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Terrain integration, step 3

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I'm still progressing. Last week i've been doing a lot of work on the atmosphere shaders (will that stop one day?), especially the parameters at sunset. Another thing i still have to do is the transparency of the atmosphere at night, since at the moment it's fully opaque (so all you see is black, you can't see the stars).

Betelgeuze, a user on my forum, has been kind enough to make some texturing work, and i must say it's promising. He is working on some ground textures mostly for non-Earth like planets (since i've acquired a texture pack for Earth terrains). He's also working on some DEMs (digital elevation maps).

DEMs i hear you say ? "But i thought you were generating your planet procedurally".. ? And you're right, of course, but one problem with generating a procedural planet is that it's lacking "personality". So, what i plan to do is to generate a set of DEMs and to spawn them randomly on some planets, to make some places more interesting to visit. When spawning the DEMs, some parameters can be changed (for example: the type of terrain on which they are placed, can be perfectly flat, or already composed of hills or mountains; or their scale, etc.. ) which means that even if two planets use the same DEM, they will look slightly different. The DEMs themselves are pretty small, so they're covering a very small area of the planet (generally around 50 to 100 kilometers wide), but i hope that will be enough to give more style to the planets, and interesting location points to generate some cities.

This week i'm going to continue on the terrain, trying to fix the seams, and hopefully next week i should start on integrating the detail textures.
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It's a problem for your project (and any procedural system) I was thinking about over the weekend strangely enough. The challenge to get your shaders right is one thing, the challenge to make the universe interesting is quite another.

I don't think there is an "interesting feature" fractal you can code, so unfortunately you will need to implement some content. Happily, most players will be super-happy just to fly over the terrain and land on the surface to sit and watch the sunset. :)

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[wow] That looks pretty damn awesome. I've just spent the weekend in the Lake District - been wandering up/down mountains and generally getting very wet. I always find that spending time in the mountains makes me want to pick up work on one of my many attempts at a terrain engine - I'll settle for looking at your one instead [grin]

As for your use of DEM's and having some 'hard coded' features in your world - I think that's a great idea. There's a lot of potential for that to look *amazing*. I saw a demo years ago that took in a greyscale heightmap and used it as a seed for a random terrain generator. You'd end up with a different map each time, but every now and then you could spot bits that were in the original dataset or were very similar to them.

Keep up the good work!
Jack

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Hey it's the first time I post a comment here, so I guess it's mandatory that I say: I've been reading your blog for quite some time and I really appreciate your work! Keep going, you've got quite a crowd of fans, and you deserve none less :P

Interesting features is very hard to get right. Your last images are interesting enough for a computer game, but I suspect you want it to be photo-realistic :)

There was a time when I was really interested in erosion simulation models, so I researched a lot on them, although I never got round to implement my own ideas. What got me so interested in them was that, well, all the screenshots *were* interesting!! I mean, if you see some perlin noise-generated terrain side by side with the same terrain after some iterations of erosion, the differences are amazing!

The only downside is how costly these calculations are. Some "empiric" models (read: not based on complicated systems of equations) looked just as good as the other ones, but with a speed increase of orders of magnitude; however, it was still considered slow last time I checked. But since you're aiming for a computer of the future, this might be worth considering -- the most notable works were tested on computers from 1995 or something.

BTW, I really like jollyjeffer's idea ;)

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While I know that you are hard at work at getting earth like planets, I did noticed that said Betelgeuze is working on non-earth textures. Are/will you be doing gas based planets too?

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Quote:
Your last images are interesting enough for a computer game, but I suspect you want it to be photo-realistic :)


No, not really photo realistic.. but as long as i see some areas for drastic improvement, i'll continue.

Quote:
There was a time when I was really interested in erosion simulation models, so I researched a lot on them, although I never got round to implement my own ideas.


The main problem with erosion models, is that all of them require knowledge of adjacent heights. I do have these in a terrain patch, except on the seams, where the "adjacent heights" are actually in a different terrain patch (maybe with a different LOD). In addition, i'd need the ability to recalculate erosion on-the-fly. I don't think any erosion algorithm can do that..

However, if you can find a function of the height and world position, that returns a new height "simulating" erosion, i'd be interested, ie. h' = f(h, x, y)

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Are/will you be doing gas based planets too?


Yes, although you probably won't be able to "land" on them (the pressure will make your ship explode if you go too deeply, same for the suns).

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You're right in all those points. They DO make it hard to use such an algorythm in a game, that's why it's not used! I would love to have a function like you described, but I don't see that happening in the near future... From what I've gathered, it's an integral that can't be solved analythicaly, so you *have* to simulate it step by step, you can't just turn it into a function.

Well, this has rekindled my interest in this sort of stuff, so I'll look a bit more into it :) Maybe I'll try some of my ideas, meant to solve exactly the problems you mentioned. Anyways, here's a link to a nice animation of erosion at work:

http://www.best.com/~beale/landscapes/mpeg/erode3.mpg

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The main problem with erosion models, is that all of them require knowledge of adjacent heights. I do have these in a terrain patch, except on the seams, where the "adjacent heights" are actually in a different terrain patch (maybe with a different LOD).

I tried a bit of a hack for this in my attempt at planet rendering, just by generating one additional row or column of vertices at each edge of each terrain patch (to make normal generation simpler). I don't think it is a good solution though, as memory usage and patch generation speed is already a problem with my planet representation.

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The mountains... that snow... Stil lcould be improved on, but all I can say tat the moment is... Holy WOW!

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