Level of expertise required for this Chapter: Expert; general Map Maker training
If you perform operations, which result in loss of styles, labels or attribute data, you have to extract this information prior to a seed layer. A seed layer consists of points, one for each polygon, containing the information of the polygon behind it. This is normally required for intersect / unite operations (Chapter 3.3) but not for the cutter-tool (Chapter 2.8) (if the cutter options are set correctly, see Annex 1.1.6) and also not for clipping units according to other unit (Chapter 3.6).
1. Create a seed layer: Right-mouse > Live layer actions > Live layer actions window: Basic operations > Create seed points from polygons > OK and save this new point (seed) layer under a temporary file name.
2. You can now perform all 'sensitive' operations. Don’t worry about styles, labels, attributes.
3. To regain your styles, labels, attributes, you have to reload this information from the seed layer:
Right-mouse > Live layer actions > Live layer actions window: Spatial queries > Polygons inherit attributes from seed points > OK
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Note 1: Be aware, that ‘unseeded’ polygons will disappear.
Note 2: If a polygon has been cut, the newly ‘cut’ part might not have a seed point and therefore be deleted. If you want to avoid this, you have to add a seed point to this area.
Note 3: If two seed points occur above one polygon (either by joining two units, or by moving a seed point), the result will be unpredictable.