Intersecting Rays against Nurbs

Hi,

i am primarily a rhino plugin developer and i would like now to produce a novel raytracing and analysis engine with the help of Grasshopper for scientific & industrial purposes.

Today, i was wondering which algorithmic is actually used by ray/surface intersection component. The answer may probably rely on rhino's rayshooter implementation, but i found it was very slow.

However, there are a number of fast and robust techniques for direct Nurbs raytracing (see for instance Bézier Clipping and/or Newton-Raphson's iterations in Efremov's paper "Robust and Numerically Stable Bézier Clipping Method for Ray Tracing" at http://www.cin.ufpe.br/~sbm/CGartigos/p127-efremov.pdf).

Many hot applications require raytracing and grasshopper would gain at implementing fast and accurate ray/surface component.

Could you give some details you could tell about ray/nurbs intersection implementation.

Thanks in advance.

PS : one more time, congrat for this awesome tool called GH :)

Replies to This Discussion

Permalink Reply by David Rutten on December 3, 2013 at 2:17am

Hi Sebastien,

GH indeed just uses the Rhino ray-shooter, however GH only has a Mesh|Ray intersection component, there is no Nurbs|Ray intersector. The components which compute intersections between infinite lines and surfaces/breps in fact just extend the line throughout the boundingbox, then they perform a Curve|Brep intersection.

David Rutten

david@mcneel.com

Permalink Reply by Sebastien on December 3, 2013 at 2:36am

Hi David,

thanks for reply, may be you would like to have a better support for raytracing in GH framework ?

I would llike to implement such a component that allows for fast direct surface / ray (and lines too) intersections. Many people playing with (tons of) rays in their applications would enjoy this.

The idea behind this is of course to use Bezier Clipping algorithm and newton descent iteration as an option.

Please let me know your interest.

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