[Bf-committers] Google Summer of Code 2008 Proposal: Lightcuts

[trip somewhere]

That sounds sweeeet! A faster way to test renders is always wanted by
users aside from the dream and mis-knowledge of gpu rendered off
loading.
Good luck in it ::D

On Sat, Mar 22, 2008 at 6:08 AM, Davide Vercelli
<davide.vercelli at gmail.com> wrote:
> Hi guys,
>
>   I would like to submit a Google SoC proposal concerning the
>  implementation of the Lightcuts algorithm [1].
>
>   The Lightcuts algorithm is a way to handle large number of lights
>  (thousands) by selecting a different representative subset per pixel
>  (hundreds), according to perceptual error metrics. Handling large
>  number of lights is very useful as it can be used to unify lighting
>  from various sources (textured area lights, volume lights, environment
>  maps) by conservatively converting them into a large number of point
>  lights.
>
>   Users would benefit from significant speedups in scenes with complex
>  lighting; additionally, very fast preview renderings can be generated
>  by raising the error threshold.
>
>   The original Lightcuts algorithm is not only effective but very
>  practical, and my opinion is that it should fit into blender's
>  existing ray tracing engine without major disruptions (to existing
>  code, workflow, etc.).
>
>   The algorithm per se is relatively simple, but implementing it
>  properly and efficiently is tricky [4] and integrating it into
>  blender's rendering code, which is notoriously not for the
>  faint-hearted, could prove a good project alone. My fear though is
>  that it could be deemed too easy to implement as a SoC project. Here
>  are some possible extensions:
>
>   a) adding an instant radiosity-like scheme [2], that is: primary
>  lights generate a large number of secondary lights acting as indirect
>  light sources; this way, blender internal would gain indirect
>  lighting, albeit approximated
>
>   b) implementing reconstruction cuts [1], a screen space
>  interpolation scheme to cut rendering times even more, though I'm
>  afraid that this could be difficult to integrate in the current
>  rendering code
>
>   c) implementing Multidimensional Lightcuts [3], which is an
>  extension to the original algorithm handling depth of field, motion
>  blur, participating media, antialiasing and other effects; this seems
>  to be way more difficult to implement and, again, I'm not sure how
>  well it would play with the existing rendering pipeline
>
>   So, before submitting the actual proposal, I would like to hear if
>  it would be a good idea to include one of these extensions to the
>  original algorithm and which one. (I favour option "a" both as a coder
>  and as a user).
>
>   Any other comments or suggestions would be highly appreciated.
>
>   Finally a couple of notes about me: I am an Italian post-graduate
>  student and rendering is among my research interests. I am an active
>  member of the Italian Blender community since 2005. I have no problems
>  with C, C++ and Python, and I do know blender internals a bit (I have
>  also submitted a number of patches to the tracker, even though mostly
>  small UI tweaks). I do need a lot of mentoring on rendering code,
>  though... ;)
>
>   Cheers,
>
>  Davide Vercelli / UncleZeiv
>
>  References:
>  [1] B. Walter et al, "Lightcuts: a scalable approach to illumination"
>  (Siggraph 2005)
>     http://www.cs.cornell.edu/~kb/projects/lightcuts/
>  [2] A. Keller, "Instant Radiosity" (Siggraph 1997)
>     http://citeseer.ist.psu.edu/keller97instant.html
>     This is just the original seminal paper, the literature on this
>  subject is broad.
>  [3] B. Walter et al, "Multidimensional Lightcuts" (Siggraph 2006)
>     http://www.cs.cornell.edu/~kb/projects/mdlc/index.htm
>  [4] M. Miksik, "Implementing Lightcuts" (CESCG 2007)
>     http://www.cescg.org/CESCG-2007/papers/Prague-Miksik-Miroslav/Lightcuts_MiksikMiroslav.pdf
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