what does "sampling" really do?

[sudark]

simply said, what does "sampling" really do?

 

i know it makes images better and makes rendering times longer. so it is a quality: time relationship. i know how to use it and get good results. but im wondering more about how sampling works. the technical side to it. what does it do to the pixels and how is it related to the maps we put in the materials?

 

i have read some articles but they only deal with it cursorily

 

thanks in advance

[Nic H]

chris nichols gnomonology vray sampling tutorial quicktime is great and cheap

http://gnomonology.com/tutorial/62

7$

[JamesTaylor]

chris nichols gnomonology vray sampling tutorial quicktime is great and cheap

http://gnomonology.com/tutorial/62

7$

 

i'll second that!

[blowback]

That DVD is good, but are you asking about render theory and mathimatices ?

[sudark]

thanks for the link, i think ill check that out. but yea i am actually looking for the theory and math side to it. im no mathematician, but i am interested for the sake of knowing basically how it works

[blowback]

http://www.realtimerendering.com/books.html

 

google is your friend;)

[intero_ua]

Here's one that's better than cheap..it's free (week 17-image

sampling)

http://www.cgarchitect.com/upclose/VI/default.asp

[Eric Sosa]

Here's one that's better than cheap..it's free (week 17-image

sampling)

http://www.cgarchitect.com/upclose/VI/default.asp

yep, great info

[blowback]

I thought this was about math......?

[Christopher Nichols]

Want the real simple math explanation?

 

In the real world we have the benefit of having infinite rays all the time. Therefore to our eyes, everything looks clear and noise free.

 

We don't have that luxury on the computer. We need to shoot a bunch of random rays out there and see what we get from that sample of rays. Problem is, we get spotty looking stuff. So the key is to find the most optimal sampling based on things we know or find out along the way.... Enter higher math... You need some special algorithms to find better samples. Better samples means you get a cleaner solution faster. For example...

 

http://en.wikipedia.org/wiki/Monte_Carlo_method

 

Actually in this link you will see they mention battle ship which is an excellent example.

 

This is a fairly common method of finding samples... most high end raytracers use methods like these days, even if SOME claim to have a patent on QMC. But IMHO, that is like patenting addition. Then again Pixar patented Stochastic sampling...

[blowback]

Thanks Christopher,

 

that was an eloquent explanation. It helps me get my head around it a little better.

[sudark]

thanks for the help guys, i get the sampling thing better now. Christopher's explaination helps a lot. its simple and clear