Closest distance from curve to surface

[damselindistress]

any suggestion how i should calculate the shortest/closest distance between a curve and the nurbs surface?

say in a scene with a few nurbs object, how do i calculate the closest distance from the curve to each of the nurbs objects?

any help will be really appreciated, please! any suggestion welcome! thanks!!!!!!!!

[queequeg]

Do you want to compute the points on the curve/surfaces or are these points given/fixed?

You could get an approximation by geometryConstraining a locator to the curve, and aimConstraining it to one of the surfaces. Then you use the distance tool to measure the distance between the locator and the surface. If you need a better approximation, geometryConstrain a second locator to the surface and aimConstrain this second locator to the first. Apply the distance tool to the locators.

If you need the exact solution, learn differential calculus.

[damselindistress]

I want to compute the points on the curve. I do not want any particular fixed points. So if I use the geometryConstraining method, I already fix a particular point on the curve, don't I? But this point may be closest to nurbs-object-#1 but not the closest point to nurbs-object-#2 in the scene.

What I want is to have this shortest distance between the curve and each nurbs object, so that if it is smaller than a certain value, it will do something else.

Would the suggested method still work? I'd welcome and appreciate any suggestion or advice. Thank you very much!!! Appreciated!

[queequeg]

LOL trying it out is just a few clicks away!

geometryConstraining means that the locator stays on the curve, no matter what... Ah well, just try it out.

Oh, and no, it won't always work. It depends on the curve you have. Try and see. If it doesn't work, learn calculus or forget it.

What you want to do is determine the global minimum of a function in multiple variables. That is a nontrivial problem, since the only way to do this is to determine all the local minima, and, depending on the complexity of the curve and surfaces, that can be quite computing intersive.

Anyway, may I ask what you want to do with that? Maybe there's another solution.

[damselindistress]

This is what I'm trying to do:

In a scene with several patches of fur-covered nurbs object, when a ball moves through the scene following the curve path, I want to know which fur objects will have their fur affected by the movement of the ball due to their close proximity. That is why I want to know how to calculate the closest distance between the fur surface and any curve in the scene.

Any other idea how I can approach this problem? Or better suggestion to what I proposed? Thanks for any advice. Appreciated!

[queequeg]

Ah, ok, this should be doable. If you only want to know which patch is closest, then you only have to use one distance tool for each patch, to measure the distance to the ball. In that case it's only a matter of transform nodes, and is not NURBS specific in any way.

To find out the closest location on the closest surface, read the next post. ;;

[joojaa]

Id rather use closest point on surface =)

[queequeg]

LOL that would obviously be the much better advice. Didn't know that one, thx.