sec_interp.gui.adapters.geometry_crs module

CRS, distance-area and sampling-interval helpers for geometry extraction.

sec_interp.gui.adapters.geometry_crs.build_sampling_transform(line_crs: QgsCoordinateReferenceSystem | None, raster_layer: QgsRasterLayer) → QgsCoordinateTransform | None

Build a transform from the line CRS to the raster CRS, or None.

A transform is only needed when both CRSs are known and differ. Across different CRSs, sampling with raw layer coordinates reads the wrong pixels.

Parameters:

  • line_crs – CRS of the section line (None if unknown).

  • raster_layer – The DEM/raster layer being sampled.

Returns:

A QgsCoordinateTransform (line -> raster) or None when the CRSs match, are unknown, or the transform cannot be created.

sec_interp.gui.adapters.geometry_crs.create_distance_area(crs: qgis.core.QgsCoordinateReferenceSystem) → qgis.core.QgsDistanceArea

Create and configure a QgsDistanceArea object.

sec_interp.gui.adapters.geometry_crs.raster_resolution_in_crs(raster_layer: QgsRasterLayer, target_crs: QgsCoordinateReferenceSystem | None) → float | None

Return the raster pixel size expressed in target_crs units.

rasterUnitsPerPixelX() is expressed in the raster’s own CRS. When the section line lives in a different CRS (on-the-fly reprojection), using that value directly as a sampling interval is meaningless and can densify the line into millions of vertices. This transforms a one-pixel-long segment from the raster CRS into target_crs to recover a usable interval.

Parameters:

  • raster_layer – The DEM/raster layer.

  • target_crs – CRS in which to express the resolution (None to return the raw value).

Returns:

Pixel size in target_crs units, or None if it cannot be determined.

sec_interp.gui.adapters.geometry_crs.resolve_sampling_interval(geometry: QgsGeometry, raster_layer: QgsRasterLayer, line_crs: QgsCoordinateReferenceSystem | None) → float

Resolve a safe sampling interval for a raster profile.

Prefers the DEM pixel size expressed in the line’s CRS. Falls back to a length-derived interval when the resolution cannot be resolved, and always returns a strictly positive value.

Parameters:

  • geometry – The section line geometry (in line_crs units).

  • raster_layer – The DEM/raster layer.

  • line_crs – CRS of the section line (None if unknown).

Returns:

A positive sampling interval in line_crs units.