Here's my try at rendering Mr. Dahlstrom's crater function which uses a
spline. I haven't changed anything about it yet except to apply a psuedo
curved surface over the whole thing so I could get a asteroid look instead
of flat plane. This is only a heightfield but the crater function has a
sphere added to make the image used for the HF. I really like these craters
so thanks, Johannes, from me too.

Just a thought here, you (anybody) might want to add your name and possibly
e-mail to your scripts before posting them. I had already forgotten who made
it so I looked it up again and added your name to my file here. I don't
always do that either though, depends on whether I'm thinking of it at the
time or not.

--
Farewell,
Bob

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impressive!

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hughes, b. wrote:

> Here's my try at rendering Mr. Dahlstrom's crater function which uses a
> spline. I haven't changed anything about it yet except to apply a psuedo
> curved surface over the whole thing so I could get a asteroid look instead
> of flat plane. This is only a heightfield but the crater function has a
> sphere added to make the image used for the HF. I really like these
> craters so thanks, Johannes, from me too.

"Dahlstrom Craters" - now that sounds cool ;) I'm glad to hear you like it. 
And, your image is very impressive.

> Just a thought here, you (anybody) might want to add your name and
> possibly e-mail to your scripts before posting them.

Ok, a good idea. Will do in future.


> 
> --
> Farewell,
> Bob

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Impressive yes!
Eeeeeeerrrrr where did I put the keys of my LEM?
Marc

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Thanks all. Here's one with higher-res, some turbulence in the pattern and a
slightly different spline. Probably the first time I've been able to render
craters that looked like craters so this is great.

I ended up passing over Dave Blandston's cratered terrain (Fun with
height_fields 10/25/2002) which I had seen recently but that looked real
good too. Just grabbed it up to try also.

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Looks good, I like the name "Dahlstrom crater". ;-)

Here's some real crater pictures:
http://antwrp.gsfc.nasa.gov/apod/ap990326.html
http://antwrp.gsfc.nasa.gov/apod/ap020913.html
http://antwrp.gsfc.nasa.gov/apod/ap010809.html
http://antwrp.gsfc.nasa.gov/apod/ap011215.html
http://antwrp.gsfc.nasa.gov/apod/ap020322.html

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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"Christopher James Huff" <chr### [at] maccom> wrote in message
news:chr### [at] netplexaussieorg...
>
> Here's some real crater pictures:
> http://antwrp.gsfc.nasa.gov/apod/ap990326.html
> http://antwrp.gsfc.nasa.gov/apod/ap020913.html
> http://antwrp.gsfc.nasa.gov/apod/ap010809.html
> http://antwrp.gsfc.nasa.gov/apod/ap011215.html
> http://antwrp.gsfc.nasa.gov/apod/ap020322.html

Which goes to show why I can only attempt the artistic approach and not hope
to achieve the reality of nature  :-)

Anyway, I submit this latest rendering. Been trying to get better craters
and add rills and more color. I'm at a loss so far to have the craters
overlap in a way that shows proper age. They are still additive or averaged
and aside from making separate areas of different levels of cratering I
haven't happened across the right method yet.

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It looks great! The overlapping craters are problematic, but apart from that
(if you don't mind that I nitpick) I think the craters all have a too
uniform torus, so they tend to look like ripples in water. To expand the
formulas with more stuff, I've noticed on Chris's links that some craters
leave traces around them, sort of ... dust tales in all directions.

Nevertheless these two images are impressing; this one, and the ~230kb
version (can't decide which one is best).

Regards,
Hugo

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In article <3dcbd2b8@news.povray.org>, "Hugo" <hua### [at] post3teledk> 
wrote:

> It looks great! The overlapping craters are problematic, but apart from that
> (if you don't mind that I nitpick) I think the craters all have a too
> uniform torus, so they tend to look like ripples in water. To expand the
> formulas with more stuff, I've noticed on Chris's links that some craters
> leave traces around them, sort of ... dust tales in all directions.

The radial spokes? That is an interesting effect...you would have to 
combine a function texture with the geometry (if this isn't already 
done).

One thing I noticed: the craters overlap each other. In reality, new 
craters tend to obliterate the features where they hit, and maybe spread 
debris over parts of surrounding craters...you would see traces of large 
old craters covered by small new ones, or a big new one with only a few 
small marks on it. I don't know how this would be done with a function, 
I'd do it by simulating the craters hitting over time on a mesh 
landscape.

Still, it looks like a very good "cratered landscape", the vast majority 
of people wouldn't notice this or care.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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"Christopher James Huff" <chr### [at] maccom> wrote in message
news:chr### [at] netplexaussieorg...
>
> The radial spokes? That is an interesting effect...you would have to
> combine a function texture with the geometry (if this isn't already
> done).

Already been thinking that over, not sure I could do it right enough.

> One thing I noticed: the craters overlap each other. In reality, new
> craters tend to obliterate the features where they hit, and maybe spread
> debris over parts of surrounding craters...you would see traces of large
> old craters covered by small new ones, or a big new one with only a few
> small marks on it. I don't know how this would be done with a function,
> I'd do it by simulating the craters hitting over time on a mesh
> landscape.

Not me, I couldn't use a mesh easily enough.  ;-)

> Still, it looks like a very good "cratered landscape", the vast majority
> of people wouldn't notice this or care.

Thanks again. Yeah, I believe most people would see this kind of thing in a
imaginitive sort of way rather than from well-known memory. Same thing as
how any Earth-bound ground might be a real place or imagined. Variation
seems the key though.

As the new subject line is saying, I've attached a redo of Dave Blandston's
craters and those show a kind of ejecta around them, but I haven't changed
that much from the original.

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