Op 10/09/2023 om 18:01 schreef Bald Eagle:
> 
> With regard to TdG's interest in erosion, I was thinking about doing a quick
> test with an image map converted to a height_field.
> 
> The only problem here is that I don't recall if there was a way to edit the
> pixel data in the image_map, or in the height_field, or to somehow use a
> function {} or a 2D array to create an image or heightfield...
> 
> Or maybe a way to add/subtract / overlay onto the base image.
> I can't use arrays in functions, otherwise I could do image_map {function
> {array}}
> 
> It would be useful to not have to load an image, convert that to an array, use
> that array to create a mesh, then use the algorithm I'm experimenting with to
> edit the mesh.....
> 
> Does anyone have any ideas?
> 
> - BW
> 

Real Time is binding me hands and feet, so a belated comment so far.

What I am personally looking for / interested in is not so much the 
generation of natural-looking heightfields in terms of erosional 
patterns like mountains and valleys which is provided by e.g. World 
Machine. In itself it is an interesting topic and I remember (but cannot 
find again) a series of tests some years ago where the drainage patterns 
on in the heightfields were used to generate down-flowing rivers using a 
trace function. I must have a whole collection of examples somewhere 
under the dust but to date I have not been able to find those.

What I am /really/ interested in is the rockface erosion in cliffs and 
such which enhance the natural aspect of any mountain or landscape. As 
an example I attach a photograph of the Faroe Islands showing a cliff 
face, but what you can see are those (sub-)horizontal layers of more or 
less "competent" (= hard/soft) rocks, in the cliff and in the overlying 
landscape. They account for regions where the rock faces are more or 
less overhanging. This is impossible in classical heightfields but easy 
to achieve with isosurfaces of course.

Could we somehow achieve something similar using functions in POV-Ray, 
without the help of isosurfaces? That would be my question.

-- 
Thomas

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