Advance Guide
Spatial Layout Reconstruction
How RustO! reconstructs human-readable 2D spatial layouts for multi-column tables, invoices, receipts, and forms.
Standard OCR engines return a flat list of disconnected bounding boxes, losing table structures, column gaps, and line indentations.
RustO! includes a built-in Spatial Layout Reconstruction Engine that analyzes 2D geometric relationships to produce formatted, visually aligned text.
🎯 How the Algorithm Works
Rendering diagram...
Visual Comparison: Output Modes
Consider a standard retail invoice with two item rows and two columns:
1. Flat Line List (output: "lines")
Item Description
Amount
Coffee Latte
$4.50
Croissant
$3.50
Total
$8.00
(Notice how column relationships are flattened into a single vertical sequence).
2. Reconstructed Spatial Text (output: "spatial")
Item Description Amount
Coffee Latte $4.50
Croissant $3.50
─────────────────────────────────────────────
Total $8.00
(Column headers, tabular items, and total rows remain aligned in their original 2D positions).
⚙️ Tuning Spatial Parameters
Spatial reconstruction is controlled at runtime via OcrRunOptions:
let options = OcrRunOptions {
output: OutputGranularity::Spatial,
line_y_threshold: Some(0.5), // Vertical row clustering tolerance
word_x_threshold: Some(0.4), // Horizontal word & column spacing tolerance
..Default::default()
};
Parameter Guidelines
| Parameter | Default | When to Increase | When to Decrease |
|---|---|---|---|
lineYThreshold | 0.5 | Increase (0.7 - 0.9) if slightly wavy, handheld, or skewed receipt lines get fragmented into multiple lines. | Decrease (0.2 - 0.35) for dense spreadsheets or multi-line tables where rows are packed tightly together. |
wordXThreshold | 0.4 | Increase (0.6 - 0.8) to merge spaced words across wider gaps into single phrases. | Decrease (0.2 - 0.3) to preserve distinct column boundaries in tightly aligned data tables. |
💡 Practical Examples by Platform
Rust
let spatial_text = match ocr.detect_text(&image_source, &OcrRunOptions {
output: OutputGranularity::Spatial,
line_y_threshold: Some(0.5),
word_x_threshold: Some(0.4),
..Default::default()
})? {
DetectTextResult::Spatial(text) => text,
_ => unreachable!(),
};
println!("{spatial_text}");
React Native
const formattedLayout = await detectText(
{ uri: 'file:///path/to/invoice.jpg' },
{
output: 'spatial',
lineYThreshold: 0.5,
wordXThreshold: 0.4,
}
);
console.log(formattedLayout);