On 22/06/2015 05:07 PM, clipka wrote:
> PBR avoids old-school shading models and rendering algorithms that were
> designed to achieve a particular effect, and instead uses mechanisms
> that were designed to model the underlying physical processes.
>
> POV-Ray has been heavily geared towards PBR in recent times, and UberPOV
> should by now be a viable PBR tool, provided you stick to the following
> rules:

I don't know, man. Like, in the beginning, everybody did scanline 
rendering, which is very fast and just barely capable of crudely 
approximating enough effects to be almost believable.

And then people started using ray-tracers, which "model the real 
physics" to achieve far more realistic results. They work by directly 
tracing individual rays of light, rather than trying to fake it somehow 
with clever short-cuts. Things like physically correct specular 
reflection on curved surfaces are trivial for a ray tracer, but 
notoriously difficult with scanline rendering.

...except that classical ray-tracers are *still* using short-cuts. Like 
point-lights. These do not exist in the real world, but look just about 
convincing enough that it can look OK. Or "ambient light", which is a 
crude approximation to global diffuse inter-reflection...

So people start adding hacks like photon maps and pre-computed radiosity 
to try to work around the defects.

And now, people just run unbiased renderers on the GPU which *directly* 
simulate all manner of effects like caustics and diffuse reflection 
properly, by simply computing *all* light paths by brute force...

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