I am writing a term paper on POV-RAY and ray tracing in general.  In my
research I have come accross the terms "backward", "forward" and
"hybird", as the methods of creating the algorithm to simulate the light

waves.  I was wondering which method POV-RAY uses?

Can anyone point me in the direction of where I can get information
specifically about POV-RAY and raytracing in general (history, the
original software, the original purpose, etc).

Thanks in advance,
Ric

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I think it is backwards, but it depends on what hybrid is.

it sends rays from the camera, finds which surface it hits first, checks
that against light sources directly (doesn't send out lots more rays) for
specular, phong and diffuse, and sends out two more rays for refraction and
reflection.

Hope this helps some.

PS. don't quote me on any of this.

-- 
Tristan Wibberley

(Remove the '.NO_LUNCHEON_MEAT' from my
email address to reply.)


Ric Mitchell <ric### [at] wizardnet> wrote in article
<34D### [at] wizardnet>...
| I am writing a term paper on POV-RAY and ray tracing in general.  In my
| research I have come accross the terms "backward", "forward" and
| "hybird", as the methods of creating the algorithm to simulate the light
| 
| waves.  I was wondering which method POV-RAY uses?
| 
| Can anyone point me in the direction of where I can get information
| specifically about POV-RAY and raytracing in general (history, the
| original software, the original purpose, etc).
| 
| Thanks in advance,
| Ric
| 
| 
| 
|

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On 11 Feb 98 15:59:39 GMT, "Tristan Wibberley"
<tri### [at] compaqcom> wrote:

>I think it is backwards, but it depends on what hybrid is.
>
>it sends rays from the camera, finds which surface it hits first, checks
>that against light sources directly (doesn't send out lots more rays) for
>specular, phong and diffuse, and sends out two more rays for refraction and
>reflection.

Only two things I'd add:  

(1) Specular doesn't mean the same thing to most people that it does
to POV-Ray.  The 'specular' parameter to the finish statement in POV
does not control specular reflection; that is controlled by the
'reflection' parameter.  'specular' controls the size of specular
highlights.  The specular you are talking about is the computation of
those highlights.

(2) POV also traces to each light source to determine shadowing, so it
does trace one additional ray per light source for each intersection
with a diffuse surface (more for area lights), but it doesn't handle
refraction or reflection for those rays.

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