# How to represent an edge in 3D coordinate systems?

This topic is 2174 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

## Recommended Posts

Vector v1;

Vector v2;

Edge e = v2 - v1;

As this edge is oriented freely in 3D space, How do you know which x,y,z in these vectors is the major axis?

Thanks

Jack

##### Share on other sites

Do you mean which axis out of x, y and z has the longest projection onto it? It would be the coordinate axis with the largest magnitude (absolute value) out of e.x, e.y and e.z.

##### Share on other sites

Do you mean which axis out of x, y and z has the longest projection onto it? It would be the coordinate axis with the largest magnitude (absolute value) out of e.x, e.y and e.z.

Thanks, that looks simple enough... I am just silly.

Jack

##### Share on other sites

Would there be a case where the projections on all three axis have the same magnitude?

How should I decide if this happens?

Thanks

Jack

Edited by lucky6969b

##### Share on other sites

Of course such a case exists. You just need two vectors whose difference is the same along all axes. What happens then is up to you to decide, we don't know anything about your goals here.

##### Share on other sites

Pick one. You can either pick the same axis all the time, cycle through the axes, or pick it at random.

• 12
• 18
• 29
• 11
• 24