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Thomas de Groot <tho### [at] degroot org> wrote:
> In this particular example, the erosional process seems to have been
> better. A pity I cannot reproduce exactly what I did to get there as I
> was just messing around without paying to close attention to the
> different steps.
>
> --
> Thomas
That's looking really good, Thomas!
Which software are you using for erosion? Now that I don't have a PC anymore,
I've got to find something to run on my Mac.
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On 2/17/2017 1:29 PM, Kirk Andrews wrote:
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> In this particular example, the erosional process seems to have been
>> better. A pity I cannot reproduce exactly what I did to get there as I
>> was just messing around without paying to close attention to the
>> different steps.
>>
>> --
>> Thomas
>
> That's looking really good, Thomas!
>
It does indeed. :-)
> Which software are you using for erosion? Now that I don't have a PC anymore,
> I've got to find something to run on my Mac.
>
FYI
Thomas is a PC user.
I am trying to replicate it in Blender as a goal in learning to use
Blender. If I get anywhere I will post it here. But there is a lot to
learn, an awful lot. :)
--
Regards
Stephen
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Thomas de Groot <tho### [at] degrootorg> wrote:
> On 16-2-2017 19:59, Kirk Andrews wrote:
> > So, I'm starting to get my head around what's happening with the lakes not
> > filling up. As it searches for a point lower than the water level in an
> > increasing radius, it doesn't take into account whether or not the water can
> > actually flow that way.
> >
> > So, for example, maybe the lake extends away to the north, beyond the current
> > testing radius, and there is a ridge to south, but then a lower point. Since the
> > lake extends away to the north, the algorithm detects that as the lowest point
> > (equal to the current water level), and therefore does not raise the water
> > level, but does keep expanding the radius. Eventually, it does detect a lower
> > point, but it's on the other side of the ridge. Right now, the algorithm has no
> > method to detect that the water can't get there from here, so it goes ahead and
> > jumps the stream through the rock to the other side.
> >
> >
>
> Ah. That is a complication indeed.
>
> --
> Thomas
To do this *right*, I'm thinking you'd have to do a full-blown physics
simulation. But, I'm wondering if we can't get to a reasonable approximation
with some extra trace checks. Right now, it's only checking straight down from
above, but if we also checked across from the center point, maybe we could
eliminate points that didn't have a straight path from here to there. I
experimented with that idea some but I can't tell if it's really working yet.
https://www.dropbox.com/s/49nmnd5z1kzhms0/Water4.pov?dl=0
Post a reply to this message
Attachments:
Download 'water4.png' (1993 KB)
Preview of image 'water4.png'
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Stephen <mca### [at] aolcom> wrote:
> > Which software are you using for erosion? Now that I don't have a PC anymore,
> > I've got to find something to run on my Mac.
> >
>
> FYI
> Thomas is a PC user.
>
Oh, I'm sure; but some of them are available on both platforms. I used to use
WorldMachine, but it's PC only.
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Not sure if this helps any - might be useful as a lead...
Busy at work, but couldn't help peeking
http://ncsu-geoforall-lab.github.io/geospatial-modeling-course/grass/simwe.html
http://www4.ncsu.edu/~hmitaso/gmslab/irwin/irwin1.html
https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=simwe+model
http://geoinfo.amu.edu.pl/sgp/LA/LA17/LA17_081-086.pdf
http://tucson.ars.ag.gov/isco/isco10/SustainingTheGlobalFarm/P081-Mitasova.pdf
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"Bald Eagle" <cre### [at] netscapenet> wrote:
> Not sure if this helps any - might be useful as a lead...
> Busy at work, but couldn't help peeking
>
> http://ncsu-geoforall-lab.github.io/geospatial-modeling-course/grass/simwe.html
>
> http://www4.ncsu.edu/~hmitaso/gmslab/irwin/irwin1.html
>
>
https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=simwe+model
>
> http://geoinfo.amu.edu.pl/sgp/LA/LA17/LA17_081-086.pdf
>
> http://tucson.ars.ag.gov/isco/isco10/SustainingTheGlobalFarm/P081-Mitasova.pdf
Oh man, looks like I've got reading to do.
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> To do this *right*, I'm thinking you'd have to do a full-blown physics
> simulation. But, I'm wondering if we can't get to a reasonable approximation
> with some extra trace checks. Right now, it's only checking straight down from
> above, but if we also checked across from the center point, maybe we could
> eliminate points that didn't have a straight path from here to there. I
> experimented with that idea some but I can't tell if it's really working yet.
>
Or, I suppose it could be as simple as what paint programs do with the fill
tool, and treat it more like square pixels.
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"Kirk Andrews" <kir### [at] tektonartcom> wrote:
> To do this *right*, I'm thinking you'd have to do a full-blown physics
> simulation.
Hey Kirk,
I'm not sure if this is helpful or not, but if your computer has a GPU
supporting pixel shaders, check out this one I posted a while back:
https://www.shadertoy.com/view/XsKGWG
It approximates hydraulic erosion on a height map, using a sort of basin-filling
method as a key part of the process. It won't form rivers on flat plains, since
momentum isn't taken into account (would need to probably implement
Navier-Stokes equations for that, which would be difficult using Shadertoy since
a fluid sim needs to iterate over a certain operation some 30-50 times per
frame, to the same texture). Also, the lakes seem to be slightly sloped.
Sam
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"Samuel B." <stb### [at] hotmailcom> wrote:
> "Kirk Andrews" <kir### [at] tektonartcom> wrote:
> > To do this *right*, I'm thinking you'd have to do a full-blown physics
> > simulation.
>
> Hey Kirk,
>
> I'm not sure if this is helpful or not, but if your computer has a GPU
> supporting pixel shaders, check out this one I posted a while back:
> https://www.shadertoy.com/view/XsKGWG
>
> It approximates hydraulic erosion on a height map, using a sort of basin-filling
> method as a key part of the process. It won't form rivers on flat plains, since
> momentum isn't taken into account (would need to probably implement
> Navier-Stokes equations for that, which would be difficult using Shadertoy since
> a fluid sim needs to iterate over a certain operation some 30-50 times per
> frame, to the same texture). Also, the lakes seem to be slightly sloped.
>
> Sam
Wow! I'd never heard of Shadertoy. Is it possible to download the resulting
height map?
Post a reply to this message
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"Kirk Andrews" <kir### [at] tektonartcom> wrote:
> "Samuel B." <stb### [at] hotmailcom> wrote:
> > "Kirk Andrews" <kir### [at] tektonartcom> wrote:
> > > To do this *right*, I'm thinking you'd have to do a full-blown physics
> > > simulation.
> >
> > Hey Kirk,
> >
> > I'm not sure if this is helpful or not, but if your computer has a GPU
> > supporting pixel shaders, check out this one I posted a while back:
> > https://www.shadertoy.com/view/XsKGWG
> >
> > It approximates hydraulic erosion on a height map, using a sort of basin-filling
> > method as a key part of the process. It won't form rivers on flat plains, since
> > momentum isn't taken into account (would need to probably implement
> > Navier-Stokes equations for that, which would be difficult using Shadertoy since
> > a fluid sim needs to iterate over a certain operation some 30-50 times per
> > frame, to the same texture). Also, the lakes seem to be slightly sloped.
> >
> > Sam
>
> Wow! I'd never heard of Shadertoy. Is it possible to download the resulting
> height map?
It's possible, but will require editing the source code of the Image shader to
have it display only the height map (or water map, or both [hint: the landMap()
and waterMap() functions give this data]). You can then (in Firefox) right click
on the display window and choose Save Image As... Unfortunately this will only
get you an 8 bit image. For 16 bit data, you'll need to convert it over to the
red/green format (which POV-Ray supports) and then save. (For all I know saving
16 bit data from Shadertoy might be possible if you know Java.)
Better yet is to get your own shader program up-and-running using SFML or the
like. (Although the last I heard SFML would only support 8 bit textures, the
devs assuming anything else was unnecessary :P I was able to add 16 bit texture
support myself, but who knows how many versions ago that has been...)
Sam
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