Jump to content
  • Advertisement
Sign in to follow this  
Thr33d

Sh or All frequency Shadows

This topic is 4827 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hey everyone, I don't spend enough time coding, so I actually haven't implemented SH for lighting yet, but I was wondering if anyone had taken a real-life shot at implementing SH and/or the method described in the All-Frequency Shadows paper It claims to be a magnitude faster than SH. What's the word? -Michael g.

Share this post


Link to post
Share on other sites
Advertisement
While I didn't implement the method outlined in that paper, I implemented many different SH systems.

To be honest, I've never been a big friend of spherical harmonics. They have their uses, and they can look nice, but they're just too low frequency to be really usable in a higher quality context. That's an inherent problem of the technique: the more octaves you add in, the higher frequencies you can represent - but the lower is the performance. For largely static geometry, GI generated (possibly directional) lightmaps will both outperform SH and result in better quality.

Now, a different mathematical approximation can alleviate the problem. Wavelets have been a promising candidate pretty much since SH came around, but were never really usable in realtime. The paper you linked to looks interesting though, and it might be worth a try to run some tests on the spectral range of their technique compared to SH.

I'm afraid that the only real way to know, is to implement it and see for yourself :)

Share this post


Link to post
Share on other sites
Quote:
Original post by Thr33d
It claims to be a magnitude faster than SH. What's the word?


doubtful, i think what they mean is for all frequency shadows, wavelets are faster(cuz' in high frequency case, it uses relatively lower number of coefficents, while for low frequency case, SH are faster).

Share this post


Link to post
Share on other sites
I've implemented both. They're both pretty simple to learn and use. The problem with representing high frequency effects and shadows (and be able to make use of the fact that you can rotate lighting etc with out re-computation) is that you need very detailed meshes to see the effects. Indeed it is true that wavelets are faster methods of rendering over spherical harmonics, but this is only for high frequency signals (as sh would require hundreds of bands to represent the same information).

Check out the pictures of how detailed my mesh had to be for small area lights:

http://www.cs.bath.ac.uk/~cspmsb/waveletlighting/1L_100.jpg

http://www.cs.bath.ac.uk/~cspmsb/waveletlighting/1L_10000.jpg

This noise might have been from my hemicube code however.

http://www.cs.bath.ac.uk/~cspmsb/waveletlighting/Grace_10000.jpg

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

We are the game development community.

Whether you are an indie, hobbyist, AAA developer, or just trying to learn, GameDev.net is the place for you to learn, share, and connect with the games industry. Learn more About Us or sign up!

Sign me up!