SecInterp - Technical Compendium

This document consolidates technical research, geophysical algorithms, and API references for the SecInterp plugin.

---

🔬 Scientific & Geophysical Research

1. Integration of Geophysics

The plugin is prepared for future integration of deep geophysical data:

• Potential (SP): Projections use normalized dot product for section alignment and absolute elevation calculation ($Z_{collar} - Depth$).

• VES (SEV): Resistivity models are visualized as blocks on a logarithmic scale ($\log_{10}(Rho)$) using thickness-to-elevation conversion.

2. Drillhole Modeling

• Desurveying: Trayectories are calculated using the Average Angle Method (Tangential tracking).

• Projection: 3D trajectories are mapped to the 2D plane by calculating distance along the section line while preserving absolute Z.

3. Core Algorithms

• Distance & Sampling: We use QgsDistanceArea.measureLine() and direct dataProvider() access for DEM sampling, yielding a ~30% performance boost over high-level processing algorithms.

• Adaptive LOD: Uses the Douglas-Peucker (RDP) algorithm for line simplification and a curvature-based hysteresis logic to adjust sampling density dynamically during zoom.

---

🔧 API Reference

Core Services (core/services/)

GeologyService

• build_segments(context, feedback=None): Intersects section lines with geological geometry.

• Returns: List[GeologySegment].

StructureService

• project_structures(context, feedback=None): Projects 3D structural data and calculates apparent dip.

• Formula: tan(beta) = tan(alpha) * |cos(strike - azimuth)|.

DrillholeService

• process_context(context, feedback=None): Full drillhole pipeline.

• Architecture: Decomposed into CollarProcessor, SurveyProcessor, IntervalProcessor, TrajectoryEngine, ProjectionEngine.

PreviewService

• generate_all(params, transform_context): Orchestrates topography + structures for the preview.

• calculate_max_points(canvas_width, manual_max, auto_lod): Adaptive LOD.

AccessControlService

• can_export_3d(): Gates 3D export via QgsSettings (SecInterp/enable_3d).

Export package (core/services/export/)

• ExportService.export_data(output_folder, params, ...): facade over handlers/ (one per data type).

• Note: topography extraction lives in the GUI adapter gui/adapters/profile_extractor.py (ProfileExtractor.extract_profile), not in core/services/.

---

🛡️ Validation Framework

Modularized in core/validation/:

• FieldValidator: Numeric and existence checks.

• LayerValidator: CRS, geometry, and feature count validation.

• PathValidator: Security and permission handling.

• ProjectValidator: High-level orchestration.

---

🧬 Key Data Structures

GeologySegment

Used to represent both surface outcrops and drillhole intervals (QGIS-agnostic: WKT, not QgsGeometry).

@dataclass
class GeologySegment:
    unit_name: str
    geometry_wkt: DomainGeometry | None
    attributes: dict[str, Any]
    points: list[tuple[float, float]]

StructureMeasurement

@dataclass
class StructureMeasurement:
    distance: float
    elevation: float
    apparent_dip: float
    original_dip: float
    original_strike: float
    attributes: dict[str, Any]