dgn-to-excel

# DGN to Excel Conversion

## Business Case

### Problem Statement
DGN files are common in infrastructure and civil engineering:
- Transportation and highway design
- Bridge and tunnel projects
- Utility networks
- Rail infrastructure

Extracting structured data from DGN files for analysis and reporting can be challenging.

### Solution
Convert DGN files to structured Excel databases, supporting both v7 and v8 formats.

### Business Value
- **Infrastructure support** - Civil engineering focused
- **Legacy format support** - V7 and V8 DGN files
- **Data extraction** - Levels, cells, text, geometry
- **Batch processing** - Process multiple files
- **Structured output** - Excel format for analysis

## Technical Implementation

### CLI Syntax
```bash
DgnExporter.exe <input_dgn>
```

### Supported Versions
| Version | Description |
|---------|-------------|
| V7 DGN | Legacy MicroStation format (pre-V8) |
| V8 DGN | Modern MicroStation format |
| V8i DGN | MicroStation V8i format |

### Output Format
| Output | Description |
|--------|-------------|
| `.xlsx` | Excel database with all elements |

### Examples

```bash
# Basic conversion
DgnExporter.exe "C:\Projects\Bridge.dgn"

# Batch processing
for /R "C:\Infrastructure" %f in (*.dgn) do DgnExporter.exe "%f"

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

### Python Integration

```python
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 DGNElementType(Enum):
    """DGN element types."""
    CELL_HEADER = 2
    LINE = 3
    LINE_STRING = 4
    SHAPE = 6
    TEXT_NODE = 7
    CURVE = 11
    COMPLEX_CHAIN = 12
    COMPLEX_SHAPE = 14
    ELLIPSE = 15
    ARC = 16
    TEXT = 17
    SURFACE = 18
    SOLID = 19
    BSPLINE_CURVE = 21
    PO...