preview_stream_corridor.RdBoundary-aware processing uses sf/GEOS in a local WGS84 azimuthal equidistant CRS in metres. Geographic edges are densified to at most 100 m before projection, using sf/lwgeom. A 1 mm overlay grid and 2 mm line-clipping/containment precision margin handle shared edges; the final area clips to the unexpanded parent. Line remnants of at most 4 mm are discarded. These numerical settings are not source-accuracy claims. Supports regional parents at most 6 degrees wide/high between 80 S and 80 N; not dateline-crossing areas. Without a boundary, uses an sf/S2 spherical outer buffer (10,000 cells). Neither method delineates a floodplain, repairs a network, or chooses the terrain analysis CRS.
preview_stream_corridor(lines, distance, unit = "m", boundary = NULL)sf with 1 to 500 valid nonempty finite XY line features and a CRS.
Positive buffer distance on EACH side of the lines, at most 10,000 m.
"m" or international "ft" (exactly 0.3048 m).
Optional regional Study Area polygon. Clip selected lines first, buffer their retained portions, then clip the area. NULL returns an unrestricted buffer.
List with area (one CRS-defined MULTIPOLYGON), distance_m, selected_features, polygon_parts, method, unclipped_area, clipped and removed_area_m2. Boundary previews also return clipped_lines (source attributes and projected retained geometry), source_rows (indices into the input), line_lengths (source_row, original_m, retained_m, including zero-length discarded rows), retained_features, line_clipped and processing_crs (WKT). Boundary output retains its metric CRS; unrestricted output is WGS84. No files are written.