Dwg To Excel

DWG to Excel Conversion

Business Case

Problem Statement

AutoCAD DWG files contain valuable project data locked in proprietary format:

• Layer structures with drawing organization
• Block references with attribute data
• Text annotations and dimensions
• Geometric entities (lines, polylines, arcs)
• External references (xrefs)

Extracting this data typically requires AutoCAD licenses or complex programming.

Solution

DwgExporter.exe converts DWG files to structured Excel databases offline, without Autodesk licenses.

Business Value

• Zero license cost - No AutoCAD license required
• Legacy support - Reads DWG files from 1983 to 2026
• Data extraction - Layers, blocks, attributes, text, geometry
• PDF export - Generate drawings from DWG layouts
• Batch processing - Convert thousands of DWG files

Technical Implementation

CLI Syntax

bashCopy code
DwgExporter.exe <input_dwg> [options]

Output Formats

Supported Versions

Examples

bashCopy code
# Basic conversion
DwgExporter.exe "C:\Projects\FloorPlan.dwg"

# Export with PDF drawings
DwgExporter.exe "C:\Projects\FloorPlan.dwg" sheets2pdf

# Batch processing all DWG in folder
for /R "C:\Projects" %f in (*.dwg) do DwgExporter.exe "%f"

# PowerShell batch conversion
Get-ChildItem "C:\Projects\*.dwg" -Recurse | ForEach-Object {
    & "C:\DDC\DwgExporter.exe" $_.FullName
}

Python Integration

pythonCopy code
import subprocess
import pandas as pd
from pathlib import Path
from typing import List, Optional, Dict, Any
from dataclasses import dataclass
from enum import Enum


class DWGEntityType(Enum):
    """DWG entity types."""
    LINE = "LINE"
    POLYLINE = "POLYLINE"
    LWPOLYLINE = "LWPOLYLINE"
    CIRCLE = "CIRCLE"
    ARC = "ARC"
    ELLIPSE = "ELLIPSE"
    SPLINE = "SPLINE"
    TEXT = "TEXT"
    MTEXT = "MTEXT"
    DIMENSION = "DIMENSION"
    INSERT = "INSERT"  # Block reference
    HATCH = "HATCH"
    SOLID = "SOLID"
    POINT = "POINT"
    ATTRIB = "ATTRIB"
    ATTDEF = "ATTDEF"


@dataclass
class DWGEntity:
    """Represents a DWG entity."""
    handle: str
    entity_type: str
    layer: str
    color: int
    linetype: str
    lineweight: float

    # Geometry (depends on entity type)
    start_x: Optional[float] = None
    start_y: Optional[float] = None
    end_x: Optional[float] = None
    end_y: Optional[float] = None

    # Block reference data
    block_name: Optional[str] = None
    rotation: Optional[float] = None
    scale_x: Optional[float] = None
    scale_y: Optional[float] = None

    # Text data
    text_content: Optional[str] = None
    text_height: Optional[float] = None


@dataclass
class DWGBlock:
    """Represents a DWG block definition."""
    name: str
    base_point_x: float
    base_point_y: float
    entity_count: int
    is_dynamic: bool
    attributes: List[str]


@dataclass
class DWGLayer:
    """Represents a DWG layer."""
    name: str
    color: int
    linetype: str
    is_on: bool
    is_frozen: bool
    is_locked: bool
    lineweight: float
    entity_count: int


class DWGExporter:
    """DWG to Excel converter using DDC DwgExporter CLI."""

    def __init__(self, exporter_path: str = "DwgExporter.exe"):
        self.exporter = Path(exporter_path)
        if not self.exporter.exists():
            raise FileNotFoundError(f"DwgExporter not found: {exporter_path}")

    def convert(self, dwg_file: str,
                export_pdf: bool = False) -> Path:
        """Convert DWG file to Excel."""
        dwg_path = Path(dwg_file)
        if not dwg_path.exists():
            raise FileNotFoundError(f"DWG file not found: {dwg_file}")

        cmd = [str(self.exporter), str(dwg_path)]
        if export_pdf:
            cmd.append("sheets2pdf")

        result = subprocess.run(cmd, capture_output=True, text=True)

        if result.returncode != 0:
            raise RuntimeError(f"Export failed: {result.stderr}")

        # Output file is same name with .xlsx extension
        return dwg_path.with_suffix('.xlsx')

    def batch_convert(self, folder: str,
                      include_subfolders: bool = True,
                      export_pdf: bool = False) -> List[Dict[str, Any]]:
        """Convert all DWG files in folder."""
        folder_path = Path(folder)
        pattern = "**/*.dwg" if include_subfolders else "*.dwg"

        results = []
        for dwg_file in folder_path.glob(pattern):
            try:
                output = self.convert(str(dwg_file), export_pdf)
                results.append({
                    'input': str(dwg_file),
                    'output': str(output),
                    'status': 'success'
                })
                print(f"✓ Converted: {dwg_file.name}")
            except Exception as e:
                results.append({
                    'input': str(dwg_file),
                    'output': None,
                    'status': 'failed',
                    'error': str(e)
                })
                print(f"✗ Failed: {dwg_file.name} - {e}")

        return results

    def read_entities(self, xlsx_file: str) -> pd.DataFrame:
        """Read converted Excel as DataFrame."""
        xlsx_path = Path(xlsx_file)
        if not xlsx_path.exists():
            raise FileNotFoundError(f"Excel file not found: {xlsx_file}")

        return pd.read_excel(xlsx_file, sheet_name="Elements")

    def get_layers(self, xlsx_file: str) -> pd.DataFrame:
        """Get layer summary from converted file."""
        df = self.read_entities(xlsx_file)

        if 'Layer' not in df.columns:
            raise ValueError("Layer column not found in data")

        summary = df.groupby('Layer').agg({
            'Handle': 'count'
        }).reset_index()
        summary.columns = ['Layer', 'Entity_Count']
        return summary.sort_values('Entity_Count', ascending=False)

    def get_blocks(self, xlsx_file: str) -> pd.DataFrame:
        """Get block reference summary."""
        df = self.read_entities(xlsx_file)

        # Filter to INSERT entities (block references)
        blocks = df[df['EntityType'] == 'INSERT']

        if blocks.empty:
            return pd.DataFrame(columns=['Block_Name', 'Count'])

        summary = blocks.groupby('BlockName').agg({
            'Handle': 'count'
        }).reset_index()
        summary.columns = ['Block_Name', 'Count']
        return summary.sort_values('Count', ascending=False)

    def get_text_content(self, xlsx_file: str) -> pd.DataFrame:
        """Extract all text content from DWG."""
        df = self.read_entities(xlsx_file)

        # Filter to text entities
        text_types = ['TEXT', 'MTEXT', 'ATTRIB']
        texts = df[df['EntityType'].isin(text_types)]

        if 'TextContent' in texts.columns:
            return texts[['Handle', 'EntityType', 'Layer', 'TextContent']].copy()
        return texts[['Handle', 'EntityType', 'Layer']].copy()

    def get_entity_statistics(self, xlsx_file: str) -> Dict[str, int]:
        """Get entity type statistics."""
        df = self.read_entities(xlsx_file)

        if 'EntityType' not in df.columns:
            return {}

        return df['EntityType'].value_counts().to_dict()

    def extract_block_attributes(self, xlsx_file: str,
                                  block_name: str) -> pd.DataFrame:
        """Extract attributes from specific block type."""
        df = self.read_entities(xlsx_file)

        # Find block references
        blocks = df[(df['EntityType'] == 'INSERT') &
                    (df['BlockName'] == block_name)]

        # Find associated attributes
        # Attributes typically follow their parent INSERT in handle order
        result_data = []

        for _, block in blocks.iterrows():
            block_handle = block['Handle']
            block_data = {
                'Block_Handle': block_handle,
                'X': block.get('InsertX', 0),
                'Y': block.get('InsertY', 0),
                'Rotation': block.get('Rotation', 0)
            }

            # Add any attribute columns
            for col in df.columns:
                if col.startswith('Attr_'):
                    block_data[col] = block.get(col)

            result_data.append(block_data)

        return pd.DataFrame(result_data)


class DWGAnalyzer:
    """Advanced DWG analysis tools."""

    def __init__(self, exporter: DWGExporter):
        self.exporter = exporter

    def analyze_drawing_structure(self, dwg_file: str) -> Dict[str, Any]:
        """Analyze complete drawing structure."""
        xlsx = self.exporter.convert(dwg_file)
        df = self.exporter.read_entities(str(xlsx))

        analysis = {
            'file': dwg_file,
            'total_entities': len(df),
            'layers': self.exporter.get_layers(str(xlsx)).to_dict('records'),
            'entity_types': self.exporter.get_entity_statistics(str(xlsx)),
            'blocks': self.exporter.get_blocks(str(xlsx)).to_dict('records')
        }

        # Calculate extents if coordinates available
        if 'X' in df.columns and 'Y' in df.columns:
            analysis['extents'] = {
                'min_x': df['X'].min(),
                'max_x': df['X'].max(),
                'min_y': df['Y'].min(),
                'max_y': df['Y'].max()
            }

        return analysis

    def compare_drawings(self, dwg1: str, dwg2: str) -> Dict[str, Any]:
        """Compare two DWG files."""
        xlsx1 = self.exporter.convert(dwg1)
        xlsx2 = self.exporter.convert(dwg2)

        df1 = self.exporter.read_entities(str(xlsx1))
        df2 = self.exporter.read_entities(str(xlsx2))

        layers1 = set(df1['Layer'].unique()) if 'Layer' in df1.columns else set()
        layers2 = set(df2['Layer'].unique()) if 'Layer' in df2.columns else set()

        return {
            'file1': dwg1,
            'file2': dwg2,
            'entity_count_diff': len(df2) - len(df1),
            'layers_added': list(layers2 - layers1),
            'layers_removed': list(layers1 - layers2),
            'common_layers': list(layers1 & layers2)
        }

    def find_duplicates(self, xlsx_file: str,
                        tolerance: float = 0.001) -> pd.DataFrame:
        """Find duplicate entities at same location."""
        df = self.exporter.read_entities(xlsx_file)

        if 'X' not in df.columns or 'Y' not in df.columns:
            return pd.DataFrame()

        # Round coordinates for grouping
        df['X_rounded'] = (df['X'] / tolerance).round() * tolerance
        df['Y_rounded'] = (df['Y'] / tolerance).round() * tolerance

        # Find duplicates
        duplicates = df[df.duplicated(
            subset=['EntityType', 'Layer', 'X_rounded', 'Y_rounded'],
            keep=False
        )]

        return duplicates.sort_values(['X_rounded', 'Y_rounded'])


# Convenience functions
def convert_dwg_to_excel(dwg_file: str,
                         exporter_path: str = "DwgExporter.exe") -> str:
    """Quick conversion of DWG to Excel."""
    exporter = DWGExporter(exporter_path)
    output = exporter.convert(dwg_file)
    return str(output)


def batch_convert_dwg(folder: str,
                      exporter_path: str = "DwgExporter.exe",
                      include_subfolders: bool = True) -> List[str]:
    """Batch convert all DWG files in folder."""
    exporter = DWGExporter(exporter_path)
    results = exporter.batch_convert(folder, include_subfolders)
    return [r['output'] for r in results if r['status'] == 'success']

Output Structure

Excel Sheets

Entity Columns

Quick Start

pythonCopy code
# Initialize exporter
exporter = DWGExporter("C:/DDC/DwgExporter.exe")

# Convert single file
xlsx = exporter.convert("C:/Projects/Plan.dwg")
print(f"Output: {xlsx}")

# Read and analyze
df = exporter.read_entities(str(xlsx))
print(f"Total entities: {len(df)}")

# Get layer statistics
layers = exporter.get_layers(str(xlsx))
print(layers)

# Get block usage
blocks = exporter.get_blocks(str(xlsx))
print(blocks)

# Extract text annotations
texts = exporter.get_text_content(str(xlsx))
for _, row in texts.iterrows():
    print(f"{row['Layer']}: {row.get('TextContent', 'N/A')}")

Common Use Cases

1. Layer Audit

pythonCopy code
exporter = DWGExporter()
xlsx = exporter.convert("drawing.dwg")
layers = exporter.get_layers(str(xlsx))

# Check for non-standard layers
standard_layers = ['0', 'WALLS', 'DOORS', 'WINDOWS', 'DIMENSIONS']
non_standard = layers[~layers['Layer'].isin(standard_layers)]
print("Non-standard layers:", non_standard['Layer'].tolist())

2. Block Schedule

pythonCopy code
# Extract all door blocks with attributes
doors = exporter.extract_block_attributes(str(xlsx), "DOOR")
print(doors[['Block_Handle', 'Attr_DOOR_TYPE', 'Attr_DOOR_SIZE']])

3. Drawing Comparison

pythonCopy code
analyzer = DWGAnalyzer(exporter)
diff = analyzer.compare_drawings("rev1.dwg", "rev2.dwg")
print(f"Entities added: {diff['entity_count_diff']}")
print(f"New layers: {diff['layers_added']}")

Integration with DDC Pipeline

pythonCopy code
# Full pipeline: DWG → Excel → Analysis → Report
from dwg_exporter import DWGExporter, DWGAnalyzer

# 1. Convert DWG
exporter = DWGExporter("C:/DDC/DwgExporter.exe")
xlsx = exporter.convert("project.dwg")

# 2. Analyze structure
analyzer = DWGAnalyzer(exporter)
analysis = analyzer.analyze_drawing_structure("project.dwg")

# 3. Generate report
print(f"Drawing: {analysis['file']}")
print(f"Entities: {analysis['total_entities']}")
print(f"Layers: {len(analysis['layers'])}")
print(f"Blocks: {len(analysis['blocks'])}")

Best Practices

1. Check DWG version - Older files may have limited data
2. Validate layer structure - Clean up before processing
3. Handle external references - Bind xrefs if needed
4. Batch overnight - Large files take time
5. Verify entity counts - Compare with AutoCAD if possible

Resources

• GitHub: cad2data Pipeline
• Video Tutorial: DWG to Excel Pipeline
• DDC Book: Chapter 2.4 - CAD Data Extraction