On 14-1-2010 2:16, nemesis wrote:
> andrel wrote:
>>> I think is that ATM GPU's are useful for trangulations and
>>> that the  result is near real life. As far as I have heard the
>>> rendering is less physical correct and more is faked. I though they
>>> were a bit lacking in multiple reflection and refraction, in media
>>> and possibly also in versatility of procedural textures. I am not a
>>> gamer, so I don't actually know for sure.
>>>
>> So, point me to where I talked exclusively about game tech.
> 
> "less physical correct", "lacking reflection and refraction", "lacking 
> media" and "lacking procedural textures" are all indeed game tech 
> limitations (for now) 

Probably, yet going from that to the converse is a logical fallacy.

> that don't show up at all in the "physically 
> correct" path tracer running on GPU I linked to.

How do you know?

>> But let me try to explain again: what you pointed at and other things 
>> I have seen so far is that GPUs are used for a limited set of 
>> primitives only, modelling a subset of physical behaviour. Even if 
>> they claim to be physically accurate in practice they aren't
> 
> GPU's don't claim anything.  General purpose algorithms making use of 
> their sheer math processing power do.

To be even more pedantic: it is the people that write software who claim 
things.

> I thought by physically correct you were talking about materials or 
> light propagation behavior, not every model being made of from polygons.

No I made both statements: they are less physical correct and don't 
support all primitives of POV. Until both problems are solved it is not 
sensible to try to port POV to a GPU.

>>  Again what I have seen and understood is that up till now POV is more 
>> physical complete (disclaimer: I have not seen everything that is out 
>> there.). Hence POV still has a place.
> 
> and I hope that place is a GPU.

Why? I mean why a GPU especially? There is a lot going on and I don't 
see a reason to single out GPUs. I want my ray tracer to run as facst as 
possible, I don't really care on what hardware it is implemented, as 
long as it is affordable.

>> In order to get more 'realistic' games the GPUs have been optimized to 
>> render textures and fake reflections and shadows. They can be used as 
>> FPU replacement for certain tasks, but they are not perfect for 
>> general processing (yet). That is as far as I know. There may have 
>> been significant advances that I have missed because I am not a gamer 
>> and hence do not follow the developments closely.
> 
> I'm not talking about games at all. 

Good, me neither.

> I only hinted at the fact that 
> several other raytracers are beginning to use the GPU for their 
> calculations, including full raytraced reflections, refractions, 
> mesh-based lighting etc.  They are not using the GPU as a mere game 
> scanline engine,  they are just general purpose programs (actually, 
> parts of it) running on GPU.

I fail to see why it is necessary to repeat what I already indicated to 
know. Has the fact that I don't share your conclusion something to do 
with it? If that is the main reason, my estimate is that if you just 
repeat yourself, I am not going to change my opinion.

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