With Intersection, you place two layers on top of each other and create a new layer of the area that occurs in both layers.
In the Toolbar menu, click on Vector
In the drop-down options menu, choose Geoprocessing Tools
Click on Intersection to open the intersection window
At Input, fill in the layer whose objects you wish to maintain in the map image
Below that, fill in the layer which you want to make an overlap with
Give the new layer a name or opt for a temporary layer
Click on OK
When you open the Attribute Table of the new layer, you will see that Qgis has made new objects (areas or lines) due to the overlap. A feature from the input layer that intersects with five objects from the intersect layer, will be turned by Qgis into five objects in the new table.
With Symmetrical Difference, you place two layers on top of each other. You will create a new layer consisting of all the objects that are only in one of either layers. The overlapping objects are not included. When an object partially intersects, only the non-intersecting part will be included in the new layer. In the Attribute Table, the objects from both layers are included, but not changed.
Choose Geoprocessing Tools in the drop-down options menu
Click on Symmetrical Difference to open the window
At Input Layer, fill in the layer whose objects you wish to maintain in the map image
At Difference Layer, fill in the layer which you want to make an overlap with
Give the new layer a name or opt for a temporary layer
Click on OK
A buffer is an area around an object. This may be a point, line or polygon. You can choose the buffer’s distance yourself. Qgis will then calculate a number of points at a distance from the object and connect these points by means of a line. How many points Qgis will calculate; so how accurate the buffer is, is something that you can determine yourself by choosing the number of segments. In the case of a buffer around a certain point, Qgis will create a circle-shaped area. The number of segments determines the extent to which the circle shape is approximated and you will fill this in for a quarter of the shape. If the number is 2, the buffer in Qgis will create an octagon.
Click on Vector in the Toolbar menu
In the drop-down menu, choose Geoprocessing Tools
Click on Fixed Distance Buffer
At Input Layer, choose the layer with objects around which you wish to create a buffer (goat farms)
At Distance, choose the desired distance between the buffer boundary and the object – please note that the distance is noted in map units here. The map unit is fixed per CRS. For Amersfoort RD New, the distance notation is metres.
Choose the number of Segments
Select a temporary layer or save it under a new name
Click on Run
A buffer is an area around an object. With Variable Distance Buffer you can create differently sized buffers for different attribute values. For instance, for goat farms with different levels of emissions you make a map displaying smaller and bigger circles around these farms in accordance with their emission levels.
Click on Vector in the Toolbar menu
In the drop-down menu, choose Geoprocessing Tools
Click on Variable Distance Buffer
At Input Layer, choose the layer with objects around which you wish to create a buffer (goat farms)
At Distance Field, choose the attribute whose value differences need to be expressed in the buffer (emissions)
Choose the number of Segments (this will determine how accurate the buffer boundaries are)
Select a temporary layer or choose a new name
Click on Run
You can use Union to place two layers on top of each other and create a new layer which contains all objects from both original layers, and new objects have been created for intersecting areas (in the case of two vector files). In the Attribute Table you will find the data from both layers for each object.
Click on Vector in the Toolbar menu
In the drop-down menu, choose Geoprocessing Tools
Click on Union
Choose an Input Layer and an Input Layer 2 (the data of this latter layer will be included at the bottom of the Attribute Table)
Select a temporary layer or choose a new name
Click on Run
The Dissolve option allows you to merge all objects from a certain layer into one object. In this case, the Attribute Table will have only one row. If relevant, you can choose an attribute to merge different object categories. For instance, you can create a layer of neighbourhoods in Breda with the same urbanization rate. The Attribute Table will then have just as many rows as there are categories (each category will become a separate object).
Click on Vector in the Toolbar menu
In the drop-down menu, choose Geoprocessing Tools
Click on Dissolve
Select the layer whose objects you want to merge together
If applicable, disable Dissolve All, and choose an attribute that determines the objects in the new layer
Select a temporary layer or choose a new name
Click on Run
By means of Difference you can place two layers on top of each other. You create a new layer which contains all the objects from the Input Layer that don’t intersect or overlap with the difference layer. Objects that are situated outside the boundary of the difference layer will be split up and only the part falling outside the difference layer will be included in the new map layer. The Attribute Table will not change.
Click on Vector in the Toolbar menu
In the drop-down menu, choose Geoprocessing Tools
Click on Difference to open the window
At Input Layer, fill in the layer whose objects you wish to include in the new layer
At Difference Layer, fill in the layer with which you want to make your overlap
Give the new layer a name or opt for a temporary layer
Click on OK
With Clip you can make a spatial cut-out of the data of a particular area. Clip works as a cookie cutter. The clip layer is a layer with a polygon, for instance a municipal boundary – this is the cookie cutter. The Input Layer is the layer which you want to retrieve your data from, for instance, all roads in Brabant – this is the dough. The Clip option will result in a map layer containing only the roads in the municipality concerned.
Click on Vector in the Toolbar menu
In the drop-down menu, choose Geoprocessing Tools
Click on Clip
At Input Layer, choose the layer which you want to retrieve data from (the dough)
At Clip Layer, choose the layer with the polygon of which you want to have the data (the cookie cutter)
Give the new layer a name or opt for a temporary layer
Click on Run