dwg-tool-parser

name: dwg-tool-parser description: Parse AutoCAD DWG and DXF files into structured JSON summaries with layers, blocks, entity counts, normalized geometry, topology graphs, and civil-survey domain coverage. Use when requests involve boundary/retracement surveys, GPS/GIS surveying, subdivisions/lot line adjustments/easements, site topography/control surveys, construction support surveys (as-built, route, roadway/bridge, hydro), remote/specialized survey tasks, CAD content audits, or DWG-to-DXF analysis pipelines.

DWG Tool Parser

Overview

Use this skill to produce reliable, machine-readable DWG/DXF summaries for land survey and civil engineering workflows first. Prefer the bundled parser script for repeatable output and stable JSON structure across boundary, topo, utility, and roadway drawings.

Workflow

1. Run the parser: python3 scripts/parse_dwg.py <input.dwg|input.dxf> --output <report.json>
2. If input is .dwg, provide a converter command: python3 scripts/parse_dwg.py drawing.dwg --converter-cmd 'odafc "{input}" "{output}"' --output report.json
3. Tune CAD normalization/topology if needed: --precision 6 --tolerance 1e-6 --entity-limit 2000 --topology-entity-limit 5000
4. Add project naming context to tune domain scoring: --project-tag retracement --project-tag roadway --project-tag hydro
5. If you always use the same converter, set DWG_TO_DXF_CMD and omit --converter-cmd.
6. Read the output keys:
   • summary.entity_total
   • summary.geometry_entities_total
   • summary.entity_types
   • summary.layers
   • summary.blocks
   • summary.dxf_version
   • entities
   • topology.nodes
   • topology.edges
   • topology.loops
   • civil_survey.feature_counts
   • civil_survey.terrain
   • civil_survey.parcels
   • civil_survey.centerlines
   • civil_survey.utilities
   • civil_survey.spot_elevations
   • civil_survey.survey_domains
   • civil_survey.project_context
   • civil_survey.qa_flags

Civil/Survey First-Pass Uses

• Parcel and right-of-way extraction from closed boundary polylines.
• Contour/elevation analysis for topo and grading files.
• Centerline and linear-asset length screening.
• Utility/drainage layer signal extraction for network QA.
• Spot elevation and benchmark label harvesting for quick checks.
• Early QA to detect missing units, disconnected topology, or incomplete civil layers.

Domain Coverage Output

The parser maps evidence into these survey domains and reports confidence:

• Boundary and retracement surveys
• GPS and GIS surveying
• Property subdivisions, lot line adjustments, easements
• Site topography and control surveys
• Construction support surveys (as-built, route, roadway/bridge, hydro projects)
• Remote and specialized surveying tasks

Converter Command Rules

• Use a command template that includes both {input} and {output}.
• Quote placeholders in the template so paths with spaces work.
• Optional placeholders are available:
  • {output_dir}
  • {output_stem}
• Example starter template: --converter-cmd 'ODAFileConverter "{input}" "{output_dir}" ACAD2018 DXF 0 1 "{output_stem}.dxf"' Adapt it to your converter's exact CLI syntax.

Output Contract

The parser emits JSON using this schema shape:

{
  "input_file": "...",
  "input_type": "dwg|dxf",
  "parser_backend": "ezdxf|ascii-fallback",
  "conversion": {
    "used": true,
    "command": "...",
    "output_dxf": "..."
  },
  "summary": {
    "dxf_version": "AC1032",
    "insunits": 4,
    "entity_total": 120,
    "geometry_entities_total": 116,
    "entity_types": {
      "LINE": 60
    },
    "layers_total": 8,
    "layers": [
      "0",
      "Walls"
    ],
    "blocks_total": 3,
    "blocks": [
      "DoorTag"
    ]
  },
  "sample_entities": [],
  "entities_total": 120,
  "entities_returned": 120,
  "entities_truncated": false,
  "entities": [
    {
      "id": "10",
      "type": "LINE",
      "layer": "Walls",
      "geometry": {
        "kind": "line",
        "start": [
          0.0,
          0.0,
          0.0
        ],
        "end": [
          10.0,
          0.0,
          0.0
        ]
      }
    }
  ],
  "topology": {
    "tolerance": 1e-06,
    "node_count": 2,
    "edge_count": 1,
    "loop_count": 0,
    "connected_components": 1,
    "nodes": [],
    "edges": [],
    "loops": []
  },
  "civil_survey": {
    "project_context": {
      "project_tags": [
        "retracement",
        "roadway"
      ]
    },
    "survey_domains": {
      "boundary_retracement_surveys": {
        "confidence": "high",
        "score": 5,
        "evidence": [
          "3 closed parcel boundary candidates detected"
        ]
      }
    },
    "feature_counts": {
      "parcel_boundaries": 3,
      "centerlines": 2,
      "contours": 40,
      "spot_elevation_points": 12,
      "spot_elevation_labels": 8,
      "utility_entities": 18,
      "control_points": 4
    },
    "terrain": {
      "contour_count": 40,
      "contour_interval_estimate": 1.0
    },
    "qa_flags": []
  }
}

Troubleshooting

• If .dwg parsing fails, validate your converter command independently.
• If ezdxf is unavailable or cannot parse a DXF, the script falls back to an ASCII parser for core geometry and counts.
• If topology is too large, reduce --topology-entity-limit or increase --tolerance.
• Read references/backends.md for backend selection and template guidance.
• Read references/cad-logic.md for mapping point-based rules into CAD-aware checks.
• Read references/land-survey-civil.md for civil/survey-first output interpretation and rule templates.