"New2Povray" <nomail@nomail> wrote in message 
news:web.48f4e301fc37f40429569840@news.povray.org...
> Hi all
>
> I am new to povray and have been trying to render a surface without much
> success,

Hi and Welcome.

> the surface could not be mathematically represented (will at least not
> in one piece) as a function,

I'll take your word for it :o)

The example pasted in below my signature illustrates one approach that you 
could quite easily use. I transformed your data into POV-Ray arrays, then 
used those arrays to build a POV-Ray mesh2 object. Transforming your data in 
this way is quite simple using an editor that supports columnar editing, 
such as the POV-Ray Windows editor. ie. to insert the commas you can click 
in the gap between two numbers in the top line, ctrl-shift-click in the 
corresponding position on the bottom line and type a comma. (repeat 7 times, 
once for each gap).

This example isn't smoothed and smoothing would require an extra chunk of 
code to calculate the mesh normals.

Alternatively you may wish to take a look at Mike Williams' excellent 
isosurface tutorial which provides a number of ways of combining functions 
(see http://www.econym.demon.co.uk/isotut/). You may find that you can 
programmatically 'chop' your different functions together.

If your full dataset follows a grid in the way this data does, you might 
want to consider writing the z values as a bitmap then using the image as a 
height field.

Regards,
Chris B.

// Example...

camera {location <0,0,-5> look_at 0}
light_source {<-10,20,-50>, rgb 1}

#declare GridSize = 7;
#declare PointCount = pow(GridSize,2);
#declare NumberOfFaces = 2*pow(GridSize-1,2);

#declare XCoord = array[PointCount] {

   -1.5000 , -1.0000 , -0.5000 ,       0  ,  0.5000 ,   1.0000  ,  1.5000 ,
   -1.5000 , -1.0000 , -0.5000 ,       0  ,  0.5000 ,   1.0000  ,  1.5000 ,
   -1.5000 , -1.0000 , -0.5000 ,       0  ,  0.5000 ,   1.0000  ,  1.5000 ,
   -1.5000 , -1.0000 , -0.5000 ,       0  ,  0.5000 ,   1.0000  ,  1.5000 ,
   -1.5000 , -1.0000 , -0.5000 ,       0  ,  0.5000 ,   1.0000  ,  1.5000 ,
   -1.5000 , -1.0000 , -0.5000 ,       0  ,  0.5000 ,   1.0000  ,  1.5000 ,
   -1.5000 , -1.0000 , -0.5000 ,       0  ,  0.5000 ,   1.0000  ,  1.5000 }

#declare YCoord = array[PointCount] {
   -1.5000 , -1.5000 , -1.5000 , -1.5000  , -1.5000 ,  -1.5000  , -1.5000 ,
   -1.0000 , -1.0000 , -1.0000 , -1.0000  , -1.0000 ,  -1.0000  , -1.0000 ,
   -0.5000 , -0.5000 , -0.5000 , -0.5000  , -0.5000 ,  -0.5000  , -0.5000 ,
         0 ,       0 ,       0 ,       0  ,       0 ,        0  ,       0 ,
    0.5000 ,  0.5000 ,  0.5000 ,  0.5000  ,  0.5000 ,   0.5000  ,  0.5000 ,
    1.0000 ,  1.0000 ,  1.0000 ,  1.0000  ,  1.0000 ,   1.0000  ,  1.0000 ,
    1.5000 ,  1.5000 ,  1.5000 ,  1.5000  ,  1.5000 ,   1.5000  ,  1.5000 }

#declare ZCoord = array[PointCount] {
    0.7781 ,  0.9975 ,  0.6816 ,       0  , -0.6816 ,  -0.9975  , -0.7781 ,
    0.9975 ,  0.8415 ,  0.4794 ,       0  , -0.4794 ,  -0.8415  , -0.9975 ,
    0.6816 ,  0.4794 ,  0.2474 ,       0  , -0.2474 ,  -0.4794  , -0.6816 ,
         0 ,       0 ,       0 ,       0  ,       0 ,        0  ,       0 ,
   -0.6816 , -0.4794 , -0.2474 ,       0  ,  0.2474 ,   0.4794  ,  0.6816 ,
   -0.9975 , -0.8415 , -0.4794 ,       0  ,  0.4794 ,   0.8415  ,  0.9975 ,
   -0.7781 , -0.9975 , -0.6816 ,       0  ,  0.6816 ,   0.9975  ,  0.7781 }

mesh2 {
  vertex_vectors {
    PointCount,
    #local I = 0;
    #while (I<PointCount)
      #if (I!=PointCount-1)
        <XCoord[I],YCoord[I],ZCoord[I]>,
      #else
        <XCoord[I],YCoord[I],ZCoord[I]>
      #end
      #local I = I + 1;
    #end
  }
  face_indices {
    NumberOfFaces
    #local I = 0;
    #while (I<GridSize-1)
      #local J = 0;
      #while (J<GridSize-1)
        #local K = I*(GridSize)+J;
        <K,K+1,K+GridSize>,
        #if (K!=NumberOfFaces-1)
          <K+1,K+GridSize+1,K+GridSize>,
        #else
          <K+1,K+GridSize+1,K+GridSize>
        #end
        #local J = J + 1;
      #end
      #local I = I + 1;
    #end
  }
  pigment {rgb 1}
}

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