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pipes intersect, yet none of the triangles that define their geometry do
and so this clash would be missed using the standard Hard clash test
type. However, choosing Hard (Conservative) reports all pairs of items,
which might clash. This may give false positives in the results, but it is a
more thorough and safer clash detection method.
Severity
For hard clashes, the severity of a clash depends on the intersection of
the two items intersecting. Hard clashes are recorded as a negative
distance. The more negative the distance, the more severe the clash.
Hard clash severity depends on whether the Conservative or Normal
Intersection Method has been applied (see Intersection Method for
more details on this). If Normal, the greatest penetration between a pair
of triangles is measured. If Conservative, the greatest penetration of
space around one item into the space around another is measured.
For clearance clashes, the severity depends on how close one item
invades the distance required around the second. For example, an item
coming within 3mm is more severe than an item coming within 5mm of
the other.
For duplicate clashes, the severity depends on how close one item is to
the other. When the distance between them is zero, it is more likely that
this is duplicate geometry, where as items that are further apart are more
likely to be different objects and therefore have a lesser severity.
Tolerance
The Tolerance controls the severity of the clashes reported and the
ability to filter out negligible clashes, which can be assumed to be
worked around on site. Tolerance is used for Hard, Clearance and
Duplicate types of clash test. Any clash found that is within this tolerance
will be reported, whereas clashes outside of this tolerance will be
ignored. So for Hard clashes, a clash with a severity of between zero
and the tolerance value will be ignored, whereas for Clearance clashes,
a clash with a severity of more than the tolerance value will be ignored
as it is further away than the distance required. Similarly, a Duplicate
clash with a severity of more than the tolerance value will be ignored as it
is likely to be a seperate, yet identical piece of geometry.
Glossary
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