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The Civil 3D connector exports civil engineering entities from Autodesk Civil 3D, preserving layer organization and property set data.

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Hierarchy

Civil 3D models are organized by File and Layer: 
Root Collection
├── Civil 3D File
│   └── Layer
│       ├── Civil3dObject
│       ├── Geometry (standalone)
│       └── Instance
├── Proxies: RenderMaterial[]
├── Proxies: Color[]
├── Proxies: Group[]
├── Proxies: Definition[]
└── Proxies: PropertySetDefinition[]
The hierarchy reflects Civil 3D’s layer structure:
  • File - The Civil 3D file
  • Layer - AutoCAD layer (Civil 3D entities are organized by layer)

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Object Types

Civil 3D exports three types of objects:
  1. Civil3dObject - Civil 3D entities (alignments, surfaces, pipes, etc.)
  2. Geometry - Standalone geometry objects
  3. Instance - Block references pointing to Definition proxies

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Civil3dObject Structure

Civil3dObject extends DataObject with these additional fields: 
{
  "id": "string",
  "speckle_type": "Objects.Data.DataObject:Objects.Data.Civil3dObject",
  "applicationId": "string",
  "name": "string",
  "properties": {
    "string": "any value"
  },
  "displayValue": [
    "Base (geometry objects)"
  ],
  "units": "string",
  
  "__comment": "Civil3dObject-specific fields",
  "baseCurves": [
    "ICurve (geometry objects)"
  ]
}

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Connector-Specific Fields

  • baseCurves - An array of curve geometry objects representing the base curves of the Civil 3D entity (e.g., alignment centerline, pipe centerline)

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Properties

Civil3dObject properties contain:
  • Extension Dictionaries - Custom data stored in extension dictionaries
  • XData - Extended entity data
  • Property Sets - Civil 3D property set definitions
  • Part Data - Entity-specific part data
  • Additional class properties - Properties that depend on the entity type (alignment, surface, pipe, etc.)
{
  "properties": {
    "Extension Dictionaries": {
      "CustomApp": {
        "Key": "Value"
      }
    },
    "Property Sets": {
      "Pipe Properties": {
        "Diameter": 0.3,
        "Material": "PVC"
      }
    },
    "Part Data": {
      "Part Family": "Pipe",
      "Part Size": "300mm"
    }
  }
}

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Proxies

Civil 3D models use these proxy types:

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RenderMaterial

Material assignments for visual representation.

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Color

Color assignments for objects.

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Group

Group proxies encode group memberships.

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Definition

Definition proxies store geometry for block definitions.

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PropertySetDefinition

Property set definition proxies encode Civil 3D property set definitions. These define the structure for property sets used by Civil3dObjects.

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Example: Civil3dObject

{
  "id": "civil3d-abc123...",
  "speckle_type": "Objects.Data.DataObject:Objects.Data.Civil3dObject",
  "applicationId": "entity-456",
  "name": "Alignment - Main Road",
  "properties": {
    "Property Sets": {
      "Alignment Properties": {
        "Length": 1250.5,
        "Start Station": 0.0,
        "End Station": 1250.5
      }
    },
    "Part Data": {
      "Entity Type": "Alignment",
      "Style": "Centerline"
    }
  },
  "displayValue": [
    {
      "speckle_type": "Objects.Geometry.Polyline",
      "points": [
        {"x": 0, "y": 0, "z": 0},
        {"x": 100, "y": 50, "z": 0},
        {"x": 200, "y": 100, "z": 0}
      ],
      "units": "meters"
    }
  ],
  "baseCurves": [
    {
      "speckle_type": "Objects.Geometry.Polyline",
      "points": [
        {"x": 0, "y": 0, "z": 0},
        {"x": 100, "y": 50, "z": 0},
        {"x": 200, "y": 100, "z": 0}
      ],
      "units": "meters"
    }
  ],
  "units": "meters"
}

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Invariants and Caveats

  1. baseCurves field - Civil3dObjects have a baseCurves array in addition to displayValue
  2. Property Sets - Civil 3D property sets are stored in properties.Property Sets
  3. Entity-specific properties - Properties vary by entity type (alignment, surface, pipe, etc.)
  4. Layer organization - Objects are organized by AutoCAD layer structure
  5. PropertySetDefinition proxies - Unique to Civil 3D, these define property set structures
  • baseCurves: The fundamental curve geometry of the entity (e.g., alignment centerline, pipe centerline)
  • displayValue: The visual representation (may include additional geometry like labels, annotations, or meshed surfaces)
For some entities, baseCurves and displayValue may contain similar geometry, but displayValue is optimized for visualization.