That's great Ahmidou, looking forward to it. Sent from my iPhone
> On Dec 13, 2013, at 2:27 AM, Ahmidou Lyazidi <[email protected]> wrote: > > The problem with mean value coordinates is that they're negative with concave > cages, > and harmonic coordinates more complex and slower to generate. > I already implemented this paper in ICE: > http://www.wisdom.weizmann.ac.il/~ylipman/pmvc/pmvc.htm > The result is pretty closed to harmonic coordinates, and you dont need a > static cage as reference. This mean that you can tweak > the enveloped cage in pose and see the result on the deformed object. > I was thinking to release it for free at some point, so this might be the > occasion, and could eventually save you a few days. > I'll try to put it somewhere on the web it this weekend. > > Cheers. > > ----------------------------------------------- > Ahmidou Lyazidi > Director | TD | CG artist > http://vimeo.com/ahmidou/videos > http://www.cappuccino-films.com > > > 2013/12/13 Ben Houston <[email protected]> >> Turns out mean value coordinates on closed polygon meshes to do deformation >> was already done: >> >> http://www.cs.rice.edu/~jwarren/papers/meanvalue.pdf >> >> -ben >> >> >> >>> On Thu, Dec 12, 2013 at 9:45 AM, Ben Houston <[email protected]> wrote: >>> I guess you are referring to this... >>> >>> http://graphics.pixar.com/library/HarmonicCoordinates/paper.pdf >>> >>> The scan conversion bit with the laplacian solver seems like a lot of work. >>> >>> There is the idea of mean value coordinate systems which may allow for a >>> smooth interpolant across the arbitrary convex polygons without the >>> laplacian solve (I am suggesting you can combine this with some of the >>> principles of the above paper): >>> >>> http://morphoxx.googlecode.com/svn/trunk/Biblio/Mean%20Value%20Coordinates%20for%20Arbitrary%20Planar%20Polygons.pdf >>> >>> Not sure if there is quality issues with it that I don't know about. You >>> probably don't want to be doing novel research on a tight deadline. >>> >>> >>> >>>> On Thu, Dec 12, 2013 at 8:55 AM, Alok Gandhi <[email protected]> >>>> wrote: >>>> Thanks Ben. That is some good info. I was thinking more along >>>> implementing the Harmonic Coordinates approach. I think Pixar had some >>>> papers on it. >>>> >>>> Sent from my iPhone >>>> >>>>> On Dec 11, 2013, at 10:50 PM, Ben Houston <[email protected]> wrote: >>>>> >>>>> My knowledge is out of date, but off the top of my head.... >>>>> >>>>> Cage deformers are often written using a cubic interpolant rather than >>>>> affine ones. If you use a grid cage you can use Bezier Volumes, which >>>>> are just a generalization of >>>>> https://en.wikipedia.org/wiki/B%C3%A9zier_surface. If you are using a >>>>> regular grid, you can just take 3D coordinates relative to each grid. If >>>>> you use a tetrahedral mesh, you can use generalization of the Cubic >>>>> Triangle for deformation: >>>>> https://en.wikipedia.org/wiki/B%C3%A9zier_triangle and then you need to >>>>> use barycentric coordinates to get a relative spatial relationship. >>>>> >>>>> So I think yes, barycentric coordinates within a space filling >>>>> discretization of space, either a grid or a tetrahedralization with a >>>>> cubic interpolate as you start to deform them. >>>>> >>>>> I implemented the grid-based deformation with cubic volumes and got this >>>>> result: >>>>> >>>>> http://www.exocortex.org/ben_software/hd-ffd.zip >>>>> >>>>> I have also implemented the tetrahedral-based discretization with >>>>> Christopher Batty to deform a high resolution object to follow the path >>>>> of a low resolution object to really good success. The only issue is >>>>> that tetrahedral meshes suck to create and maintain efficiently. It is >>>>> the bunny getting crushed in the gears at the end of this video -- the >>>>> actual simulation bunny was super low res, but we uprezed it for >>>>> rendering: http://vimeo.com/874168 >>>>> >>>>> Best regards, >>>>> -ben >>>>> >>>>> >>>>> >>>>>> On Wed, Dec 11, 2013 at 5:09 PM, Alok Gandhi <[email protected]> >>>>>> wrote: >>>>>> Hi All, >>>>>> >>>>>> Very soon, I am starting on my own generic custom cage deformer. A mix >>>>>> of C++/Cython/Python. >>>>>> >>>>>> I am thinking of implementing fast calculations on barycentric >>>>>> coordinates with affine transformations. I have some good papers (in my >>>>>> treasure trove but haven't checked it yet). >>>>>> >>>>>> Anyone suggest a different approach other than barycentring coordinates. >>>>>> >>>>>> The reason I will be writing this is for (proof of concept / prototype >>>>>> for now) is to be able to get point cache data from a low res geometry >>>>>> and then use this outside of an DCC to convert to high res deformations. >>>>>> >>>>>> This ways existing animation pipelines which have to rely on switching >>>>>> to higher resolutions before caching out do not have to do so. Simply >>>>>> export out point caches (alembic, pc2, mdd, bgeo, icecache etc.) and >>>>>> then apply this to a high res point data outside of any DCC as post >>>>>> process, even on farms from command line for example. >>>>>> >>>>>> -- >>>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> Best regards, >>>>> Ben Houston >>>>> Voice: 613-762-4113 Skype: ben.exocortex Twitter: @exocortexcom >>>>> http://Clara.io - Professional-Grade WebGL-based 3D Content Creation >>> >>> >>> >>> -- >>> Best regards, >>> Ben Houston >>> Voice: 613-762-4113 Skype: ben.exocortex Twitter: @exocortexcom >>> http://Clara.io - Professional-Grade WebGL-based 3D Content Creation >> >> >> >> -- >> Best regards, >> Ben Houston >> Voice: 613-762-4113 Skype: ben.exocortex Twitter: @exocortexcom >> http://Clara.io - Professional-Grade WebGL-based 3D Content Creation >
