sec_interp.core.utils.sampling module

Sampling Utilities Module.

This module provides elevation sampling and profile context preparation tools.

sec_interp.core.utils.sampling.interpolate_elevation(topo_data: list, distance: float) → float

Interpolate elevation at a given distance along the topography profile.

Uses linear interpolation between the two nearest sampled points.

Parameters:

  • topo_data – List of (distance, elevation) tuples.

  • distance – Horizontal distance along the section.

Returns:

The interpolated elevation value (Z) at that distance.

sec_interp.core.utils.sampling.prepare_profile_context(line_lyr: qgis.core.QgsVectorLayer) → tuple[qgis.core.QgsGeometry, qgis.core.QgsPointXY, qgis.core.QgsDistanceArea]

Prepare a common context for profile calculation operations.

Parameters:

line_lyr – The cross-section line vector layer.

Returns:

  • line_geom: The geometry of the section line.

  • line_start: The starting point of the line.

  • distance_area: Fully configured geodesic distance object.

Return type:

A tuple containing

Raises:

ValueError – If the input layer is empty or has invalid geometry.

sec_interp.core.utils.sampling.sample_elevation_along_line(geometry: QgsGeometry, raster_layer: QgsRasterLayer, band_number: int, distance_area: QgsDistanceArea, reference_point: QgsPointXY | None = None, interval: float | None = None) → list[QgsPointXY]

Sample elevation values along a line geometry from a raster layer.

Densifies the line at raster resolution and samples the elevation at each vertex.

Parameters:

  • geometry – The line geometry to sample along.

  • raster_layer – The source DEM raster layer.

  • band_number – The raster band index to sample.

  • distance_area – Object for geodesic distance calculations.

  • reference_point – Optional start point for distance measurements.

  • interval – Optional sampling interval. If None, uses raster resolution.

Returns:

A list of QgsPointXY objects where x is horizontal distance and y is elevation.

sec_interp.core.utils.sampling.sample_point_elevation(raster_layer: qgis.core.QgsRasterLayer, point: qgis.core.QgsPointXY, band_number: int = 1) → float

Sample elevation from a raster layer at a specific 2D coordinate.

Parameters:

  • raster_layer – The DEM raster layer.

  • point – The coordinate point (X, Y) to sample.

  • band_number – The raster band index (default 1).

Returns:

The sampled elevation value (Z) or 0.0 if the point is out of bounds.