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Lightwolf
04-29-2013, 12:25 PM
Hi there,

we've just published an interview (http://www.db-w.com/products/exrtrader/stories/202-from-a-midsize-town-in-sweden-into-the-world) with Mikael "cageman" Burman about his work in LightWave and especially his work on FarCry at Massive in Sweden.

We hope you'll enjoy it.

Cheers,
Mike

Greenlaw
04-29-2013, 05:04 PM
Cageman is one of my 'LightWave Heroes'. Thanks for posting this.

Okay, so what's db&wBOT and why are you keeping it a secret from us? :)

G.

Phil
04-29-2013, 05:17 PM
Spherical harmonic lighting. Yes, please :)

Lightwolf
04-29-2013, 06:01 PM
Cageman is one of my 'LightWave Heroes'. Thanks for posting this.
He's certainly a great guy...

Spherical harmonic lighting. Yes, please :)


Okay, so what's db&wBOT and why are you keeping it a secret from us? :)
Well, it's an incubatory for ideas and proof of concept code. Right now there isn't that much in it. frameD started out there (just the loader). Then there's the SH light and nodal shader (unfortunately there's issues in the LW SDK which prevent both from working as I'd like them to, which means that they won't be released as is).

The SH light works like a dome light with a HDRI, but produces a (approximated) diffuse result with just one sample. It can cast further rays for shadows, which then essentially work like ambient occlusion. The result is very similar to backdrop radiosity.

Another one is a simple point light to test if an inverse square falloff could be coupled with a (soft) cutoff to speed up renders (inverse and inverse square falloffs never reach an intensity of 0%, causing LW to evaluate those lights anywhere in a scene). It could be and it does... but the light is just a start and not fully featured (i.e. no PRMBlur support for example).

So essentially it's a more or less random collection of code to try things... some of which may be useful in very specific cases. And some that highlight problems. ;)

Having said that... we also have a wiki of ideas that have no code written at all so far. :)

Cheers,
Mike

djwaterman
04-29-2013, 07:53 PM
SHL, you mean like a HDR lighting that produces cast shadows like in VRay and Modo?

jasonwestmas
04-29-2013, 08:08 PM
Cageman. . .more geeky than I. Hard to do. ;) I appreciate his insight.

Lightwolf
04-29-2013, 08:35 PM
SHL, you mean like a HDR lighting that produces cast shadows like in VRay and Modo?

http://www1.cs.columbia.edu/~ravir/papers/envmap/

I think what you mean is importance sampling. And yes, I am toying with the idea as well (no more though at the moment).

Cheers,
Mike

Greenlaw
04-29-2013, 09:43 PM
Cool! Thanks for sharing this info Mike. :)

geo_n
04-29-2013, 09:51 PM
SHL, you mean like a HDR lighting that produces cast shadows like in VRay and Modo?

You mean this? http://www.spot3d.com/vray/help/maya/150R1/tutorials_sph_harm.htm
Drawback for SH is complex scenes produce artifacts.

Lightwolf
04-30-2013, 04:59 AM
You mean this? http://www.spot3d.com/vray/help/maya/150R1/tutorials_sph_harm.htm
Drawback for SH is complex scenes produce artifacts.
That depends on the use. Weta used them to great effect to cache occlusion in Avatar and Tin Tin (using a proprietary CUDA based renderer co-developed with nVidia).

http://www.nvidia.com/object/wetadigital_avatar.html

Cheers,
Mike

geo_n
04-30-2013, 05:56 AM
Interesting. Wonder how it compares to pathtracers or other gpu renderers.
I'm more interested with having custom buffers in lw though :D so I could plug more dpnfe into exrtrader with unlimited custom buffers like vray can.

Lightwolf
04-30-2013, 06:05 AM
Interesting. Wonder how it compares to pathtracers or other gpu renderers.
It doesn't... because it only pre-computes occlusion, stores that using SHs and those in turn are used for the final render (PRMan if I'm not mistaken).
However, the occlusion can be re-used.

I'm more interested with having custom buffers in lw though :D so I could plug more dpnfe into exrtrader with unlimited custom buffers like vray can.
On the to-do list. Unfortunately, that also includes a complete re-write and the GUI will need to change completely as well.

Cheers,
Mike

Ztreem
04-30-2013, 06:25 AM
Nice read, thanks for sharing.

allabulle
04-30-2013, 06:30 AM
yup, nice read indeed. Thanks.

stobbs
04-30-2013, 10:11 AM
Very Interesting interview I've always found cagemans tutorials really helpful.

Mike, is your SH light similar to denis's dp dome light which samples background images and gradients?

geo_n
04-30-2013, 10:16 AM
It doesn't... because it only pre-computes occlusion, stores that using SHs and those in turn are used for the final render (PRMan if I'm not mistaken).
However, the occlusion can be re-used.

On the to-do list. Unfortunately, that also includes a complete re-write and the GUI will need to change completely as well.

Cheers,
Mike

Ah I thought the article mentioned Pantaray as full blown renderer. Reread and it says pre-computation engine.
Looking forward to custom buffers in exrtrader. :D

Lightwolf
04-30-2013, 10:26 AM
Mike, is your SH light similar to denis's dp dome light which samples background images and gradients?
In a way.. it only works with an image (not a general backdrop, even though that's on my todo list). It doesn't really sample it, but precomputes the SH (which is currently 6 values per RGB channel) by going over the pixels once. Unfortunately, it needs to do so for every new frame (including just stepping through frames in Layout), since it can't differentiate between image sequences and still images (there's just no SDK hooks that I've found).
Which is one of the main reasons as to why it's not released. I know I can't work around all limitations - but I find this one unacceptable, thus the plugin isn't fit for the public.


Ah I thought the article mentioned Pantaray as full blown renderer. Reread and it says pre-computation engine.
I suppose it's the best of both worlds... use the GPU to speed up the heavy lifting on relatively small data sets (as in: single items such as plants) - then let the software renderer assemble the final shot.
Certainly not a pipeline for everybody though.

Cheers,
Mike