Ron Parker wrote:

> I find it interesting that every image processing program I've ever seen
> has a filter to differentiate the image along a direction (usually called
> "emboss") but none seem to be able to do the inverse operation; that is,
> integrate the image along a direction.  If you could, you could then take
> a carefully-controlled photograph of a penny (might need to paint it flat
> white first, to remove the specular highlights) and use the integrate
> feature to recover the contours.

    Or just put a penny on a scanner.

    As to and inverse operation, I don't see what you mean. But there is
always a separate inverse function, the photonegative.

    And there is also almost always the "stamp" filter instead of emboss
which often works much better for things where emboss appears to be the right
thing but doesn't work. And with stamp you should get control of edge depth
and direction.

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On Wed, 12 Jan 2000 22:46:35 -0500, Matt Giwer wrote:
>    Or just put a penny on a scanner.

That doesn't give you a depthmap, and it doesn't give you something you 
could integrate to get a depthmap (the light is coming from in front, so
there are no shadows.)

>    As to and inverse operation, I don't see what you mean. But there is
>always a separate inverse function, the photonegative.

I mean inverse in the mathematical sense, as in "the operation you'd perform
to undo the emboss operation."

>    And there is also almost always the "stamp" filter instead of emboss
>which often works much better for things where emboss appears to be the right
>thing but doesn't work. And with stamp you should get control of edge depth
>and direction.

But it does the same basic operation as emboss, which is differentiation.
I want a filter that integrates.

I could of course write one that works on PPM files, which would be good 
enough for my purposes.  Maybe when I have more free time... (like that'll
ever happen)

-- 
These are my opinions.  I do NOT speak for the POV-Team.
The superpatch: http://www2.fwi.com/~parkerr/superpatch/
My other stuff: http://www2.fwi.com/~parkerr/traces.html

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I think i tried that but i will try it again...
Was not happy w/ image result from HF...
Maybe i did something incorrectly...?

Matt Giwer wrote:

> ryan mooney wrote:
>
> > Thank You, Could Send/Post Me Some Examples ( Bump Map Is Not Something I
> > Am Proficient At Yet) The Coin Site Would Be Nice Too I f You Can
> > Remember.. Oh Well Guess I Will Keep Searching...
>
>     You can also use and image map. This is code is from early in my POV
> experience. There must certainly be better ways to do this.
>
> #declare coin =  union
> {
> intersection
>   {
>    height_field {
>     gif "coin2b.gif"
>     smooth
>     texture {cyltex2} // pigment {color <1,0.7,0>}
>     translate <-.5, -.5, -.50>
>     scale <1, 0.0275, 1>
>          } // end height_field
>    cylinder { <0,-.0137,0> <0,0.2,0> 1 translate <0,0.0,0> }
>   }
>  cylinder { <0,-.0137,0> <0,-0.1,0> 0.42 translate <0,0,0.01>
>    texture  {cyltex2}}//color <1,0.7,0>} }
> rotate <0,45,0>
> translate <xloc, 1.604, zloc>
> }
> coin
>
> http://giwersworld.org/artii/giants5a.jpg for the result.

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ryan mooney wrote:

    In development the problem I ran into was getting the .gif right. I had to
revise it several times, note the 2b. Everything but what I wanted "raised" had
to be exactly the same black pixels. Almost was not good enough. Anything else
had bumps in all the wrong places. Doing it today, I would not use .gif as there
is are too few intensities for smooth transitions.


> I think i tried that but i will try it again...
> Was not happy w/ image result from HF...
> Maybe i did something incorrectly...?
>
> Matt Giwer wrote:
>
> > ryan mooney wrote:
> >
> > > Thank You, Could Send/Post Me Some Examples ( Bump Map Is Not Something I
> > > Am Proficient At Yet) The Coin Site Would Be Nice Too I f You Can
> > > Remember.. Oh Well Guess I Will Keep Searching...
> >
> >     You can also use and image map. This is code is from early in my POV
> > experience. There must certainly be better ways to do this.
> >
> > #declare coin =  union
> > {
> > intersection
> >   {
> >    height_field {
> >     gif "coin2b.gif"
> >     smooth
> >     texture {cyltex2} // pigment {color <1,0.7,0>}
> >     translate <-.5, -.5, -.50>
> >     scale <1, 0.0275, 1>
> >          } // end height_field
> >    cylinder { <0,-.0137,0> <0,0.2,0> 1 translate <0,0.0,0> }
> >   }
> >  cylinder { <0,-.0137,0> <0,-0.1,0> 0.42 translate <0,0,0.01>
> >    texture  {cyltex2}}//color <1,0.7,0>} }
> > rotate <0,45,0>
> > translate <xloc, 1.604, zloc>
> > }
> > coin
> >
> > http://giwersworld.org/artii/giants5a.jpg for the result.

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