scott wrote:
>> ask for a sphere, I get a sphere. Not some polygon mesh approximating 
>> a sphere, but AN ACTUAL SPHERE.
> 
> In the end you get a bunch of pixels approximating a sphere though, so 
> as long as your polygons are roughly the same size as pixels, you won't 
> get anything worse than a true sphere.

Yeah - and when does GPU rendering ever use polygons even approaching 
that kind of size? Oh yeah - never.

>> Surfaces and 
>> textures can be magnified arbitrarily and never look pixellated.
> 
> That's just because they're procedurally generated and not textures.  
> You can do the same on a GPU if you want (but usually a texture is 
> faster, even a really big one, probably is in POV too for moderately 
> complex textures).

Procedural textures have advantages and disadvantages. Personally, I 
prefer them. But maybe that's just me. Certainly I prefer procedural 
geometry to polygon meshes...

>> Reflections JUST WORK. Refraction JUST WORKS. Etc.
> 
> What you mean is, the very simplistic direct reflection and refraction 
> in POV "just works".  Try matching anything seen in reality (caustics, 
> blurred reflections, area lights, diffuse reflection, focal blur, 
> subsurface scattering) and you enter the world of parameter tweaking.

Well it works a damn site better than in GPU rendering solutions - and 
that's what I was comparing it to.

(Besides, for caustics, you turn on photon mapping and adjust *one* 
parameter: photon spacing. Set it too low and the caustics are a bit 
blurry. Set it too high and it takes months. Experiment. Area lights are 
similarly straight-forward. Radiosity takes a lot more tuning, but 
photons and area lights are both quite easy.)

>> (OTOH, the fast preview you can get sounds like a useful feature. Ever 
>> wait 6 hours for a render only to find out that actually it looks 
>> lame? It's not funny...)
> 
> I usually do lots of quicker renders first, one without radiosity/focal 
> blur/area lights to make sure the geometry is placed correctly.  Then do 
> a low-res render with radiosity and area lights to check that the 
> colours/brightness looks ok overall.  Then maybe another high res one 
> with just focal blur to make sure I have enough blur_samples.  Then 
> finally do the big one with everything turned on.  And pray ;-)

Being able to get a fast but grainy preview certainly sounds useful in 
this respect. I guess it depends on just *how* grainy. (I.e., how long 
it takes for the image to become clear enough to tell if it needs 
tweaking. Presumably that depends on what the image is...)

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message