Classic Erosion Sediment Filled Valleys

Started by SuddenPlanet, December 21, 2021, 11:32:42 PM

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SuddenPlanet

I have been trying to figure out if there is a way to erode the valley portion of the terrain without using Rivers Mode.  Is it possible?

I've tried many different things including masking off the valley using a Distribution Shader, and still no substantial erosion happens in the valleys.

I want sediment to flow down the mountains, into a river, and out the side of the terrain.  Is it possible?

Is the only way to get rivers to use Rivers Mode (Rivers Tab)?  The example image i attached has exaggerated values to make the flat valley more pronounced.

Thanks,

Derek

WAS

#1
Valleys don't really have too much erosion, as they're flat valleys where the rivers carve through. But I imagine you can add extra low level displacement after the first erosion in your valleys, and do another erosion, with a much smaller scale, and less duration, probably masked to valley, but may add extra smaller erosion details to overall terrain if resolution is high.}

Also play with less rock hardness and downcutting.

WAS

Can also play with warping the smaller disp by larger terrain so it sorta follows features.

SuddenPlanet

Thanks WAS!  I'll see what I can figure out.  I want to push the Fluvial Erosion as far as I can before using the Rivers Mode.

The main hurdle I am dealing with is I am using DEM data that I have modified in World Machine which already has some nice river channels I don't want to loose, but those river channels are getting full of sediment and disappearing after doing the Classic Erosion.

I wish I knew how to adjust the settings so I can force all/most of the picked up sediment to continue down stream to the edges of the heightfield where I have a built in downslope which I created with an Edge Filter (GeoGlyph).

I saw your post here too, which may be a direction I can go:  https://planetside.co.uk/forums/index.php/topic,25926.0.html

OK, thanks again.

Derek

WAS

Can you get world machine to export a river map you can use to mask erosion so it doesn't erode the rivers? Or maybe trace it on a new layer in Affinity Photo or Photoshop with a soft brush that is wider than the river to create a soft river zone mask.

SuddenPlanet

#5
Quote from: WAS on December 22, 2021, 11:42:14 AMCan you get world machine to export a river map you can use to mask erosion so it doesn't erode the rivers? Or maybe trace it on a new layer in Affinity Photo or Photoshop with a soft brush that is wider than the river to create a soft river zone mask.

I am in the process of trying that and a few other things.  I'll post the results when I figure this out.

I wish there was a way to use Gaea, because there are so many more Erosion options and Sediment Removal is one of them.  I'm just waiting for full tiled builds to be supported so I can do 32k terrains (64 4096 tiles in 8x8 grid) which should be soon.

Derek

SuddenPlanet

Still working on this, but one thing I already figured out is higher resolution doesn't necessarily mean better results.

WAS

It really means smaller details sorts. 2-4k is good, and when I go higher it's usually on top of a 2-4k with a constant scalar mask as like 0.25 with feature scale of erosion smaller.

SuddenPlanet

Quote from: WAS on December 23, 2021, 01:44:37 AMIt really means smaller details sorts. 2-4k is good, and when I go higher it's usually on top of a 2-4k with a constant scalar mask as like 0.25 with feature scale of erosion smaller.

Do you have an example you can show me to see how you combine/blend the results of two classic erosion passes.  You mentioned using a "constant scalar mask".  I've never done that.  I always just used the Merge shader.

Dune

Wouldn't using a constant mask to decrease 'impact' be kind of similar to reducing erosion time/strength?

WAS

Quote from: Dune on December 29, 2021, 02:33:38 AMWouldn't using a constant mask to decrease 'impact' be kind of similar to reducing erosion time/strength?

Definitely not. It will compute the erosion different than just overlaying erosion less intensely.

WAS

#11
So, you actually did give me a great idea, Ulco. So thanks a lot for turning gears. It seems to me duration is what's really "carving" away the valleys, as it normally would in real world. So what if far less time passed, say 0.05, but the downcutting and such was super exaggerated? You'd get less valley, but more pronounced flows!

Check out the difference between default classic erosion settings, and my idea in application with less duration and exaggerated settings.\

PS if you think about it this approach makes sense for our area here in PNW. The mountains were carved out pretty recently during the ice age, and experience heavy rainfall and storms for exaggerated erosion, but less valleying in the actual alpine zone.


SuddenPlanet

Quote from: WAS on December 29, 2021, 03:53:33 PMlol

How did you give that the micro/macro look?  I see the image blurring out on the top and bottom.  Just curious if Terragen can render like that, or if you did it in Photoshop.

Your other examples above look promising.  I'll check out the scene.  I was using a duration of 0.1, so I'll try your 0.05 and see what it looks like.  Also I was setting Downcutting at 1.2 - 1.5 mostly.

WAS

I rendered out a custom depth pass with luminous shader, no sun, gisd, etc using distance shader from camera. Also the primary render was done with ambient occlusion with no atmosphere. Added chromatic abberation as often seen in those images when shot with another camera through a microscope viewing port.

PS depth pass was just used as a layer mask and normal lens blur in Photoshop.