Dry River-bed: a WIP --> please submit suggestions :)

[Tangled-Universe]

Hi peepz

This is a crop of a render I've been working on for almost a day. It took ages to fiddle with the strata settings and to make it all look good at the target rendersize and detail, which will be 1600x1200 @ detail 0.7 AA6 and without GI. As in my last fake stone image I've used a 9 sun lighting-array (see node screencap). Rendering this crop took about an hour.

As you can see I've put circles around some problem-areas where the displacements are messing up the geometry. It often happens that using the displacement-shader can create very distorted steep slopes. At some areas this has happened. I presume this can be solved by tweaking the strata tilt direction. So this is something I still need to try.
Anyone else suggestions?

I've also tried to create overhangs using the redirect shader or using a powerfractal on steep slopes (like in Haroon's canyon impression). Creating the overhangs isn't that much trouble, but stratifying (is that english?  ) the overhangs didn't work at all. The only results were very distorted steep slopes with spikes all over it.
I think it may have to do something with compute terrain node before using the strata-shader, but I couldn't figure it out. I've been trying gradient patch size from 0.1, 1, 10 to >20. All with no effect.
So again, anyone with suggestions?

Ok, further on...I'm pretty happy with the results so far, but as I mentioned it's a WIP so here are the things to do besides the problems stated above:

- Increasing size of small stones on steeper slopes and add slightly more detail.
- Add more detail and slightly more displacement to the bigger stones. --> THANKS Frank for your crack-technique, it's easy to work with! 
- Add dried mud/crack texture to the riverbed (bottom right).
- Add shrubs/trees.
- Working on colours, because they look a bit monotone/bland right now.

Well, that's it for now, let's get on with it
Please let me know what you think about it and I'd really appreciate it if you have any kind of suggestions.

Martin

[FrankB]

Hi Martin,

have you ever tried making all or most of your discplacements *before* the first compute terrain  node, so that you don't need a second one further down? Like in the attached project file?

Aside from that, I can't see what you mean by the encircled areas exactly. They don't look too messed up to me.

I have another thought on you regarding the image composition - My associative brain tells me that the larger stones are appx. 2-3 Meters high, so that the entire cliff is maybe only 20 m tall. Was that the proportions you had in mind? Also, the shapes sort of don't match what you would expect to crumble down from a cliff like this. It's difficult to be precise on what I mean by this, I'm afraid.

I'm also wondering why you need 2 strata shaders. In theory, the one strata shaders should also make you smaller stratas, depending on the number of octaves you specified.

Looking forward to see how the image develops.

Cheers,
Frank

[rcallicotte]

This looks great to me, so I'll just watch and learn.

[Tangled-Universe]

Hi Martin,

have you ever tried making all or most of your discplacements *before* the first compute terrain  node, so that you don't need a second one further down? Like in the attached project file?

Aside from that, I can't see what you mean by the encircled areas exactly. They don't look too messed up to me.

I have another thought on you regarding the image composition - My associative brain tells me that the larger stones are appx. 2-3 Meters high, so that the entire cliff is maybe only 20 m tall. Was that the proportions you had in mind? Also, the shapes sort of don't match what you would expect to crumble down from a cliff like this. It's difficult to be precise on what I mean by this, I'm afraid.

I'm also wondering why you need 2 strata shaders. In theory, the one strata shaders should also make you smaller stratas, depending on the number of octaves you specified.

Looking forward to see how the image develops.

Cheers,
Frank

Thanks for your suggestions and thinking

You're right about the encircled areas, they're not too messed up but I just couldn't get rid of them. It was a lot worse first so I'm pretty happy now but maybe someone like you knew how to solve it.

The image has a strange composition because it's a crop. I've attached a very rough preview of the final scene compostion.
You have a well developed associative brain because your estimations almost correspond quite well with the actual scale. Bigger stone size is about a meter and I'm still struggling a bit with those stone sizes. On second opinion I might decrease the smaller stone size and restrict them to less steeper slopes. Same for the bigger stones, decrease size a about a half. I intend to place 1m tall shrubs and max 5m tall trees. I think the scales will be o.k. then but that's always a surprise. How do you think about that?

The first strata-shader is restricted to the canyon-wall as seen in my first posted render.
The second is placed on a higher altitude and has a "dull" standard settings only greater depth and spacing. It's not visible in the crop I've posted.
So no, I didn't use it to get the effect you mentioned. Actually, the first strata node has 12 octaves and the second has 8.

I've just checked out the attached file. Thank you for that
At the moment I'm putting all terrain-displacements before the first compute terrain and see how that works out. I know it should work, actually can't tell why I did it this way haha
I'm also trying your way of getting the overhangs and see if my strata will remain the same.

While looking into your file I met a "new" node I didn't work with yet. It's the TEX coords from XYZ - node.
What is this node actually doing?
For other people reading this topic and myself I've attached 2 quick renders for comparison.
I presume it's similar to a compute terrain/normal? It looks like the strata work out a lot better/accurate with that node.

I'll post a new render with your suggestions a.s.a.p. Probably about 1 - 2 hours
Appreciate your help!

Martin

[FrankB]

Hi Martin,

here's an explanation on "tex coords from xyz", from the master himself:
http://forums.planetside.co.uk/index.php?topic=1249.msg12539#msg12539

I need this shader to tell the distribution shader to only allow stratas above a certain height. You'll understand once you've read Matt's article. Essentially your guess wasn't bad: in short, it does compute the terrain, but without re-computing the normals. In other words, if you need height information before compute terrain, you'll need this xyz node to give you that.

With regards to the scaling of stones, shrubs etc, your suggestions sounds ok, but as you said, we'll see how it works out only after you've done it ;-)

As for re-engineering a scenes displacements to before the compute terrain: from my experience, it is virtually impossible to get identical results: for whatever reason.
So you may not succeed in re-engineering your scene like this, but I have made it a habit now to always try to develop the displacements I want before the compute terrain from scratch.

Cheers,
Frank

[Tangled-Universe]

Hi Frank,

Thanks for the quick and dirt, yet clear explanation and the link
And yes, I've to rework all the displacements right now  so it will take a couple of hours more to get it the way I like...
I'll keep (all of) you updated.

Martin

[Volker Harun]

Hmmmm ... sorry for not reading the other constructive comments and thus ignoring them ,-)


I personally like the effect of the Strata and Outcrops shader - not. But yours look very good.
Have you tried alternative ways for the strata?

Those encircled displacements look rough (Colour Roughness issue?) - maybe inserting Function - Clamp could be a helper.

Just my five cents ,-)

[Tangled-Universe]

Thanks for your five cents and your mail Volker ,-) Very interesting strata-method. Luckily I have enough time to back-engineer it to see how it works. I admire your creativity with the nodes! I'll also take a look if the clamp function is of any use to me.

Martin