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[KW71]

Would be possible to have an alternative way to create rivers, where just the water surfaces is added without altering the terrain? That would be useful if there are natural channels because the intrincated details could be preserved, not only on the edges, but also, for example the existent natural islands (like in this Acetone's Talkeetna screenshot).




Edit:

For nonexistent (or bad defined) channels, perhaps could be possible mantaint the detail "pushing" the terrain, instead of digging.



Just throwing ideas with the best of the intentions, guys. Hope some are useful.

[cameni]

The problem is that satellite radar data only contain height of the surface.

What we are going to do is taking water mask data and imprinting river and lake beds during the elevation dataset compilation. We will also capture the surface height for the water mask pixels, and use it to modulate the global sea level, creating lakes and dry areas below the sea level.
It will also make large rivers, as long as the width is at least 30-60m.

[KW71]

Just to clarify, when I say "where just the water surfaces is added without altering the terrain?", I mean using the roads tool... The rivers would still be vectors.

[cameni]

It would be possible, but it would mean that you are setting the water level slightly above the real one.

But you gave me an idea ... maybe we could make the river beds so that only the terrain that's already below the water level gets pushed down.

[bomber]

So would this be like creating a water table, and then pushing the terrain down to reveal the water?

[KW71]

So would this be like creating a water table, and then pushing the terrain down to reveal the water?

Yep... Something like the Blender screenshot... The point is that pushing the terrain instead of digging,  would keep the shore's detail...

Edit:  I mean pushing the middle of the river with a soft falloff.

[cameni]

What's the difference between pushing and digging?

[KW71]

Ah, just edited that in my previous comment.

For example, in Blender I select the middle vertex with "proportional editing mode" (soft selection in Max)enabled and push them down...

That way you are taking all the detail in the terrain and lowering it... the shores remain wrinkled. The fall of could be sinusoidal.



 

[KW71]

...Not sure if that is doable... The far I went with Opengl was creating furniture for Archicad...   

[cameni]

Well .. that's basically how I deform the terrain for river beds. In that sense digging in OT is just pushing down + applying a different material.

[KW71]

I thought it was a different method because I notice the detail on the shores and under the water is gone.

I have been playing with the transitional area trying to achieve better results. In this screen, for example, there is a nice detail at the end of the transitional area, but is far from the water...



If the water could touch that shore, would take their shape...

In this case I deleted the river, but the water was not erased... look at the nice (imo) borders...



I guess you got the idea... Is just that IMHO the borders looks a bit artificial, not like a river, but like an irrigation canal:

[cameni]

That's because it also modifies the transitional areas to ensure the shores are higher than the surface, to ensure the water doesn't look like held by invisible walls. However, right now it levels the terrain in the process. Ideally, on borders it would only pull up the terrain that's below the water level, while within the stream it would push it down.

[KW71]

"maybe we could make the river beds so that only the terrain that's already below the water level gets pushed down".

I bet this will make a great difference! 

[Acetone]

Some thoughts, not sure if that will help.
I agree with KW71, the rivers looks a bit like a canal. It's not a bad thing because it's probably simpler to start this way, but they sure looks man made. I was wondering what parameters could be used to make them looks more natural.

So far, I see a big difference between streams and large rivers. The smaller a river is, the lower it's impact will be on surroundings. As a result, streams will typically "dig" into the terrain rather than have large banks, especially because the water flow generally faster in these.
Here is a small example for a tiny one:



However, the aspect of a river is really dependent of the type of terrain it is on.

This one sits on a rock bed. As it can't really dig into it (especially with some types of rocks), so the stream is larger and not very deep. There are still no banks but rocks are really visible. I guess it's almost impossible right now to handle these two types of rivers, because it will need a lot of local parameters. But something between these two seems good. The most important is: almost no banks/transitional area, and visible rocks, low depth water. Like that:



Or that one:



The larger the river is, the larger the bed becomes and banks start to be more visible. You can expect a large transitional area between normal terrain and the river bed, and the river banks are generally made of pebbles, sand and some dirt, most of the times mixed together:



The river is also deeper. The big problem here to make it looks natural is that these areas are never consistent in terms of symmetry. You never see a straight bank, sometimes a tree will grow in the middle, sometimes there will be a large patch of sand and dirt in the middle of pebbles. And most importantly, a river never has symmetric banks in terms of width. It can work with a straight line river, but as soon as there are meanders, you can expect a large bank on one side, and almost not on the other side.



At the end, I think border/transitional and depth parameters should be proportional to the river width. If you manage to add procedural rocks in it, it will probably looks more natural. The big question is the symmetry one, because I guess it's something really difficult to do with the current vector system.

That being said, I think that as an alpha state new functionality, it's already an impressive addition to the engine

[2eyed]

So much impressive variations on one theme, I think nature can't be beaten by a computer program. Way too complex.

I did not manage to alter the river water colors without affecting color of the sea. The water also should be more transparent and for realistic appearance world/sky  reflections are needed.