clash-detection

Clash Detection & Coordination

Perform clash detection for:

"$ARGUMENTS"

Before scripting

Clarify:

1. Which two disciplines are you checking? (e.g. structural columns vs MEP ducts)
2. How should clashes be reported? (list of IDs, CSV export, isolate in view?)
3. Minimum clash volume? Default threshold is very small (1e-6 ft³) to catch all contacts.

Note: for large models, Boolean intersection on every element pair is slow. Recommend running on a specific level or workset, or using Navisworks for production-scale clash detection.

Clash detection script

Read-only — no model modifications.

import clr
clr.AddReference('RevitServices')
from RevitServices.Persistence import DocumentManager
clr.AddReference('RevitAPI')
from Autodesk.Revit.DB import *

doc = DocumentManager.Instance.CurrentDBDocument

# ── Define the two element sets to check ────────────────────────────────────
# Modify these categories for your discipline combination:
set_a = list(FilteredElementCollector(doc)
             .OfCategory(BuiltInCategory.OST_StructuralColumns)
             .WhereElementIsNotElementType()
             .ToElements())

set_b = list(FilteredElementCollector(doc)
             .OfCategory(BuiltInCategory.OST_DuctCurves)
             .WhereElementIsNotElementType()
             .ToElements())

# ── Helper: extract solid geometry from an element ──────────────────────────
def get_solid(element):
    opts = Options()
    opts.ComputeReferences = False
    opts.DetailLevel = ViewDetailLevel.Fine
    geo = element.get_Geometry(opts)
    if geo is None:
        return None
    for obj in geo:
        if isinstance(obj, Solid) and obj.Volume > 1e-9:
            return obj
        if isinstance(obj, GeometryInstance):
            for sub in obj.GetInstanceGeometry():
                if isinstance(sub, Solid) and sub.Volume > 1e-9:
                    return sub
    return None

# ── Run clash detection ──────────────────────────────────────────────────────
clashes = []

try:
    for el_a in set_a:
        solid_a = get_solid(el_a)
        if solid_a is None:
            continue

        # Get type name once per el_a (minor optimisation)
        type_id_a = el_a.GetTypeId()
        type_name_a = (doc.GetElement(type_id_a).Name
                       if type_id_a != ElementId.InvalidElementId else 'N/A')

        for el_b in set_b:
            solid_b = get_solid(el_b)
            if solid_b is None:
                continue
            try:
                intersection = BooleanOperationsUtils.ExecuteBooleanOperation(
                    solid_a, solid_b, BooleanOperationsType.Intersect)

                if intersection and intersection.Volume > 1e-6:
                    type_id_b = el_b.GetTypeId()
                    type_name_b = (doc.GetElement(type_id_b).Name
                                   if type_id_b != ElementId.InvalidElementId else 'N/A')
                    clashes.append({
                        'Element A ID':   el_a.Id.IntegerValue,
                        'Element A Type': type_name_a,
                        'Element B ID':   el_b.Id.IntegerValue,
                        'Element B Type': type_name_b,
                        'Clash Volume (ft3)': round(intersection.Volume, 6),
                        'Clash Volume (cm3)': round(intersection.Volume * 28316.8, 2),
                    })
            except:
                # Boolean operation failed — elements may share a face (contact, not clash)
                pass

    OUT = [len(clashes), clashes]

except Exception as e:
    import traceback
    OUT = 'ERROR: ' + str(e) + '\n' + traceback.format_exc()