[Bf-committers] Mesh curvature estimation

pete larabell xgl.asyliax at gmail.com
Thu Dec 1 21:08:00 CET 2011

I dont think the MIQ project got very far, since I've offered to
implement this once my work on compositor / mask editor is done, and
my offer was generally greeted with much happiness that "someone" was
going to do this...

noone even mentioned to me that anyone did a gsoc on it... so im
guessing it didn't go TOO far... but maybe I'm wrong... idk.

On Mon, Nov 28, 2011 at 6:01 AM, Vincent Nivoliers
<vincent.nivoliers at loria.fr> wrote:
> [2011-11-27 19:38:53 -0500] Nicholas Bishop:
>> Hi all,
>> A few times I've run into algorithms that require principal curvatures
>> [1] as inputs. My cursory examination of the Blender source (basically
>> just grepping for "curvature") didn't turn up any code for this, so I
>> ported the (GPLv2) curvature code from the trimesh2 lib [2] to
>> Blender. That code is based on the paper "Estimating Curvatures and
>> Their Derivatives on Triangle Meshes" [3]. Dunno if this is useful to
>> anyone else, but I've pushed a Blender branch [4] containing the
>> curvature calculation (in blenlib/intern/curvature.c), as well as a
>> test modifier that displays the curvature vectors.
>> Screenshot with Suzanne: http://www.pasteall.org/pic/show.php?id=21557
>> Notes:
>> The original code was in C++; I converted it to C and switched the
>> math stuff over to blenlib and the types to MVert/MFace/etc. The
>> per-vertex output is the two principal curvatures and two direction
>> vectors. I haven't updated the code to handle quads yet, it'll
>> assert() if it encounters a non-triangle face. I've only just gotten
>> this working, so there are definitely bugs in it yet. :)
>> Thanks,
>> -Nicholas
>> [1] http://en.wikipedia.org/wiki/Principal_curvature
>> [2] http://gfx.cs.princeton.edu/proj/trimesh2/
>> [3] http://gfx.cs.princeton.edu/pubs/_2004_ECA/
>> [4] https://gitorious.org/~nicholasbishop/blenderprojects/nicholasbishop-blender/commits/tri-curvature
> Hi,
> There was a gsoc project last year [1] about the implementation of mixed
> integer quadrangulationsa [2] into blender. I don't know where this
> project lies now, but I believe this code uses a curvature estimator to
> generate a direction field on the surface.
> Thanks for this work,
> -- Vincent
> [1] http://code.google.com/p/google-summer-of-code-2010-blender/
> [2] http://www.graphics.rwth-aachen.de/uploads/media/bommes_zimmer_2009_siggraph_01.pdf
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