outline: get images of Earth from NASA's Blue Marble, and cut and paste sections onto your own map. With graphic software such as Photoshop, you can use the 'clone stamp' tool to bridge the bits between the pasted sections. If you have a layer showing the sea on top, you can work on a land layer underneath, so the shores will always look nice. I sat and looked a long time at how the textures of Earth look like, and how they merge from one into another. If mine look more or less convincing, that is not because I did set out to do anything alien, but to do something Earthlike. But read the tutorials and all the other comments here. Why not try to mimic a true texture, say part off South America, with bits from other continents?

How did I make my coastlines? With a lot of work, literally. I already had rough shapes for my continents, so I needed to add detail to them. What better way than to use fractals? So I wrote a program in Matlab that did just that (I program for fun, not for work). I could have done it by hand, and in the end that might have taken just as much work...

Here too I studied Earth a long time, helped by a good atlas. Part of the trick is probably to avoid having all your coastlines look more or less the same, with the same fractal roughness. Look at the coasts of Western South America, and compare it to the coasts of Canada or Europe, particularly Norway (didn't someone get an award for those fjords?...)

Anyway, I used my program to design stretches of coastline with varying roughness, but you can do it by hand. Here is an example of how I did it. You can see that there is a big difference in roughness on the two sides of the island currently being edited. If it looks like Patagonia, that is no coincidence. The program is in Matlab and will not run without that.

I hope this helps a bit.

[Dollan]

I don't have anything meaningful to add to this thread, save that having been gone from Celestia for so long, I was thrilled this morning to come back and see that the creator of Furaha has joined this group, and is working on a model for his planet.

The Furaha site has been a favorite of mine for a long while and, together with the famous Epona, served as both model and inspiration for some of my earliest attempts at creating fictional but realistic planets. I can't wait to see how this particular project develops!

...John...

[zhar2]

Dollan i rember u'r textures for OA (and in ur own universe or arcbuilders), nice to see u, hopefully in OA too.

[Dollan]

Dollan i rember u'r textures for OA (and in ur own universe or arcbuilders), nice to see u, hopefully in OA too.

Thanks! I'm trying to get to a point where I can work on those things again, but I've a lot of juggling between work and what not before I get there.

...John...

[Sen]

Thanks Coen-

I found a nice way to add coastlines in gimp. It's a little lengthy, so I think i'll write up a tutrotial on it later. It involves using gimp, copies of spec maps, and of the original planet map. works very well I think.

As for continents, you're right. Cutting and pasting from Earth and then cutting out fine detail makes a more convincing texture.

[Hungry4info]

As for continents, you're right. Cutting and pasting from Earth and then cutting out fine detail makes a more convincing texture.

Far too often, I can look at a fictional extrasolar planet and make out my house =|.

More seriously though, it is often easy to see, for common example, the great lakes, in people's fictional work.

[zhar2]

Thanks Coen-

I found a nice way to add coastlines in gimp. It's a little lengthy, so I think i'll write up a tutrotial on it later. It involves using gimp, copies of spec maps, and of the original planet map. works very well I think.

As for continents, you're right. Cutting and pasting from Earth and then cutting out fine detail makes a more convincing texture.

Coastlines are rather easy but time consuming, normaly i generate a plamsa cloud in gimp then colored the color i want, use the spec map as a guide and paint out the unwanted plasma in pink and the use ut as an alpha channel, then paste it on the texture and for a bit more detail a thin edge detection colored in the wanted blue could be pasted on top too.