> I'd rather use a function pigment for that - much faster than parsing
> a gazillion boxes.

To use boxes for postwork within Pov-Ray is exactly what I did in my last
two IRTC entries.
The method is awfully slow (compared with photoshop) and needs huge amounts
of memory
(a 1200*1600 render would need more than 1 GB !).

How can I use functions instead of pigments? I tried and failed so far.


Norbert

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In article <4vnrju8p4dnopfhb4ckuc4narsdevjg2j5@4ax.com>,
 Peter Popov <pet### [at] vipbg> wrote:

> >(you render in a 48 bits PNG, you use it as an image_map
> >  that fits exactly the screen, and you process it using
> >  eval_pigment and reconsturct the image with colored
> >  boxes)
> 
> I'd rather use a function pigment for that - much faster than parsing
> a gazillion boxes.

That's a good idea...you could do the same thing as the post_process 
curves filter without needing the patch, though it would still have the 
limitations of what you can put through a PNG file. A image_map pigment 
function run through three spline functions and combined into the final 
image with an average pigment would do the trick:

#declare imgFn = function {pigment {image_map {...}}}
#declare rCurveFn = function {spline {...}}
#declare gCurveFn = function {spline {...}}
#declare bCurveFn = function {spline {...}}

...
pigment {average
    pigment_map {
        [pigment {function {rCurveFn(imgFn(x, y, z).red).x}
            color_map {[0 rgb 0][1 rgb < 3, 0, 0>]}}]
        [pigment {function {gCurveFn(imgFn(x, y, z).green).x}
            color_map {[0 rgb 0][1 rgb < 0, 3, 0>]}}]
        [pigment {function {bCurveFn(imgFn(x, y, z).blue).x}
            color_map {[0 rgb 0][1 rgb < 0, 0, 3>]}}]
    }
}

I used three splines here to make it easier to adjust each channel 
separately, since splines use vectors you should be able to use just one 
spline. You could also do things like use a spline value to scale the 
color according to the brightness of the color.

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/

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On Mon, 22 Jul 2002 23:05:20 +0200, "Gilles Tran" <tra### [at] inapginrafr> wrote:
> - Rendered with povray 3.5

Respect!

ABX

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Christopher James Huff wrote:

> That's a good idea...you could do the same thing as the post_process 
> curves filter without needing the patch, though it would still have the 
> limitations of what you can put through a PNG file.

What's the bit-depth limit ?

Fabien.

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In article <3D3### [at] skynetbe>,
 Fabien Mosen <fab### [at] skynetbe> wrote:

> > That's a good idea...you could do the same thing as the post_process 
> > curves filter without needing the patch, though it would still have the 
> > limitations of what you can put through a PNG file.
> 
> What's the bit-depth limit ?

48-bits per pixel, which I assume is 16 bits per component. 65536 levels 
per component, in the range 0-100%. The C "float" type, which POV uses 
for color components internally, is at minimum a 32-bit floating point 
number, which can handle a huge range of values and is much more precise 
in the 0-1 range.
Plus you might run into problems with gamma correction.

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/

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This is excellent... as usual.







Philippe

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Apache wrote:

> Yes, please render a 80000 x 60000 pixel version for me.

Jesus, how big are you going to print it?


-- 
___     ______________________________________________
  | \     |_         website: http://davidf.faricy.net/
  |_/avid |ontaine           email: <dav### [at] faricynet>

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Gilles Tran wrote:
> 

Ye gods.  Put this in your resume when you apply to work for
Dreamworks or Pixar.

Regards,
John

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Gosh. I feel more humble than usual now.
Feels serene in spite of the tree's reflection.

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> - Regrets : the lighting.
Jeez, man -- stop apologizing!  You're giving Norbert Kern a run for his 
money (and leaving the rest of us unsticking our jaws from the floor :)!

(I haven't had a chance to *touch* my copy of 3.5 since I installed 
it... whaah. :_(

- Kevin R.

Gilles Tran wrote:
> Jpeg compression wasn't too kind on this one :( Well I'll put some close-ups
> and details on my site sometimes in the next months.
> 
> - Rendered with povray 3.5
> - Uses low quality radiosity (count 10 error_bound 1...)
> - Terragen sky
> - Terrain modelled with World Machine (beta)
> http://students.washington.edu/sschmitt/world/ (great prog, BTW)
> - Render time at 1200*1600 takes 6 hours and 600 MB of RAM (P4, 1.7Gz, 1Gb
> RAM)
> - 15000 plants with something like 20 different Xfrog models, all by me
> except the main tree, the small bushes and trees in the background, and some
> grass. The "evil" tree is by me too. 2000 leaves and twigs in the pond.
> Possibly I'll make some of the plants available later this year.
> - The hardest part was to create the backlit leaves for the main tree. For
> this I had to make "fleshy" leaves and fill them with scattering media. I
> wish I could have done it on all the plants, but either I'll wait for faster
> machines or find a better solution for backlit translucent material. Some of
> the flowers were double_illuminated.
> - Dragonflies modelled in Rhino with the demo version (before I bought it).
> They'll surely look better at the final full res of 6000*8000 which is
> rendering now.
> - The frog is a Poser one. It's almost invisible at 600*800 but it's
> there...
> - Regrets : the lighting. I had a lot of trouble with it, as the original
> image
> is not very gamma-tolerant : it looked ugly on low-gamma monitors and much
> too dark on others. I had to find a middle way so I tweaked the tones in
> post-process and some colors were lost (and there's some extra graininess
> too). I hope it looks right on your PC or Mac.
> 
> G.
> 
> --
> 
> **********************
> http://www.oyonale.com
> **********************
> - Graphic experiments
> - POV-Ray and Poser computer images
> - Posters
> 
> 
> 
> 
>

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