3.11 Convert points to polygon - LUPMISManual

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3. GIS operations

3.11 Convert Points to Polygon

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

If you do a ground survey collecting points (‘waypoints’), which define a parcel or a plot of land, you will have to change these points to a polygon.

Edit > Show Selection Manager > With the Select-tool (at toolbar left) you select the points > Selection Manager window: Selection > Check that you have only these points, no areas

If there is an area selected (or a wrong point):
Pick it (1, see below) > Remove from selection (2) >

2. Convert points to line:
Actions (3) > Basic operations > Points to line > A line in red (i.e. selected) should be drawn, which is not closed yet

3. Draw a 'closing' line:  
Line-tool (at toolbar left) > Draw a line between the two end points of the previous line > Right-click > Line window: Actions > Snap to live layer > OK > Snap to live layer window: Snap to a maximum distance on screen of 10 pixels > OK

, you can use the Edit-tool with ‘Snap vertex to nearest vertex’ option.

4. Convert line to polygon:
Select-tool (at toolbar left) > Select the 2 (or more) lines, which will form the polygon > Selection Manager window: Actions > Polygon manipulation > Convert lines to polygons > Convert lines to polygons window: Snap: 0 (all others in default) > OK

If there is a polygon next to the new polygon, you better adjust the boundary:  
Snap-tool (at toolbar left) > Click on the new polygon very close to the boundary > Click again on the other side, read the maximum distance, it will move the boundary

5. Don’t forget to save.

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Similar to the task of converting lines to polygons, you can also convert lines of a layer to a polygon (see  Chapter 3.4).

See also  Annex 16.3, if you have the coordinates of a parcel from field survey in a digital format, which you like to import and form a polygon.


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