hello,

i made a try to look behind the the technique of isosurfaces. so i
read the Povray-documentation delivered with Povray
(file:/opt/povray35_first/share/doc/povray-3.50a/html
povdoc_082.html#target_137).
i was surprised that my results are not the same as shown in
documentation.
it should look like iso_23.gif but does look like iso_map.jpg.
as you can see i use self-compiled 3.50a-version of Povray. 
is there my mistake?
or did i missunderstood the documentation so my code is wrong?

additionally i read a isosurface-tutorial under
http://www.econym.demon.co.uk/isotut/
it is nice. but what i need is a more basic one or one even better
than Povray's. does anyone know where i can find them in net?

thanks for help in advance.

this is the code i have written:
//------------------------------>>iso_map.pov
#version 3.5

#include "functions.inc"

#declare radiosity_on=true;
//#declare radiosity_on=false;

global_settings {
        adc_bailout 0.00392157
        assumed_gamma 1.5
        ambient_light 2
        #if (radiosity_on)
                radiosity {
                gray_threshold 1
                }
        #end //if
}


#declare cam1=
camera {
        location <0,2.5,-2.5>
        look_at <0,0,0>
}

camera { cam1 }

light_source {
        <5,5,-5>
        color <255,255,255>/255
}

plane {
        y,-0.1
        pigment { color <255,255,255>/255 }
}

#declare fn_Pigm=function {
    pigment {
       agate
       color_map {
         [0 color rgb 0]
        [1 color rgb 1]
       }
    }
}
isosurface {
        function { f_sphere(x, y, z, 1.6)-fn_Pigm(x/2, y/2, z/2).gray*0.5 }
        pigment { color <255,225,32>/255}
        rotate y*-30
}
//------------------------------<<iso_map.pov

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Attachments:
Download 'iso_23.gif' (8 KB) Download 'iso_map.jpg' (9 KB)

Preview of image 'iso_23.gif'

Preview of image 'iso_map.jpg'

not### [at] availablenet news:4083e069@news.povray.org

> isosurface {
>         function { f_sphere(x, y, z, 1.6)-fn_Pigm(x/2, y/2,
>         z/2).gray*0.5 } pigment { color <255,225,32>/255}

You probably should
1) define bigger cointainer box i.e. cointained_by { sphere { 0 3 } }
2) maybe increase max_gradient

-- 
http://www.raf256.com/3d/
Rafal Maj 'Raf256', home page - http://www.raf256.com/me/
Computer Graphics

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Unless you specify the contained_by-'object', inside the isosurface, (which
limits the area where POV-Ray samples for the surface of the function) a box
{ <-1, -1, -1>, <1, 1, 1>} will be used as default.

Consult your helpfile.

Regards,

Werner Vesteraas
Oslo,
Norway

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> isosurface {
>         function { f_sphere(x, y, z, 1.6)-fn_Pigm(x/2, y/2, z/2).gray*0.5 }
>         pigment { color <255,225,32>/255}
>         rotate y*-30
> }
> //------------------------------<<iso_map.pov

I don't see a bounded_by statement in there.  Maybe if your the default
bounding box is something like box { 1, -1 } then it would certainly cut
off most of your 1.6 radius sphere.

Try inserting this statement right beneath function{...}:

bounded_by { box { 2, -2 } }


That should make the bounding box plenty big enough for your sphere.  At
least, if that IS the problem.

Budge

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> I don't see a bounded_by statement in there.  Maybe if your the default
> bounding box is something like box { 1, -1 } then it would certainly cut
> off most of your 1.6 radius sphere.
>
> Try inserting this statement right beneath function{...}:
>
> bounded_by { box { 2, -2 } }
>
>
> That should make the bounding box plenty big enough for your sphere.  At
> least, if that IS the problem.
>
> Budge


Its official.  I'm a retard.  All those "bounded_by"'s in there should be
"contained_by"

Two other people got it right before I did, though :)

Budge

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bud### [at] yahoocom news:web.4083e7168768e240a1fd027f0@news.povray.org

> I don't see a bounded_by statement in there.  Maybe if your the default
> bounding box is something like box { 1, -1 } then it would certainly cut
> off most of your 1.6 radius sphere.
> 
> Try inserting this statement right beneath function{...}:
> 
> bounded_by { box { 2, -2 } }
> 
> 
> That should make the bounding box plenty big enough for your sphere.  At
> least, if that IS the problem.
> 

All is true, but just You mistaken bounded_by with contained_by.
The second option is needed, bounded_by will be calculated automaticly, but 
You can specyfie it default (and/or another bounding-related segment - 
clipped_by)
-- 
http://www.raf256.com/3d/
Rafal Maj 'Raf256', home page - http://www.raf256.com/me/
Computer Graphics

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Rafal 'Raf256' Maj wrote:


> You probably should
> 1) define bigger cointainer box i.e. cointained_by { sphere { 0 3 }
> 

this was my problem. thank you for helping!

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