http://processing.org/reference/PVector_normalize_.html

usually works, beware though that positions in space should not be normalised, normalise only works for directions.
If you want to use the positions to calculate direction first you have to figure out relative to what other point you want a directional vector.

e.g
point x,y,z    cloudcentre a,b,c

then the normal vector should be taken of vector
(x-a, y-b, z-c)

consequently if you want the directional vector accoring to Origin (0,0,0) then you can use the positional vector.

If you want to calculate the normalised vector yourself for some reason:

Calculate legth of vector: len(x-a, y-b, z-c)
You can use Pythagoras for this, he wont mind
and then devide your coordinate points by this value (x/ len(x-a, y-b, z-c), y/ len(x-a, y-b, z-c), z/ len(x-a, y-b, z-c))

good luck

Hey  janjacobsv,

the link seems to open to the front page.
In any case a normal vector is also a normalised vector pointing in the direction of the object. Unless it is about surfaces then it is usually the normalised directional vector perpendicular to the surface.

A single point cannot have a normal vector but a surface can.

If you have three points on a surface (p0,p1,p2) then the surface normal vector at position p0 is the cross product of (p1-p0) and (p2-p0).

In Processing using the PVector class then the code below shows how to create the normal without changing p0, p1 or p2

1. PVector p0, p1, p2, n;
2. 
   
3. p0 = new PVector(0,0,0);
4. p1 = new PVector(1,0,0);
5. p2 = new PVector(0,1,0);
6. 
   
7. n = PVector.cross(PVector.sub(p1,p0,null), PVector.sub(p2, p0,null),null);
8. n.normalize();
9. println(n);

> the link seems to open to the front page.

yeah, it's odd. my url had a space at the end which was confusing it.


yes, you would need (at least) triangles to get normals. could you choose 2 nearest neighbours and use those?

I want to define several planes inside a point cloud and then distinguish the floor plane. Sorry for the wrong information I updated the link with an image also. I have to manage 307200 points and I don t know how to set a loop in order do this calculations for every point.