snap radius to join two splines?

[martinvk]

How close do two spline points have to be before they join?
Can this snap distance be user adjusted?

When I have two tracks on the surface, they join pretty easily. Even when they are not very close. In fact sometimes they are too eager to join and I have to use Shift to stop them.
When they are both the same distance underground, they are reluctant to join unless they are right on top of each other and even then it sometimes takes a few attempts.

 

[pware]

How close do two spline points have to be before they join?

The answer depends on how close you zoom in.

I did a few basic experiments and came up with the following somewhat crude measurements.

1. When a single baseboard fills the screen from top to bottom (i.e. ~720 top to bottom*) the "snap distance", where the two splines will snap together, is just under 10m
2 Top to bottom distance ~300m the "snap distance" is about 7-8m
3 Top to bottom distance ~100m the "snap distance" is about 5m
4 Top to bottom distance ~50m the "snap distance" is about 2m
5 Top to bottom distance ~10m the "snap distance" is about 0.25m

* this may vary with your screen resolution setting

As far as I know, this setting cannot be user adjusted.

 

[martinvk]

I get similar results in a windowed environment when the splines are on the surface.

When they are 8m underground and I look at a steep but not vertical angle, even when they appear to be coincident, they rarely auto-join. Only if I look straight down and place the cursor cross hair directly over one spline, and I move the other spline to almost touching, will they auto-join.

Will have to test different depths to see if it is proportional.
[test]
It seems the snap distance is determined by the viewpoint to surface distance and not the viewpoint to object distance underground. By backing off further from the object, the snap increases and appears more normal