Detect Zero length entities tolerance?

[Husky]

Hi,

I'm right now trying to understand how the "Detect Zero length entities" works regarding to the tolerance. My impression till now was that if I give the tool the tolerance of (e.g.) 0.005 it will select everything what is less than 0.005. For lines it works like expected - but it doesn't works at circles. I have the feeling that it works on circles like "equal or less" to the given value.

Husky-2015.12.04-02.png (27.32 KiB) Viewed 3605 times

Is that correct and if yes - why is that so?

Detect Zero length tolerance.dxf

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[andrew]

The condition is always size <= tolerance, for all entities.

Unfortunately, computers cannot store floating point numbers accurately enough to make such comparisons reliable.

If you wish to select everything that is 0.005 or smaller, enter a tolerance that is larger than 0.005 (e.g. 0.0051 or 0.00500001).

[Husky]

Unfortunately, computers cannot store floating point numbers accurately enough to make such comparisons reliable.

Thanks Andrew - I wasn't aware of that.

If you wish to select everything that is 0.005 or smaller, enter a tolerance that is larger than 0.005 (e.g. 0.0051 or 0.00500001).

Ok - that isn't really satisfying to me but I understand that we have to deal with this fact. But may I ask you one more question: I've never noticed this problem with the "Selection Filter Tool". Is it different working - except that it is only searching for one Entity Typ?

[andrew]

But may I ask you one more question: I've never noticed this problem with the "Selection Filter Tool". Is it different working - except that it is only searching for one Entity Typ?

The selection filter would also have this problem and since a query with operator "= (equals)" would simply never yield any results at all, the tool deals with these tolerance issues internally by using a fuzzy comparison.

When using the zero length detection tool on the other hand, a tolerance is entered and not a target value. It would be possible but possibly somewhat confusing to have another internal tolerance applied to the entered tolerance. I never really thought of the zero length detection tolerance as a precise value but rather an approximate threshold to make sure only very tiny entities are selected / deleted.

If you need a precise threshold the selection filter seems better suited indeed.