Jump to content

Geometry 3D Rotation - Failure to Grok


Recommended Posts

Wanting to rotate an arbitrary 3D point, cords X,Y,Z relative to XYZ location 0,0,0 in a 3D system.

But all I find is Math/Geometry/3D Rot (direct and euler) which both take ARRAYS for their input, and a 3X3 ARRAY for it's command. I do not grok this concept at all. What's going on? How can I use it instead to deal with a single point (anywhere) relative to the system origin?

Problem relates to a calculator I have built for the design of log-periodic antennas. The antenna consists of wires, paired as XYZ_from and XYZ_to with also a subunit 'segments' for each, thus a 4xN array of (X,Y,Z,Segs) of arbitrary length. First wire is always on the origin. So I'm wanting to perform pitch/roll/yaw on this antenna from point 0,0,0. But do it by running my coordinates X,Y,Z for each wire-end, one set at a time, through a transformation filter. And the whole 3x3 matrix makes no sense to me. Sorry, I'm 30 years out of college. This is a hobby project for a calculator I'll give away free. Can someone clue me in?

Link to comment
3 hours ago, Gan Uesli Starling said:

all I find is Math/Geometry/3D Rot (direct and euler) which both take ARRAYS for their input, and a 3X3 ARRAY for it's command... How can I use it instead to deal with a single point (anywhere) relative to the system origin?

I presume you mean the 3D Cartesian Coordinate Rotation VIs. The NI documentation has a decent description of what they do: https://zone.ni.com/reference/en-XX/help/371361R-01/gmath/3d_cartesian_coordinate_rotation_euler/

These are polymorphic VIs. By default, they take an array of coordinates. If you just want to rotate a single point, select the "Scalar" version of the VI (Put the subVI on your block diagram, then Right-click > Visible Items > Polymorphic VI Selector)

 

3 hours ago, Gan Uesli Starling said:

a 3X3 ARRAY for it's command. I do not grok this concept at all. What's going on?....

And the whole 3x3 matrix makes no sense to me.

The 3x3 matrix is the transformation matrix, which is a concept described in linear algebra. There are different types of transformations: Translation, rotation, shearing, scaling, etc.

In a nutshell: Think of your 3D point-coordinates as a 3x1 matrix (also called a column vector). If you multiply a column vector by a 3x3 matrix, you will get a new column vector. That new vector will contain your "transformed" point-coordinates.

Edited by JKSH
  • Thanks 1
Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Unfortunately, your content contains terms that we do not allow. Please edit your content to remove the highlighted words below.
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.