Alain wrote:
> Can you flip it all over? Like put the scaner on top of the coin?

Or press the coin into some clay or plaster, then dribble some ink in
and let it dry?

-- 
  Darren New / San Diego, CA, USA (PST)
    The samba was clearly inspired
    by the margarita.

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Darren New <dne### [at] sanrrcom> wrote:

> Or press the coin into some clay or plaster, then dribble some ink in
> and let it dry?

Or wax... I like this idea. Another possibility is to do a "rubbing", using
carbon paper, or some modern equivalent, although the resolution will be
limited.

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Rick Measham <rickm*at%isite.net.au> wrote:
> > Rick Measham <rickm*at%isite.net.au> wrote:
> >>I'm not a real photographer, but I have food dye, a scanner and there's
> >>sure to be a dollar coin around here someplace.
>
> Found a coin, got the food-dye ready. Didn't work. First problem is that
> flatbed scanners still have an offset light and so the image is lit from
> one direction still.

Drats!

> Second problem is the coin traps air in the food-dye in the etching.

Double drats.
>
> I tried watering down the dye, and it worked a little better, but not much.
>
> The only thing I could think was to use deep enough mixture that the
> coin could be flipped around until there was no air pockets. However
> that would require some sort of glass container with a perfectly flat
> base.

That makes sense.

>I don't have one of those outside of povray!

:)

>
> If you've any more ideas, I'm happy to play!

Thanks for giving it a go. I've spent all weekend trying to improve the
milling. It's *so* hard to get it looking right.

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Here's a coin tower I did on the weekend, inspired by
http://fincher.org/Misc/Pennies/Sent.shtml

They're also fun to make with real coins. :)

I've now got better-looking milled edges than this pic shows, but I'm still
not happy with them yet. Also, I'm still playing with the pigment & finish.
I think I'll need to use a more complex pigment than the simple colour I'm
currently using.

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Attachments:
Download 'coinh4.jpg' (152 KB)

Preview of image 'coinh4.jpg'

Here's the best milled edge I can get; I've also rounded the edge and rims
slightly. I've smoothed the faces using water_level in the face
height_fields, but now the face details look like they've been stuck on. :(
 I shall work on improving this... maybe some mathematical trickery on the
source function for the heightfield will fix it.

The reflection still leaves a bit to be desired. I suppose I really need to
put the coins into a "richer" environment (pun inteded :). Radiosity &
photons will help, too, but those fancy milled edges really drag down the
rendering speed as it is.

Once everything's working to my satisfaction, I'll try to get all this stuff
into a form that's fit for public consumption. :) Anyone interested in some
general-purpose coin-minting macros?

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Attachments:
Download 'coink4.jpg' (134 KB)

Preview of image 'coink4.jpg'

PM 2Ring wrote:
> Here's the best milled edge I can get; I've also rounded the edge and rims

the milling is sweet, as are the rims.

> The reflection still leaves a bit to be desired. I suppose I really need to
> put the coins into a "richer" environment (pun inteded :). Radiosity &

i'm just looking at my coins sitting here in front of me, and 
they're all filthy, grungy. even the newer $2 ones are quite deeply 
lustrous. i don't know how you'd go about getting that sort of 
"depth" to the surface. but keep trying!

bob

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bob <bob### [at] mailcom> wrote:
> PM 2Ring wrote:
> > Here's the best milled edge I can get; I've also rounded the edge and rims
>
> the milling is sweet, as are the rims.

Thanks, Bob.

> > The reflection still leaves a bit to be desired. I suppose I really need to
> > put the coins into a "richer" environment (pun inteded :). Radiosity &
>
> i'm just looking at my coins sitting here in front of me, and
> they're all filthy, grungy. even the newer $2 ones are quite deeply
> lustrous. i don't know how you'd go about getting that sort of
> "depth" to the surface. but keep trying!

It's really hard to get them looking lustrous enough without being too
reflective. I'm currently playing with a texture_map that varies the
reflectivity etc and has some tiny normals to create a bit of reflection
blur,
but it really slows things right down, especially with high AA.

Here's one I did last night with moderate AA.

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Attachments:
Download 'coinn0.jpg' (74 KB)

Preview of image 'coinn0.jpg'

Nice work PM 2Ring.

However, to me, the overall contrast in this scene is to low. The
highlights (phong or specular) should be higher and the dark parts more
darker. I would try to lower the brightness of the coin color. Those are
my thoughts. I'm sure you have done many tests but I hope this may help.

Alberto.

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Alberto Mendoza <jac### [at] usbve> wrote:
> Nice work PM 2Ring.

Thanks, Alberto. Those coin images I rendered at home look too bright on my
machine here at work. The one below was done at work. I'm posting a .png,
because the JPEG has too many artifacts (and I don't have my usual image
processing software here).

> However, to me, the overall contrast in this scene is to low. The
> highlights (phong or specular) should be higher and the dark parts more
> darker. I would try to lower the brightness of the coin color. Those are
> my thoughts. I'm sure you have done many tests but I hope this may help.
>
> Alberto.

I trust you find the new image has much better contrast and highlights. :)

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Attachments:
Download 'coinq0.png' (490 KB)

Preview of image 'coinq0.png'