The Vector Processing plugin contains several processing algorithms applied to vector data:

"PostGIS doens't recognize this projection. Please, reproject your data to a correct one. Or save your result as Vector File, and afterwards use Exchange to put the result in PGIS, changing the USER SRID to a valid one."

- Buffer - The Buffer is a spatial operation that can be applied to a single layer. The buffer zone may be defined as an area generated around an object with a predetermined distance.

- Difference - The Difference is spatial operation and needs two layers. This operation creates a new layer composed of the difference between geometries of two layers.

- Dissolve - The Dissolve operation is applied to a single layer and a chosen group of attributes that can be summarized. The idea is to generate a new layer with summarized information. The geometries of each group are dissolved through the UNION spatial operation and the attributes can be summarized using of the dissolve operation: sum, count, maximum, minimum, average and so on.

- Geometric Operations - The Geometric Operations available are Centroid, Convex Hull and Minimum Bounding Rectangle (MBR). These operations return a new geometry as a result. In addition there is also basic operations such as Perimeter, Area and Lenght, returning only a numeric value for each geometry.

- Identity - The Identity is spatial operation and is needs two layers. This operation creates a new layer composed of the difference and the intersection between geometries of the two layers.

- Intersection - The Intersection is spatial operation and needs two layers. The first one containg polygons that form a clipping mask, and the second one (with any kind of representation ex. polygons, lines, points) that will be clipped. The result is a new layer formed by the objects of the second layer in the intersection with the clipping mask.

- Line to Polygon - The Line to Polygon operation is applied to a single layer composed of lines. This operation creates a new layer where all closed lines are transformed in polygons.

- Merge - The Merge is spatial operation and needs two layers. This operation makes the insertion of a layer data in another layer

- Polygon to Line - The Polygon to Line operation is applied to a single layer composed of polygons. This operation creates a new layer where all polygons are trasnformed in closed lines.

- Multipart to Singlepart - The Multipart to Singlepart operation split multipart geometries to singlepart geometry.

- Union - The Union is a spatial operation and needs two layers. This operation makes an union between two layer considering the intersection.

- Check Geometry Validity - It is used to identify/visualize invalid geometries, and fix them.

"PostGIS doens't recognize this projection. Please, reproject your data to a correct one. Or save your result as Vector File, and afterwards use Exchange to put the result in PGIS, changing the USER SRID to a valid one."