4 - Preprocess Categrozie Wooded Area#

Algorithm ID: hedgetools:preprocesscwa

This tool prepares a tree cover vector layer obtained from Generate Tree Cover for the Categorize Wooded Area algorithm.

Since vector layers created from rasters can be very large, This tool will:

Simplify geometries.
Remove holes inside polygons and eliminate small geometries.
Repair invalid geometries.

Parameters#

Label	Name	Type	Description
Input tree cover layer	`INPUT`	[vector: polygon]	Polygon vector layer.
Area threshold for geometry deletion (square meters)	`MIN_AREA`	[numeric: double] Default: 20.0	Geometries smaller than this value will be deleted.
Shift tolerance for simplification (meters)	`TOLERANCE`	[numeric: double] Default: 0.25	Vertices that do not move the polygon boundary beyond this threshold will be removed during simplification.
Area threshold for filling polygon holes (square meters)	`HOLE_SIZE`	[numeric: double] Default: 50.0	Holes smaller than this value will be filled.
Output preprocessed tree cover layer	`OUTPUT`	[vector: polygon] Default: `[Create temporary layer]`	Output polygon vector layer.

Warning

Polygons with many holes can cause issues when splitting them in either Topological Polygons or in the Data - Transformation module. This may result in incorrect solutions or failures during the splitting process.

Outputs#

Label	Name	Type	Description
Output preprocessed tree cover layer	`OUTPUT`	[vector: polygon]	Preprocessed tree cover vector layer.