Find Closest Point/s On Closed Surface

Hi All

After trying over 24hrs of trying to crack a code i have run out of workflows so asking here...

Does anyone have any ideas on how to find the closest point/s on a closed surface from a defined point on that surface. I have a working code for an open surface but yet to find a way to rebuild the logic so it work on a closed surface.

In the attached the code the surface is reparameterized surface but this is only beacuse the test is using an MD Slider

Thank

Matt

Attachments:

closest point on open surface by UV.ghx, 91 KB

Replies to This Discussion

Permalink Reply by Giulio Piacentino on January 16, 2011 at 11:52am

My pleasure. Yes, maybe the last two examples are faster.

Permalink Reply by Giulio Piacentino on January 16, 2011 at 11:41am

Maybe you prefer one of these other two methods, based one on taxicab distance and the other on wrapped UV coordinates distance.

method 4: UV taxi	method 5: UV wrap
jumps in U and V	jumps in U and V
grid distance on U and V taken separately	distance in U and V coordinates
similar to the first example	similar to the first example

Attachments:

closestpointonopensurfacebyTaxi.ghx, 124 KB
closestpointonopensurfacebyUVwrap.ghx, 126 KB

Permalink Reply by Matt Gaydon on January 16, 2011 at 12:10pm

Wow... Both seem Perfect and rather quicker than Geodesic. How similar are these 2 methods above as the Function seems to be quite similar.

In the 5th method all i need to remove from the expression is R≥ to get the distance between points. then cull these numbers after.

I understand they work great on a standard torus but as i am yet to full understand the expressions i though i would ask would they work on a "organic" Torus..(One i have deformed a re-shaped in T-splines though still a single NURBS Surface and still containing closed seems

Some think like this.

Thanks for all Your Help

Matt

Permalink Reply by Giulio Piacentino on January 16, 2011 at 12:31pm

> In the 5th method all i need to remove from the expression is R≥ to get the distance between points. then cull these numbers after.

We do not get the real-world distances there, as we are measuring UVs. We get the distance calculated from UV-to-UV, and measured either in "aerial" mode or "like in a taxi ride" (see link above for a picture).