leosti wrote:
> Hello-
> 
> This is my first posting (just (re) started using POV).  The enclosed image
> is made from an isosurface for the towers and a height field for the
> swimming thing.  
> 
> The isosurface is a repeating, with modifications at each repetition,
> function using the mod (to cause repeats) and div (to discretely change
> certain parameters for each copy); following ideas presented in some recent
> discussion on POV news. I am quite happy with the result, except for a few
> things:
> 1)it renders quite slowly (this took about 30 hours on a 1.4GHz PIII, of
> course radiosity and focal blur are used.)
> 2)the wake needs work
> 3) there is an artifact (boxed in red) of a sort I have not seen before in
> the isosurface. I imagine upping the accuracy 0.002 and max_gradient 40
> (current settings) will help.
> 
> Interestingly POV reports a max_gradient of over 3000 when it renders.  I
> suspect this is due to the DIV statements discontinuous nature; but it makes
> it hard to know what the max_gradient of the continuous surface should be.

The max_gradient does not have to do anything with the continuity of the 
*surface* but with the continuity of the *function*.  When you generate 
a repetitive function with mod() but vary the different repetitions it 
will be very hard to get a continuous function (to be precise you will 
have to make sure the variation drops to zero at the repetition 
borders).  Looking at your image - you'd probably have it much easier 
(and faster) by using a separate isosurface for each of these 'columns'.

Christoph

-- 
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 25 Oct. 2003 _____./\/^>_*_<^\/\.______

Post a reply to this message