"Kirk Andrews" <kir### [at] tektonartcom> wrote in message 
news:web.494144ad151cbdc1da29fa390@news.povray.org...
> I've got a paper due, so once again I am POV-ing.
>
> I'm trying to calculate the flow of water across a terrain, so that hopefully 
> I
> could eventually add realistic rivers, gullies, and ponds to a terrain.  It
> ought to be possible to feed the water flow information back into the function
> used to create the terrain itself, to create erosion.
>
> So far, my code simply picks a random starting point, checks the altitude of
> points around it, and chooses the lowest point. Then it repeats, creating 
> cones
> to indicate its path.
>
> When the lowest new point is higher than the current point, water ought to
> collect.  I've tried adding code to create ponds where the water ought to
> collect, but I'm running into weird problems.
>
> I'm posting in the hopes that perhaps some of the brilliant minds around here
> could improve upon what I'm doing.  In fact, I'd be surprised if no one around
> here has tried this before, but I couldn't find anything like it yet.
>

After reading this thread so far, there is one element that is missing and
might lead to a different approach.

Water flow and accumulation and erosion depends more on ground
composition than anything else.
At high altitudes it is likely you have hard rock surfaces that result in
movements of thin sheets of water.
If you think about it, the lower you go in altitude the 'softer' the material is
and thus the greater effect water has on surface deformation.
The volume of colected and moving water will channel through a
linked chain of soft areas. Soft areas will grow with time.
(movable debris goes downhill.)
Also- water falls on surfaces not at discrete target points, but as a
general area effect. Accumulation is a differential process that
changes at particular points depending on what the nearest neighboring
points are doing.

So - what to do? Add an array (or other data keeper) that tracks the
relative 'softness' of a determined delta of surface.
Assume something about average rainfall/snowfall, temperatures and
whatever else seems pertinent.
Search for points or areas that are the softest at the highest altitude
and calcualte average accumulation based on slope, etc.
Once you have these starting points your pump, so to speak, is
primed and then you can make subsequent passes over your data to
simulate a dynamic re-distribution of water stores.
(the array of point softness will change with time)

Detailed granularity of your analysis will make for a better simulation
and might make the actual cranking out of implementation code
easier as you will not box yourself into so many untenable concepts.

Oh - yeah - springs will be a whole different layer of complexity you
might add. Water seeps down into underground spaces and follows
its own unseen path to 'spring' out at locations that might never see
rainfall or might seem to defy local topology.

Go for it - I don't think you can ever get to a final, all encompassing,
method, but the journey should be fun.

Hope some of this sparks your imagination.

Post a reply to this message