Outlines the line with 1 (white) on a 0 (black) map.
Typical use case is painting the roads with textures on terrain.
When Hardness is set to 0 Stroke node could be used to determine the distance to line. Returned map value 1 will mean that map pixel is nearly the line, value 0 means that it is on a Width distance or further.
Width: the size of the outlined line, in world units. If the width value is lower than one map pixel size, makes the spline transparent (i.e. setting this pixel "partly filled").
Hardness: the percentage of fully filled width compared to the total width. Varies from 0 (only the center pixel has the value of one) to 1 (all pixels within width have the value 1).