Braided river, streams ?

gnoop

Does anyone knows a terrain tools or just a simple way to generate them ?  Looking physically accurate more or less?   So far whatever terrain generator I tried  , Gaea and such are only capable to do  roots like  looking  errosion while I need more like a dried  river bad  with intertwined streams.    

Generative AI seems useless for the task.  SDesigner I used before  for this  still looks like hand maid, fancy of a sort .  You instantly feel an artificial nature , not true physics driven.      I ended up just drawing it by hand before feeding it to Designer for slope blur but wonder is there a true way by simulation somewhere?   I see lots of nice braided  things in movies  for example.  How do they do it?

Eric Chadwick

Unreal makes it pretty easy
https://dev.epicgames.com/documentation/en-us/unreal-engine/water-body-actors-in-unreal-engine

I've manually created lava streams that branch and reconnect, just using extruded splines, one for each branch. Then welding the sides together where they meet side-by-side to make the main stream. The UVs are in strips, and I adjusted the UVs so they're side--by-side seamless where the branches join together. Then it's just vertex colors to blend the textures together.

gnoop

Thanks for the idea  Eric Chadwick.      But I meant something  more like this 

But already dried out , without water.  A desert version. 

Google suggests  Delft3d  open source software you have to compile on your own.   Anyone tried what it is?     I am tired of trying to make SDesigner do it  believably.  Ironically I used some ancient  Geocontrol  soft , a predecessor of world creator  . They have some "river" tool  that did something like that  after long  voodoo and dancing   around it.  Can't even make it work now.  

https://www.shutterstock.com/shutterstock/videos/3926639295/preview/stock-footage-aerial-view-of-braided-river-and-mountains-in-summer-in-iceland-hyperlapse.webm

a better example probably  but i need it in smaller scale .  I am alredy wasted days  trying to both Designer and vector soft   to draw curves  manually  and feel it might took me a month more to have something procedural  for easy variations .

Eric Chadwick

Ah. Sounds like a job for Houdini, e.g. https://www.artstation.com/artwork/GoVK1

gnoop

Thanks Eric

Eric Chadwick

World Machine has a river device, with floodplain and meander controls. 
https://help.world-machine.com/topic/device-river/ 

Those two words could also help with your searches: floodplain, meander.

gnoop

cool, thanks Eric .  Now I need to find my ancient  world machine license . Is it something new  and fresh  or been there all the time?     I recall some river tool there but  don't remember it could do braids .  

found one more cool picture :  

ps  A best way to do it is probably a long bendy sobol brush over a polished , oil smeared canvas  .  But it would takes hours for every new variation .  Does anyone know an AI that could draw it believably  without fancy looking  random weird zig-zagz?  

I recall the times when we used white plastic sheets  and coffee splashes    as well as real brush  painting  to make texture masks . Those old days .  It's all now so much long  forgotten.      Does anyone  have an idea how  to do it quickly old "real thing" way  on a plastic sheet?   Some mix of oil and watercolor + ox gall maybe ?

Klunk

isn't it just a scrawny stretched out 3d tree projected onto a 2d plane ?

Eric Chadwick

Yeah maybe just a bunch of splines, with a different noise seed each, and various thicknesses.

Turn that into a texture, and use it to control the placement of rocks and sticks.

gnoop

Yeah,  maybe .   I am trying to use geometry nodes to make  something procedural . The issue is  you instantly see it's not true since real thing is driven by some hydrodynamic forces , deeper down where the stream is speedier , branching not by just random places . IMO you instantly feel it subconsciously when you look to real thing vs  that  2d tree projection or bending just by random point shift . 

Eric Chadwick

Yeah I guess it would need a bit of finesse, regardless. But here's a quickie with 3ds Max, changing the Seed on the Noise modifier.

Benjammin

gnoop said:

Yeah,  maybe .   I am trying to use geometry nodes to make  something procedural . The issue is  you instantly see it's not true since real thing is driven by some hydrodynamic forces , deeper down where the stream is speedier , branching not by just random places . IMO you instantly feel it subconsciously when you look to real thing vs  that  2d tree projection or bending just by random point shift . 

Seems like you might need a system that feeds back into and deforms the landscape so your random branching feels deterministic?

gnoop

Eric Chadwick said:

Yeah I guess it would need a bit of finesse, regardless. But here's a quickie with 3ds Max, changing the Seed on the Noise modifier.

That looks nice indeed  and I did something like that in Blender Geometry nodes too by roughly same stack   but  isn't it instantly obvious the thing is not real and have a typical  "procedural" taste  just because a  half of child streams are crossing each other  and not  do typical flow in  before a bend  and out after , a core character feature of real braided  streams.   Besides   it represents only river surface  and I need  a depth map for dried stream , sort of desert version.   something like this  but with more pronounced main/central  stream: 

Notice , there is no  child stream just crossing each other  and a lots of depth variety in specific places .   When a stray stream is back in the depth is pretty shallow  etc.   It's  not really that simple as just a random noise shift  IMO.      Should be a  simulation  probably. 

Eric Chadwick

Hmm. One thing you could try is making a flat slope, displacing it with noise, then tell World Machine (or whatever fluid solver) to send water down it. Should end up with something similar. 

gnoop

I  tried Gaea , It only makes root like  branches , never intertwined . I think world machine does the same.    

Noren

Have you tried letting it run from opposite directions (one after the other) or maybe overlay two displacements? In a min/max way. The pattern in some of your references doesn't look overly dependent on being up- or downstream, so if you find some settings with less branching, you could mix two central ones for the main pattern and a broader one for some tributaries to get better angles for those.

poopipe

This can't really be done without an evolutionary algorithm of some kind - at least not in a way that gives you branching and some sort of physical plausibility. 

It's not practical to implement that sort of algorithm in designer (it is possible)  because each growth step must feed off the previous growth step and the only way to pass that around in designer is to manually chain nodes together (or script your graph creation)  it's fine if you only need a few generations but you're looking at tens of thousands to simulate this.

I'm not entirely clear on what options are available in Blender but you could probably simulate this quite effectively with a particle system and a few repellers to emulate harder ground material - that's basically how these things form in real life. 



 

gnoop

thanks for your opinion poopipe.    So far looks like  centuries old technique  painting it by hand  by long flat  sabel brush by very oily paint with random rotation,   then using another puffy sable brush to subtly smear the paint tangential to original stroke   makes a best illusion for height image.      Too bad there is nothing like old Creative House  Expression anymore  where you could do 10 randomly  alternating non square   parts  and draw them  by vector spline perfectly bending and scaling .  Nothing like what Designer curves do.    How such a great soft could die is beyond my understanding.