1. A method for displaying selected portions of a three-dimensional (3D) volumetric data set representing a subsurface formation, comprising: generating at least one two-dimensional (2D) canvas, the 2D canvas corresponding to a plane in the 3D data set, the 2D canvas being shown in a first display window; creating one or more 2D primitives on the 2D canvas; creating a 3D volume from the one or more 2D primitives created on the 2D canvas; forming a volumetric region, which is a subset of the 3D volumetric data set, from an intersection between the 3D volume created from the one or more 2D primitives and the 3D volumetric data set; and displaying the volumetric region in a 3D scene, the 3D scene being shown in a second display window.