4.9 Transfer attribute data from points to polygons - LUPMISManual

4.9 Transfer Attribute Data from Points to Polygons

Level of expertise required for this Chapter: Advanced; general Map Maker training

This process of transferring attribute data from one layer to another, also called ‘inheriting’, is important to assign data to polygons. At TCPD, there are two versions frequently required.

4.9.1 Transfer from Point (per polygon) to Polygon

You have points, and you want to transfer their attribute data to the polygon, from one point per polygon. For example, administrative units have been mapped (digitized), but the characteristics (attribute data) are in the GIS with point data.

The illustration at the right shows the regions of Ghana, to where you want to transfer (‘inherit’) population data from the database attached to the capitals.

1. Load two layers: Polygons (regions) without any database, and copy it to the live layer, and points (regional capitals) with the attached database in the passive layer. It is recommended, that you have only these two layers in Map Maker.

2. Main menu > Edit > Live layer data > Live layer inherit data from layers… (See above, if this is grayed out, you don’t have a layer in your live layer)

3. Inherit data window: Select all, and style numbers and display labels, if required. The polygon inheritance rule applies only, if you transfer from polygons to polygons, i.e. not in this example.

4. OK

5. Don’t forget to save.

4.9.2 Transfer from Major Polygon to Minor Polygon

You have a large area with given characteristics, and you want to transfer these attributes to all small polygons, which lie completely or dominantly within the large polygon. For example, a sector has been digitized and labelled, also many parcels, which lie within the sector.

1. Load two layers: The small polygons (parcels), and copy it to the live layer, and the major polygon (sector) with the style and / or display labels in the passive layer. It is recommended, that you have only these two layers in Map Maker.

2. Main menu > Edit > Live layer data > Live layer inherit data from layers… (See above, if this is greyed out, you don’t have a layer in your live layer)

3. Inherit data window: Tick style numbers and display labels. The polygon inheritance rule should be on: live layer label points in passive layer polygons.

4. OK

5. Don’t forget to save.