In article <web.3f9f529736b6a6bb3c1dcda40@news.povray.org>,
 "Kronix" <kro### [at] hotmailcom> wrote:

> I have a black and white image, say for instance, a white circle on a black
> background.  Is there a simple way to create an object by extruding the
> white circle (lying in, say, the xy plane) some distance along the z-axis?
> This would, of course, create a cylinder along the z-axis.  In other words,
> how can I extrude portions of a b&w imagemap?

A start would be a height field. This is far from ideal, however...the 
sides of the cone will be vertical surfaces of the height field, and 
there will be severe tessellation artifacts. Alternatively, you could 
use the image as input as the function for an isosurface...use the image 
in an image_pattern image function, and use interpolation. (Isosurfaces 
don't handle the infinite gradients between non-interpolated pixels very 
well.)


> Say I change my 2-bit imagemap into a 16-bit grayscale imagemap.  Can I now
> extrude my image in the z-direction... only associate a transparency with
> each pixel value?  Black might be completely transparent, while white would
> be totally opaque, etc.

I think what you're really looking for here can be had by using the 
image_map as the density for scattering media in a box.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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