have you seen any of the tutorials and utilities made for positioning
items on a height field?  i think there is something out there that can
define areas of height fields to be worked on.  i think it is genesis
toolkit found at www.rhein-ruhr.de/~schrammel/index.htm.  i'm not sure
it's usefull, but there you go.

Christoph Hormann wrote:
> 
> ryan constantine wrote:
> >
> > i think it depends on whether it is wind erosion or water erosion.  wind
> > rounds, water peaks.
> >
> 
> IMO this type of erosion is mainly caused by the changing temperatures
> destroying the structure of the material at the surface.  Of course water and
> wind are major factors for transportation of material.
> 
> > if you could define areas most and least likely to erode, that would be
> > cool.  for example, areas with a lot of ground cover don't erode as fast
> > as open areas.  dirt erodes faster than rock, etc.
> 
> That's a good idea, it is only a problem how to define those areas.
> 
> BTW, my code partly already does this, because it erodes more on steeper areas,
> where there is normally fewer vegetation.
> 
> Christoph
> 
> --
> Christoph Hormann <chr### [at] gmxde>
> Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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> That's a good idea, it is only a problem how to define those areas.

Could you perhaps allow the user to provide an erosion_map for it?

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Christoph Hormann wrote:
> 
> Just made some tests with an Erosion routine I programmed some time ago.  The
> result has some similarity with ridged multifractal but it is an editing
> function modifying any existing heightfield.
> ...

Interesting.

Is it a POV-script doing this ?

And if so, then how is it done ?


Tor Olav
--
mailto:tor### [at] hotmailcom
http://www.crosswinds.net/~tok/tokrays.html

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Maybe an animation would help illustrate your technique? (O.k., so I just
like animations a lot... :)

Regards,
Dave

"Christoph Hormann" <Chr### [at] schunteretctu-bsde> wrote in
message news:396A0D1D.2B382007@schunter.etc.tu-bs.de...
>
> Just made some tests with an Erosion routine I programmed some time ago.
The
> result has some similarity with ridged multifractal but it is an editing
> function modifying any existing heightfield.
>
> And it is quite fast (about 800 milliseconds for a single run on a 256x256
> point heightfield on my K6/500)
>
> The first one is the starting heightfield, the second one after about 15
runs
> with smoothing between, the third after 15 additional runs.
>
> Please tell me what you think of it, I wonder if anybody has done
something
> similar before.
>
> I am already planning some addition to stop erosion process, when a
certain
> slope is reached, which would be more realistic.
>
> Christoph
>
> --
> Christoph Hormann <chr### [at] gmxde>
> Homepage: http://www.schunter.etc.tu-bs.de/~chris/


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Christoph Hormann wrote in message
<396A32E4.CF4A5F18@schunter.etc.tu-bs.de>...
>That's a good idea, it is only a problem how to define those areas.


Allow a user to provide a second greyscale image that specifies the
"hardness" of parts of the map.

Mark

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Andrea Ryan wrote in message <396A333F.8A101D00@global2000.net>...
>Can a routine be made to do wind erosion?  Desert landscapes could be made
with
>these mushroom shaped rocks that get eroded more at the bottom.  However,
I'm not
>sure if that can be done with height fields.
>Brendan


It can't be done with a heightfield, but a .df3-based isosurface would work
quite well for this.

Mark

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Dave Blandston wrote:
> 
> Maybe an animation would help illustrate your technique? (O.k., so I just
> like animations a lot... :)
> 
> Regards,
> Dave
> 

Never did an animation before :-) so i will have to learn it first...
NTL, it is a good idea.

Christoph

--
Christoph Hormann <chr### [at] gmxde>
Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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Tor Olav Kristensen wrote:
> 
[...]
> 
> Interesting.
> 
> Is it a POV-script doing this ?
> 
> And if so, then how is it done ?
> 
> Tor Olav

No, it's a delphi program.

BTW, that leads to an interesting idea for a new feature:

   height_field {
      pov {
         "hf.pov" 
         width=512
         height=512 
      }
   }

   or similar...

Recursive implementation could occupy povray forever :-)

Christoph

--
Christoph Hormann <chr### [at] gmxde>
Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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Mark Wagner wrote:
> 
[...]
> 
> Allow a user to provide a second greyscale image that specifies the
> "hardness" of parts of the map.
> 
> Mark

That's already planned (it's already possible to specify a B/W mask for total
exclusion of certain areas).  

The problem is how to generate that map, because in real world the amount of
erosion is influenced by a lot of factors like:

   -rock material
   -water amount
   -slope
   -hillside orientation
   -most often wind directions
   -existing vegetation
   -...

Some of these factors can be calculated from the heightfield, some have to be
specified by the user, but for example not every user drawn "geological map" is
possible, it is not reasonable if the material changes from granite to sand just
at the top of a mountain.

Christoph

--
Christoph Hormann <chr### [at] gmxde>
Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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That's what I said.

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