Is it possible to perform automatic snapping of polygons in QGIS or ArcGIS?

Note: in the picture below white space between the polygons is blank space – it does not contain any polygons as a result of Intersect or Union functions.

Answer

In ArcGIS, you should be able to use the Integrate tool to snap these features together (I am pretty sure it will work on a single feature class).

You should BE SURE TO MAKE A COPY OF YOUR DATA before running this tool, though, as the Integrate tool modifies the input data directly (you are not writing to a new output). You could however get around this limitation by creating a model that:

1. creates a new output layer using the the Copy Features tool, and then


2. run the Integrate tool on the output of Copy Features.

There are a number of caveats to this tool, and you should be sure to READ ALL OF THE HELP before performing this action on your data.