EnigmA Amiga Run 1998 July/EnigmA AMIGA RUN 29 (1998)(G.R. Edizioni)(IT)[!][issue 1998-07 & 08].iso/recent/iib122.lha/IIB/Threads/Make_Real_Gold

Internet Message Format | 1998-06-21 | 14KB

Date:         Thu, 28 May 1998 14:50:11 +0100
From:         George Cole <[e-mail]>
Subject:      [IML] QUEST: Realistic Gold

I'm trying to make realistic gold but I'm having problems. I've tried
using the Quick Attribute gold with a light clouds environment map. I
usually use this environment when making chrome-like textures but I
don't think it's quite right for gold. Here's the 9kb quick render:
http://freespace.virgin.net/cole.family/George/gallery/gold.jpg
The above image doesn't look too bad but when you see the full object it
looks totally unrealistic (also 9kb)
http://freespace.virgin.net/cole.family/George/gallery/gold2.jpg
I've tried all the different wrapping types (e.g. spherical, cylindrical
around Z and cylindrical around x) with this brush but the results are
practically identical.
Does any-one have a really good gold reflection map that I could use? Or
maybe tips on how to achieve realistic gold?
Thanks,

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Date:         Fri, 29 May 1998 19:53:32 +0100
From:         Richard Jennings <[e-mail]>

As a side issue to the gold attributes, there
are over 100 attributes files including some
gold ones at my web site, url below.

They are intended for use with IFW but should
work the Amiga (a texture path converter will be
required for some of them)

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Date:         Sat, 30 May 1998 01:02:43 +0800
From:         Kathryn Foston <[e-mail]>

Hi George

>I've tried all the different wrapping types (e.g. spherical, cylindrical
>around Z and cylindrical around x) with this brush but the results are
>practically identical.

changing the wrapping method of an environment map does nothing. It is
ALWAYS spherical.

>Does any-one have a really good gold reflection map that I could use? Or
>maybe tips on how to achieve realistic gold?
>Thanks,
>George Cole

Take a look at http://www.space.net.au/~transtech/images/gold1.jpg

This is a quick "gold" attribute I threw together with my usual techniques I
use for metals and other such surfaces..... I have never really tried to
make gold before, I've always used brass etc. I found it a bit difficult to
get it "different" from brass, without something gold and brass as a
real-life comparison in front of me. So this is just my "impression" of
gold.

If this is what you're looking for, I'll put up another tutorial, but one
secret is to find a suitable brush map. clouds may be ok for chrome, as
chrome is often seen outside, but gold is usually seen inside, so find an
indoor map as a reflection map, and try for indoor lighting.

Also, my tip I posted a while back about making spherical maps in PhotoShop
should be used on any reflection map, so that you don't get seams and
pinching in your environment ;)

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Date:         Thu, 28 May 1998 12:28:07 -0700
From:         Shawn Clabough <[e-mail]>

Working on making some gold object after looking at George's, I ran into this
interesting artifact (i.e. bug effect):

I was playing around with different primative shapes and decided to try a cone.

Here's how to recreate it:

In Detail editor -
Add a primative cone, default values.
Apply Metals.itx (Gold), default values.
Place an axis light source up to the right and in front of the object.
Quickrender trace and put c:\windows\clouds.bmp as the global brush and
backdrop picture.

You'll get an unexpected stepped reflection edge effect just like:
http://www.uidaho.edu/~shawnc/goldcone.jpg

p.s. George, I seemed to get a better reflection and specular highlight than you
did with using the default metals texture.  See
http://www.uidaho.edu/~shawnc/goldcone2.jpg

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Date:         Fri, 29 May 1998 18:49:14 +0100
From:         George Cole <[e-mail]>

Thanks for the help Shawn. I wasn't using metals.itx, just the Gold from
the Quick Attributes thing in Detail Editor.
Jeff, the top bit is supposed to be just coloured transparent perspex
like material, the bottom is supposed to be the gold. I know what you
mean about it looking like brass. I think half the problem is the
surroundings: a lake. Who knows what a big gold "golf-T" looks like in
the middle of a lake?? :o) I'll try your colour tips.
Katherine, an indoor environment map won't work as this model will be in
the middle of a lake. Your attributes look good though, could please
e-mail them to me privately?
Thanks to everyone who helped. I really want that fat gold ring look
with big wide reflections.

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Date:         Sat, 30 May 1998 13:45:44 +0200
From:         Conny Joensson <[e-mail]>

My attribute settings for gold:

Colour:    255 150 0
Specular:  255 245 180
Hardness:  25
Reflect:   180 160 125
Filter:    0 0 0
Shininess: 0
No Overdrive, IOR, Roughness, Brightness or Fog.

You'll *have* to use an environment map for this attribute to look ok. =
And depending on what that brushmap looks like you may have to fiddle =
with the Relect. Generally, the less contrasts in the brush, the higher =
the reflect value you need. At least for this attribute.

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Date:         Sat, 30 May 1998 16:23:05 -0400
From:         "Tim Wilson [Crestline]" <[e-mail]>

To George Cole re your message of Thu, 28 May 1998:

It sounds like someone may have found a nice solution to your gold problem
already, so this is probably academic at this point. But just so you know,
there is an inherent problem with simulating realistic gold in RGB
ray-tracers.

It is not possible to set up an object to reflect just the color _yellow_
when using ray-traced reflections. To create yellow in the RGB settings you
have to mix together red and green. Therefore, an object which is set to
reflect yellow will necessarily reflect both red and green as well,
destroying the illusion you're after.

In nature, metals reflect only certain wavelengths of light. In theory,
they could reflect only the yellow wavelength, and no red or green at all.
Gold isn't a pure yellow reflector. It reflects a number of different
wavelengths. But it does not reflect red or green as strongly as the RGB
color method would typically produce.

Environment mapping offers one way of dealing with this. However, you can
get a ray-trace to look more convincing if you're aware of this problem,
and use a good subtle mixture of red, green and even a bit of blue for the
reflective color, and surround the object with more muted, naturalistic
colors, rather than intense reds and greens.

There are of course other subtle things that could be done to improve the
realism as well, such as adding a little fresnel effect, and specular
flares, and so forth. But this color problem is probably the main issue.

A strong whitish specular highlight is probably a good idea as well.

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Date:         Thu, 28 May 1998 13:41:02 -0500
From:         Jeff Krase <[e-mail]>

Just a few comments...

>>> George Cole <[e-mail]> 05/28/98 08:50am >>>
>>http://freespace.virgin.net/cole.family/George/gallery/gold2.jpg

These are two different objects, right?  Is the top portion supposed to =
look like yellow glass or plastic? The bottom portion almost looks right, =
but not quite.  I think maybe a slight bump map or texture might help.  It =
almost looks more like brass than gold.  You might think about making more =
of a contrast between your specular highlights and the actual surface =
colour.

The surface colour should probably be a little darker and the specular =
highlights should be a little brighter -- maybe even closer to white than =
yellow.  I don't think the environment map is the problem here -- the =
surface attributes are not quite right.

If I can remember, I'll dig out the notes on making gold that came from =
that spiral book some of us bought from Impulse maybe three years =
ago...anyone remember that one?  Mike, do you still have copies of any of =
that material?

Hope this helps...

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Date:         Wed, 27 May 1998 22:18:12 -0500
From:         "Stephen G." <[e-mail]>

Check out this picture, it might have the kind of gold effect you are
looking for.

http://web2.airmail.net/sgiff/images/gam_off.jpg

or:

http://web2.airmail.net/sgiff/clock.htm

It's very simple to achieve this. So send me a note if you like it.

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Date:         Fri, 29 May 1998 10:39:36 CDT
From:         "Donald M. Rinderknecht" <[e-mail]>

"Stephen G." <[e-mail]> Wrote:
|
| It's very simple to achieve this. So send me a note if you
| like it.
|

Looks great, Stephen. Fill us in on the details!

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Date:         Fri, 29 May 1998 10:53:34 -0700
From:         Jan Brigham <[e-mail]>

Very nice gold, especially the first one. I think many on the list,
especially newbies would like the formula. Maybe you could post to the list.

Thanks,

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Date:         Fri, 29 May 1998 13:59:03 -0500
From:         Jeff Krase <[e-mail]>

Well, I'd like to see a tutorial.  Except for the glass and the black
background, I almost have trouble telling that the object was done on a
computer, rather than something taken out of a photograph.  I see what you
mean about it looking about like brass, too -- comparing the lantern with
my wedding ring, the lantern has a more greenish tint and the specular
highlights look a bit too "hot," but otherwise it looks very realistic and
almost like they were made from the same alloy. ;-)

One question I have -- is the environment map you used a photograph
or a render?

Eagerly awaiting your tutorial...

>>> Kathryn Foston <[e-mail]> 05/29/98 12:02pm >>>
Take a look at http://www.space.net.au/~transtech/images/gold1.jpg

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Date:         Sat, 30 May 1998 11:07:43 +0800
From:         Kathryn Foston <[e-mail]>

Hi Jeff

>Well, I'd like to see a tutorial.  Except for the glass and the black

Hmmm.. perhaps I shouldn't have put the overdrive up so much, but I liked
the effect...

>One question I have -- is the environment map you used a photograph
>or a render?

It's a render I did quite a while back, but it's been invaluable as an
environment map. I'd prefer to use a scanned photo, but don't have a
suitable one yet. What gave it away??

>
>Eagerly awaiting your tutorial...
>
it may be a few days........   ;)

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Date:         Sat, 30 May 1998 08:47:29 -0500
From:         Jeff Krase <[e-mail]>

Heya, Kathryn.

>>> Kathryn Foston <[e-mail]> 05/29/98 10:07pm >>>
>Hmmm.. perhaps I shouldn't have put the overdrive up so much, but I
>liked the effect...

I like it too, but it takes away from the realistic gold look and makes it
look more like brass or another alloy.

>It's a render I did quite a while back, but it's been invaluable as an
>environment map. I'd prefer to use a scanned photo, but don't have a
>suitable one yet. What gave it away??

Since you asked... ;-)

Something looks a little off about the lighting.  In a photo, there'd be
more bounce light and colour.  Also, the wood looks rendered.  Also, I
might suggest that the lighting in the environment map seems to either be
coming from the other direction or it isn't affecting the chair-type
object as it should.  If the light is really coming from the other
direction, I'd suggest re-arranging the lighting in your lantern scene so
that it comes from the same direction as your environment map. ;-)

Also, did you use some implementation of the Fakely texture on the
lantern?  There's something about the edges of the lantern that looks more
CG than the front of it.

>it may be a few days........   ;)

Care to share your attribute settings with the list in the meantime, then?
8-)

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Date:         Sat, 30 May 1998 22:02:52 +0800
From:         Kathryn Foston <[e-mail]>

I'm suprised you could pic out the wood so clearly from just the
reflections. It was just a quickrender from the detail editor, and wasn't
meant to be a complete scene, just an example of the gold attributes I came
up with.

If you want to see the pic I actually used, it's in my gallery under
"projects under construction". it's the one of the room

>Also, did you use some implementation of the Fakely texture on the lantern?
There's something about the edges of the lantern that looks more CG than the
front of it.

Gee you're quick ;) Although I don't think it's much of a secret that
Abfakley is my favourite texture .

Well.... I'm working on the tutorial, but if you're interested, I used:

fracbump
ABfakely (x2)
ABfakeNC
ABcolorheight (x3)
AAnoise
Environment map

Hope that keeps you going till then ;)

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Date:         Sun, 31 May 1998 00:09:42 +0800
From:         Kathryn Foston <[e-mail]>

Ok, I've finished the gold tutorial, although it was a bit rushed. I hope
there's no stupid errors. It's at:

http://www.space.net.au/~transtech/goldifw.htm

Enjoy

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Date:         Sat, 30 May 1998 14:41:14 -0700
From:         Charles Patterson <[e-mail]>

Nice tute, thanks.  Could you show the image you created for the map
also?

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Date:         Sun, 31 May 1998 08:41:39 EDT
From:         Phil Cook <[e-mail]>

Kathyrn,

Very nice "gold" tutorial--simple, well illustrated and easily understood.

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Date:         Sun, 31 May 1998 19:10:56 -0700
From:         Jan Brigham <[e-mail]>

Thank you Kathryn. I found the tutorial very easy to follow & for the first
time have a concept of how to use these textures together. I plan on buying
the Esscence textures when I have some money. I just upgraded my computer.
In all the tutorials I have checked out, this is a first of its kind.
Exellent work as usual.

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