Dan Connelly wrote:
> 
> I had no problem seeing features.... but I suggest
> the following changes :
> 
> 1. The map field is defined from y=0 to y=1.  You want
>    y=-1 to y=+1.  Therefore you need to apply a translation
>    and a scale.

oh, I didn't seem to notice that. The bumpmaps are pretty 
ragged, so I didn't notice. Thanks.

> 2. specify a finish.

I found that 
finish {
        	ambient .15
		diffuse .5
		phong .07
	}

works pretty well.

> 3. Your filename is different than the one you posted (jbrp.0.pgm).
>    This may be an issue.

you know, I was so excited to be posting the a newsgroup for the
first time in years I wasn't paying any attention. Sorry :-)

> 4. "interpolate 2" should almost always be used with bump maps
>    to prevent pixellization artifacts.

I didn't seem to notice a lot of difference between interpolate 2
and interpolate 4, but I did notice the difference between 0 an {2,4}.

> 
> Consider the following scene :

hrm...lemme quickly render and see...

wow, I commented out the translation line and I quickly
see what you mean about the map location! I didn't notice it
in mine because I rotated them about 45deg. 

Now why did I put a "phong" shading in mine when I 
should have been using "specular"...Hrm. It sharpens it quite
a bit. I like the effect when roughness in increased as well.


> http://www.flash.net/~djconnel/

-- 
# Jed Reynolds, mailto:jed### [at] surfsoftcom http://www.surfsoft.com/~jed
# "...I've seen the old geeks talk to the young geeks, and they speak
# the same language. There's no age gap or anything." --Steve Wozniak

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Jed Reynolds wrote:
> > 4. "interpolate 2" should almost always be used with bump maps
> >    to prevent pixellization artifacts.
> 
> I didn't seem to notice a lot of difference between interpolate 2
> and interpolate 4, but I did notice the difference between 0 an {2,4}.

Bilinear interpolation is a pretty standard scheme, so I always
use it... I haven't investigated normalized distance, so can't
comment on the speed/quality tradeoffs.


> >
> > Consider the following scene :
> Now why did I put a "phong" shading in mine when I
> should have been using "specular"...Hrm. It sharpens it quite
> a bit. I like the effect when roughness in increased as well.


Don't take my choice too seriously..... some folks use Phong
and others specular.  I choose the former because the docs
claim it is more realistic, but I can't claim this is an
otherwise educated preference.

Anyone care to comment?

Dan

-- 
http://www.flash.net/~djconnel/

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I posted a couple of nice pictures about my planets and
a brief explanation of how I made them.


http://www.scruz.net/~hed/pub/pov_planets/

pretty fun for a weekend render session, I'd say.

--jed

-- 
# Jed Reynolds, mailto:jed### [at] surfsoftcom http://www.surfsoft.com/~jed
# "...I've seen the old geeks talk to the young geeks, and they speak
# the same language. There's no age gap or anything." --Steve Wozniak

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Dan Connelly wrote:

> > > Consider the following scene :
> > Now why did I put a "phong" shading in mine when I
> > should have been using "specular"...Hrm. It sharpens it quite
> > a bit. I like the effect when roughness in increased as well.
>
> Don't take my choice too seriously..... some folks use Phong
> and others specular.  I choose the former because the docs
> claim it is more realistic, but I can't claim this is an
> otherwise educated preference.
>
> Anyone care to comment?
>
> Dan

I generaly will use specular over phong in my scenes too.
Phong seems to me to make the highlights too large.
There are exeptions to this, of course, but it takes experimentaion
to decide when one is better than the other.

Ken

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Ken wrote:
> 
> Dan Connelly wrote:

> > Don't take my choice too seriously..... some folks use Phong
> > and others specular.  I choose the former because the docs
> > claim it is more realistic, but I can't claim this is an
> > otherwise educated preference.
> 
> I generaly will use specular over phong in my scenes too.
> Phong seems to me to make the highlights too large.
> There are exeptions to this, of course, but it takes experimentaion
> to decide when one is better than the other.

Whoops!  Ken fortunately saw through my typo.  I should
have said I choose the "latter" (ie specular).

-- 
http://www.flash.net/~djconnel/

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'phong' hilights have color based upon lights, whereas 'specular' is white 
regardless of colors used in lights.
Though they say specular is more "realistic" you wouldn't think so would you? 
Since any hilight ought to show a light sources color;
perhaps the pigment and light colors don't blend realisticly, but I don't have 
proof of this.

Message <360E9FEA.CB3A7D81@flash.net>, Dan Connelly  typed...
> some folks use Phong
>and others specular.  I choose the former because the docs
>claim it is more realistic, but I can't claim this is an
>otherwise educated preference.
>
>Anyone care to comment?
>
>Dan
>
>-- 
>http://www.flash.net/~djconnel/

-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/POVring.html
=Bob

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Dan Connelly wrote:
> 
> Jed Reynolds wrote:
> > > 4. "interpolate 2" should almost always be used with bump maps
> > >    to prevent pixellization artifacts.
> >
> > I didn't seem to notice a lot of difference between interpolate 2
> > and interpolate 4, but I did notice the difference between 0 an {2,4}.
> 
> Bilinear interpolation is a pretty standard scheme, so I always
> use it... I haven't investigated normalized distance, so can't
> comment on the speed/quality tradeoffs.
> 
> > >
> > > Consider the following scene :
> > Now why did I put a "phong" shading in mine when I
> > should have been using "specular"...Hrm. It sharpens it quite
> > a bit. I like the effect when roughness in increased as well.
> 
> Don't take my choice too seriously..... some folks use Phong
> and others specular.  I choose the former because the docs
> claim it is more realistic, but I can't claim this is an
> otherwise educated preference.
> 
> Anyone care to comment?
> 
> Dan
> 
> --
> http://www.flash.net/~djconnel/

I've actually used both to good effect to do a finish like 'metallic'
car paint
finish{
	phong .3 phong_size 15
	specular 1 roughness 0.001 }
gives a big dull phong highlight and a small shiny spot.

PoD.

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=Bob <ver### [at] aolcom> wrote:
: 'phong' hilights have color based upon lights, whereas 'specular' is white 
: regardless of colors used in lights.

camera { location -z*8 look_at 0 angle 35 }
light_source { <100,100,-100> color <1,1,0> }
sphere
{ -x,1 pigment { rgb <1,0,0> } finish { phong 1 phong_size 10 }
}
sphere
{ x,1 pigment { rgb <1,0,0> } finish { specular 1 roughness .05 }
}


http://www.cs.tut.fi/~warp/test.jpg

  Yeah, right. And the moon is a big cheese.

-- 
                                                           - Warp. -

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Well, next thing I'm going to try to do is make some 
gas giant textures.

I presume that I would use a gradient texture with
some turbulence. Has anyone tried this before--I'm
looking for a few tips.

--jed

Jed Reynolds wrote:
> 
> I posted a couple of nice pictures about my planets and
> a brief explanation of how I made them.
> 
> http://www.scruz.net/~hed/pub/pov_planets/
> 
> pretty fun for a weekend render session, I'd say.
> 
> --jed
> 
> --
> # Jed Reynolds, mailto:jed### [at] surfsoftcom http://www.surfsoft.com/~jed
> # "...I've seen the old geeks talk to the young geeks, and they speak
> # the same language. There's no age gap or anything." --Steve Wozniak

-- 
# Jed Reynolds, mailto:jed### [at] surfsoftcom http://www.surfsoft.com/~jed
# "...I've seen the old geeks talk to the young geeks, and they speak
# the same language. There's no age gap or anything." --Steve Wozniak

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Jed Reynolds wrote:
> 
> Well, next thing I'm going to try to do is make some
> gas giant textures.
> 
> I presume that I would use a gradient texture with
> some turbulence. Has anyone tried this before--I'm
> looking for a few tips.

I've done it a little.

Yes, you use gradient.  The turbulence should be small, but with higher
than normal values for omega and lambda, which make the edges of the
banding swirly without making the bands wander all over the place.

Regards,
John

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