bufferqgisvector
I'm working with buildings in QGIS (vector polygons) and have two layers – call them a "source" building and multiple "sink" buildings (in second layer). How would I go about finding the minimum and maximum buffer from the "source" building required to "cover" the sink "buildings"?
Put in another way if I keep extending the buffer outwards of the "source" building, how can I get the difference between where this buffer first intersects a "sink" building and last intersects it?
Yes, you need a layer that covers the same area to calculate the difference. The easiest way is to create a buffer around the centerpoint.
If you already have a layer that includes a point feature at the centerpoint, you can select that and then use the Vector/Geprocessing/Buffer tool with the "Use only selected features" check box activated.
If you don't have a point feature at the centerpoint, you can create a new point shapefile and adding a point, probably using the Numerical Digitize plugin to get an accurate position of the point. Then you can run the Buffer tool on that layer.
I think you are currently using QGIS 3.0.0 or 3.0.1.
Latest QGIS 3.0.2 does not have Variable distance buffer anymore.
What you can find in the Vector | Geoprocessing Tools menu would simply be a Buffer.
It is the same in the Processing Toolbox... First. Fixed distance buffer disappeared, and now Variable distance buffer. There is only Buffer tool left.
Now with this Buffer tool, you will easily find Distance option. In case you need to apply a variable distance, click on the Data defined override icon and select the field you want to assign to.
Best Answer
Step 1: Make sure your sinks have a unique ID.
Step 2: Use
extract verticeson your "sink" features.Step 3: Run
join attributes by nearestwith your source features as first input and the extracted vertices as second input. Be sure to change the number of nearest neighbours so it meets or exceeds you maximum number of vertices on your "sink" features. The tool adds the direction and distance to the vertices to the attribute table of the source features.Step 4: In order to get the minimum distance to the next sink for each source, run
minimum("distance",group_by:="Unique ID of the sinks")- insert the unique ID attribute name accordingly.Step 5: In order to get the maximum distance, run
maximum("distance",group_by:="Unique ID of the sink").