In article <39647B53.CC2D4732@mitre.org>, xan### [at] mitreorg wrote:

> Not being too up on how volumetrics are done in Mega-POV, I'll try to
> relate the methods.  I use a very traditional ray marching algorithm. 
> Samples are taken at fixed intervals along the ray.  There's some
> attempt to limit the number of samples through: use of bounding box (if
> any), minimum # of samples/ray, maximum # of samples/ray, opacity cutoff
> level, light influences, etc..

This sounds similar to MegaPOV method 2 media. It takes evenly spaced 
samples, and produces images without the graininess of the official 
version(called method 1 in MegaPOV), but has problems with banding and 
jagged edges. There is a method 3 which performs supersampling at areas 
where the samples vary by more than a threshold level, this kind lacks 
most of the artifacts of method 2 and is nearly as fast.


> >      - Multiple microfacet models
> >         (MegaPOV has a blinn model alongside the phong and specular
> > models, does that count?)
>   Just add: Cook, Gaussian, and Reitz.

Do you know of any online papers about these?


> >      - Lens flares
> >         (POV-Ray plugins exist for this for the official version)
> 
> As objects, which affects speed of rendering.  Given the nature of lens
> flares (things happening within the series of elements making up a
> lens), this is more properly handled as a post process.  I would guess
> that the official version doesn't account for visibility of the light
> when determining which flares to draw.

There are two lens flare includes which I know of, and at least one of 
them can do "hiding" of a lens flare behind an object. However, though I 
have installed both of these "plugins", I have never actually used them, 
so I don't really know what I am talking about. :-)

-- 
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://homepage.mac.com/chrishuff/
TAG Web page: http://tag.povray.org/

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