Speckle Impl Autocad Civil3d

speckle-impl-autocad-civil3d

Quick Reference

Supported Versions

Data Schema Hierarchy

AutoCAD:   File > Layer > Objects
Civil 3D:  File > Layer > Objects (inherits AutoCAD structure)

Publishable Content (AutoCAD)

Publishable Content (Civil 3D: Additional)

Critical Warnings

NEVER expect 3D solids to survive the Speckle pipeline as solids. AutoCAD and Civil 3D connectors ALWAYS convert solids to Mesh geometry during publishing. This conversion is irreversible. If downstream workflows require solid geometry (boolean operations, mass properties from solids), this pipeline is NOT suitable.

NEVER assume XData or Extension Dictionary data transfers automatically to the receiving application. This data appears in the Speckle properties field and is visible in the web viewer, but the receiving connector may NOT attach it to loaded objects.

NEVER expect coordinate system alignment options in Civil 3D. Unlike the Revit connector, Civil 3D has NO reference point publishing configuration. Objects publish using the drawing's World Coordinate System.

NEVER rely on color display without verifying viewer settings. AutoCAD/Civil 3D colors require Shaded view mode in the Speckle viewer to display correctly.

AutoCAD Object Model in Speckle

Identity Mapping

The applicationId maps to the AutoCAD Handle — a persistent hexadecimal identifier that remains stable across saves and edits. ALWAYS use applicationId for cross-version object tracking, NEVER use id.

Geometry Objects

AutoCAD geometry publishes as Speckle Geometry Objects — pure geometric primitives without semantic metadata:

• Point, Line, Arc, Circle, Ellipse
• Polyline, Polycurve (complex curves)
• Mesh (including converted solids)
• Hatch (pattern fills with boundary geometry)
• Text (single-line and multi-line)

Block Architecture

AutoCAD blocks map to Speckle's Instance + Definition pattern:

Block Reference (Insert) → Instance Object
  - definitionId: references a Definition proxy
  - transform: 4x4 matrix (position, rotation, scale)

Block Definition → Definition Proxy (at Root Collection level)
  - name: block name
  - value: definition geometry (displayValue)
  - objects: array of applicationId strings for all instances

ALWAYS expect blocks to decompose into this two-part structure. A single Definition proxy serves all Instance objects that reference the same block.

Layer Mapping

AutoCAD layers map directly to Speckle Collections:

Drawing.dwg
└── Layer: "A-WALL"
    ├── Line object (applicationId: "1A3")
    └── Polyline object (applicationId: "1B7")
└── Layer: "S-BEAM"
    └── Mesh object (applicationId: "2C4")

Layer properties (color, linetype) are NOT preserved as layer metadata. Object-level color assignments transfer via Color proxies.

Custom Properties (XData and Extension Dictionaries)

XData and Extension Dictionaries appear in the properties dictionary of each object:

{
  "speckle_type": "Objects.Geometry.Line",
  "applicationId": "1A3F",
  "properties": {
    "ExtensionDictionary": {
      "MyCustomDict": {
        "ProjectCode": "P-2024-001",
        "Phase": "Construction"
      }
    },
    "XData": {
      "APPNAME": {
        "values": ["custom_data_1", 42.5]
      }
    }
  }
}

ALWAYS check the properties field for custom data. Extension Dictionaries are nested by dictionary name; XData is nested by registered application name.

Proxy Types (AutoCAD)

Civil 3D Object Model in Speckle

Civil3dObject

Civil3dObject extends DataObject with infrastructure-specific fields:

{
  "speckle_type": "Objects.Data.DataObject:Objects.Data.Civil3dObject",
  "applicationId": "3F7A",
  "type": "Alignment",
  "displayValue": [
    { "speckle_type": "Objects.Geometry.Mesh", "...": "visual representation" }
  ],
  "baseCurves": [
    { "speckle_type": "Objects.Geometry.Polycurve", "...": "fundamental curve" }
  ],
  "properties": {
    "PropertySets": {
      "Alignment Properties": {
        "StartStation": 0.0,
        "EndStation": 1250.0,
        "Length": 1250.0
      }
    },
    "PartData": { "...": "entity-specific data" }
  }
}

Key Distinction: displayValue vs. baseCurves

ALWAYS use baseCurves when you need the geometric definition of an alignment, profile, or featureline. The displayValue contains the visual representation (a mesh for most Civil 3D objects), which is NOT the same as the design curve.

Civil 3D Entity Types

Corridor Data Structure

Corridors are complex Civil 3D objects. In Speckle, corridor data includes:

• Featureline geometry for each corridor code point
• Corridor codes identifying each featureline's role
• Region definitions

ALWAYS expect corridor featurelines to be accessed through properties, NOT as direct child objects. Corridors do NOT contain nested Civil3dObjects.

Property Sets

Civil 3D Property Sets publish as structured dictionaries inside properties:

{
  "properties": {
    "PropertySets": {
      "Pipe Properties": {
        "InnerDiameter": 0.3,
        "OuterDiameter": 0.35,
        "Material": "PVC",
        "SlopePercent": 2.0
      }
    }
  }
}

Each Property Set is keyed by its definition name. Values include strings, numbers, and booleans.

PropertySetDefinition Proxy (Civil 3D Only)

Civil 3D adds a fifth proxy type not present in standard AutoCAD:

This proxy stores the schema of each Property Set — field names, data types, default values. It references objects that use the property set via the standard objects array of applicationId strings.

Proxy Types (Civil 3D: Full Set)

Publishing Workflow

AutoCAD Publishing Steps

1. Open the Speckle connector panel in AutoCAD
2. Select a Speckle project and model
3. Choose objects to publish (manual selection or all visible)
4. Click Publish — all selected objects convert to Speckle schema
5. Layers become Collections; blocks split into Instance + Definition

Civil 3D Publishing Steps

1. Same UI as AutoCAD (Civil 3D connector extends AutoCAD connector)
2. Civil 3D entities automatically convert to Civil3dObject type
3. Property Sets, Part Data, and class-specific properties captured automatically
4. Standard AutoCAD objects (lines, blocks) publish as standard Geometry Objects

What Publishes Automatically

• All geometry with layer assignment
• Colors (object-level and layer-level via proxy)
• Render materials
• XData and Extension Dictionaries
• Block references as Instance + Definition
• Civil 3D: Property Sets, Part Data, network specifications, surface statistics

What Does NOT Publish

• Layer properties (linetype, lineweight as layer metadata)
• Layout/paper space content (model space only)
• OLE objects
• External references (xrefs) as linked data
• Coordinate system/reference point configuration (Civil 3D limitation)

Loading (Receiving) Workflow

Loading Behavior

Layer Flattening on Load

When loading into AutoCAD/Civil 3D, the layer structure is FLATTENED to match what the Speckle web viewer displays. Nested Collection hierarchies from other connectors (e.g., Revit's Level > Category > Type) collapse into a flat layer structure.

Selection Set

All loaded objects are placed into a dedicated Selection Set. This enables easy selection of all Speckle-loaded objects without manual picking. ALWAYS use this Selection Set for post-load operations.

Cross-Application Exchange

AutoCAD/Civil 3D as Publisher

AutoCAD/Civil 3D as Receiver

Asymmetric Fidelity

Publishing from AutoCAD/Civil 3D preserves MORE information than loading into it. A Civil 3D alignment with Property Sets, station data, and profile geometry publishes as a rich Civil3dObject. When loaded into Rhino, it becomes geometry with properties as user strings — the native Civil 3D semantics are lost. When loaded back into Civil 3D, it becomes standard geometry, NOT a native alignment.

Reference Links

• references/methods.md — Object schemas, property structures, proxy definitions for AutoCAD and Civil 3D
• references/examples.md — Working data examples for publish, load, and cross-application workflows
• references/anti-patterns.md — What NOT to do, with explanations

Official Sources

• https://docs.speckle.systems/connectors/autocad.md
• https://docs.speckle.systems/connectors/civil3d.md
• https://docs.speckle.systems/developers/data-schema/connectors/autocad-schema.md
• https://docs.speckle.systems/developers/data-schema/connectors/civil3d-schema.md
• https://docs.speckle.systems/developers/data-schema/object-schema.md
• https://docs.speckle.systems/developers/data-schema/proxy-schema.md