Groups geometries to be treated as one. The node takes the set of geometries connected to the input ports and outputs one geometry which is the union of the inputs. This union of geometries can then be used for geometry queries (raycast, closest location, emission, etc.) as if they were one.
This node does not calculate the Boolean union of the geometries but simply groups the geometries to be treated as one in the graph.
The geometries do not need to be of the same type. One can group curves, with polygon meshes and point clouds, for example.
This node outputs the same result as a Get Data node on a group of objects.
