2.16 Create ‘Doughnut’
Level of expertise required for this Chapter: Intermediate; general Map Maker training
A ‘doughnut’ - in GIS terms - is a ring-shaped polygon with an empty area inside.
1. Create the whole shape by digitizing the outer boundary of the polygon with the Polygon-tool from the toolbar left.
2.Create the ‘hole’ (island) by digitizing the inner line with the Polygon-tool.
You now have two polygons overlapping each other.
3. You extract the inner area from the larger polygon area with the Join-tool from the toolbar left. Start in the outer polygon (ring) and drag to the inner area.
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You apply the same process to any area, which is to be cut from a polygon: Join-tool, dragging from the remaining polygon to the extracted area.