Report of Clashes with all Segments

Model Reference Manual

Clash Detection : Report of Clashes with all Segments

Report of Clashes with all Segments

By default, a single position is reported for a clash between significant elements. It is possible to arrange for a clash position report for each clashed component or segment of an element using:

Clash detection reverts back to single clash reporting for an element using:

SEGMENTS ON is designed to detect distinct and multiple segment clashes between two elements when one of the elements is a path or a spine based element such as a GENSEC, CABLE, CTWALL, WALL etc. It also breaks catalogue items down into component primitives or segments and report clashes with them. In each case the MIDPOINT of the clash volume with the specific segment is reported, irrespective of the MIDPOINT option setting.

In contrast, linear elements like pipes and ducts which are decomposed into distinct individual elements and tubes are not treated in this way. Normal clash detection identifies the subsidiary element that is being clashed and reports them as such between the checked element and the clashing piping component. For path-like elements this is not possible. The individual distinct clashes with subsidiary segments (geometrical primitives) are all reported as clashes with the owning element (GENSEC, STRFLT etc).

The process does NOT detect multiple clashes between individual segments (primitives). The clash position reported when multiple clash regions exist is misleading. The midpoint of the box that encloses ALL the clashes is reported, and this is very likely to bear little relation to the position of any of the individual clashes. The user should be aware of this. Concave segments can provoke this situation; they are not common but do include the torus and solids of revolution. They are found as pipe bends and arc sections in gensecs, walls, and cables etc.

Details of the SEGMENTS option

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This only controls detection of CLASHES. Positions of TOUCHES and CLEARANCES are unaffected by the SEGMENTS option when a single, initial or midpoint position is reported.

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The option takes precedence over the MIDPOINT option (for clashes) when active, MIDPOINT remains active for touches and clearances, and becomes active again for clashes when SEGMENTS is switched OFF

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Multiple clashes are saved to working files on SAVE and the multiple option is set on RESTORE of the data along with the other active options.

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Approvals processing is unaffected by the SEGMENTS option. This remains a significant element to a significant element control. Individual clashes are not selectively approved.

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This options allows detailed study of clashes with path driven elements and can aid positioning and hole management.

A clash is first detected by the checking process and if one is found then segment clashes are investigated. The process employed is:

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The significant obstruction and test elements are decomposed into individual primitives

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this includes individual curves or segments in a cable, wall, or gensec.

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primitives composing catalogue items.

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All paired combinations of obstruction and check primitives are considered in turn.

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Each combination can report a SINGLE clash between them, together with its enclosing box.

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The set of clashes obtained are processed to identify distinct clash regions:

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Clash boxes that overlap or abut others occur at the junction of primitives or gensec/cable segments.

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Clashes which overlap with MORE than one other clash box occur when a box encloses more than one clash region. These are ignored; the overlapping clashes are sufficient to identify the clash regions.

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Each pair of overlapping clash boxes are combined and report a better estimate of the position of the clash region at the junction of the two primitives.

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The remaining non-overlapped clash boxes are reported as clashes.

Limitations of this algorithm

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Multiple clashes solely between two individual primitives are NOT be identified. For example only one clash is reported if a straight SCTN penetrates through a pipe BEND, or passes through a TORUS, or a curved segment of a wall, twice.

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In general primitive clashes that overlap or abut other clashes with other segments are ignored (as occurs at a segment join) and this normally makes sure that each clash volume is only reported once. However some duplicate reports can occur.

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The reported positions of the clashes are approximate and, like the midpoint positions, are the centroid of the box enclosing the clash regions. For unique clashes with primitives this is generally be close to the clash centre. However if the primitive is curved and thin it may itself not pass near the box centre and in these cases the position will be more approximate.

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For clashes at primitive junctions then the reported position may be the centre of the clash box with just one of the primitives, or the centre of the whole clash region depending on the primitives involved.

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Up to 10 clashes may be reported. More than that are ignored. It is possible to artificially provoke many clashes of primitives if, say a GENSEC with many sections is copied and the copy is overlayed and clashed with the original. However, this scenario is expected to be extremely rare and is therefore not covered.

Command Syntax:

>-- SEGMENTS --+-- ON ---.

Q CLASH SEGMENTS

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